Sickle-cell anaemia

36 min read

What is sickle cell anaemia?

Sickle cell anaemia is a genetic (inherited) blood disorder in which red blood cells, which carry oxygen around the body, develop abnormally.

Rather than being round and flexible, the sickle red blood cells become shaped like a crescent (or sickle).

These abnormal red blood cells can then clog sections of blood vessels leading to episodes of pain which can be severe. These episodes are called a sickle cell crisis (also known as a vaso-occlusive crisis).

They can last from a few minutes to several months, though on average most last five to seven days.

The abnormal blood cells have a shorter life-span and are not replaced as quickly as normal; this leads to a shortage of red blood cells, called

. Symptoms of anaemia include tiredness and breathlessness; especially after exercise.

Read more about the

symptoms of sickle cell anaemia


Symptoms of sickle cell anaemia can have a significant impact on quality of life. Potential complications can be life-threatening.

They include:

  • stroke
    – where the supply of blood to the brain becomes blocked
  • acute chest syndrome – where the lungs suddenly lose their ability to breathe in oxygen; often as a result of infection
  • increased vulnerability to infection
  • pulmonary hypertension
    – where the blood pressure inside the blood vessels that run from the heart to the lungs becomes dangerously high

However, following improvements in preventative treatment, many complications associated with sickle cell anaemia can be avoided and most people with the condition live much longer than previously.

Read more about the

complications of sickle cell anaemia

When to seek urgent medical advice

Due to the risk of life-threatening conditions, it is important to look out for any signs or symptoms that the patient's health has suddenly deteriorated.

These include:

  • high temperature (fever) of 38C (100.4F) or above
  • severe pain that develops during a sickle cell crisis that cannot be controlled using over-the-counter painkillers, such as paracetamol or ibuprofen
  • breathing difficulties

Read more about

when to seek urgent medical advice

Treating sickle cell anaemia

Treatment helps reduce the severity and frequency of the symptoms of sickle cell anaemia and prevent complications.

In some cases a person with sickle cell anaemia may require regular blood transfusions to help reduce the risks of complications.

Read more about the

treatment of sickle cell anaemia

Causes of sickle cell anaemia

Sickle cell anaemia is caused by a genetic mutation that affects normal development of red blood cells.

A genetic mutation is when the instructions found inside all living cells become scrambled in some way meaning one or more of the processes of the body do not work in the way they should.

The mutation that causes sickle cell anaemia is often referred to as the sickle cell trait.

Having the sickle cell trait itself will not cause a person to develop sickle cell anaemia. But if two people with the trait conceive a child then there is a one in four chance that child will be born with sickle cell anaemia.

Read more about the

causes of sickle cell anaemia


Sickle cell anaemia can be diagnosed with a blood test.

Anyone from at risk groups having a general anaesthetic should be tested for the sickle cell trait or thalassaemia because a general anaesthetic temporarily lowers the amount of oxygen in the blood, which could be dangerous for someone with the condition.

Read more about

screening for sickle cell anaemia

Blood Blood supplies oxygen to the body and removes carbon dioxide. It is pumped around the body by the heart. Blood vessels Blood vessels are the tubes in which blood travels to and from parts of the body. The three main types of blood vessels are veins, arteries and capillaries. Bone marrow Bone marrow is the soft, spongy tissue in the centre of bones that produces blood cells. Disease A disease is an illness or condition that interferes with normal body functions. Genetic Genetic is a term that refers to genes, the characteristics inherited from a family member. Lungs Lungs are a pair of organs in the chest that control breathing. They remove carbon dioxide from the blood and replace it with oxygen. Oxygen Oxygen is an odourless, colourless gas that makes up about 20% of the air we breathe. Pain Pain is an unpleasant physical or emotional feeling that your body produces as a warning sign that it has been damaged. Tissue Body tissue is made up of groups of cells that perform a specific job, such as protecting the body against infection, producing movement or storing fat.


Sickle cell anaemia can cause a wide range of symptoms though not everyone with the condition will experience all the symptoms.

Sickle cell crisis (episodes of pain)

Episodes of pain during a sickle cell crisis are one of the most common and upsetting symptoms of the condition.

A sickle cell crisis (also known as a vaso-occlusive episode or VOE) is triggered when the abnormal blood cells block the small blood vessels that supply the body’s tissues.

This causes the cells in the affected tissue to be damaged, resulting in swelling (inflammation) which irritates nearby nerve endings.

During a sickle cell crisis, younger children may develop painful swelling in their hands or feet. This is often the first noticeable symptom.

As a child grows older, pain can affect any area of the body, although the most common areas are:

  • ribs
  • spine
  • pelvis
  • abdomen
  • sternum (breastbone)
  • long bones in the legs and arms

People with sickle cell anaemia describe the pain as aching, throbbing, sharp and shooting, penetrating, or burning.

Symptoms can be severe and episodes can last from a few minutes to several weeks with an average duration of around five to seven days.

Children may experience from one or two episodes to 14 episodes a year .

A sickle cell crisis can often occur for no apparent reason, though there are certain triggers, such as:

  • sudden changes in body temperature; either the result of an infection causing a high temperature or a change in the outside environment
  • dehydration
    (a lack of water in the body)
  • the body suddenly becoming short of oxygen as a result of exercise, sudden exertion or stress

In older children and adults with sickle cell anaemia, potential triggers include:

  • alcohol
  • cigarettes
  • illegal drugs such as cocaine and cannabis

It is important to try and learn what triggers set off an episode so they can be avoided.


Anaemia ( lack of red blood cells) is a common symptom of sickle cell anaemia. The abnormal cells have a shorter life-span and are not replaced quickly enough.

Symptoms include:

  • fatigue - (feeling tired all the time and having a general lack of energy)
  • dyspnoea (shortness of breath)
  • palpitations (irregular heartbeat)

Your child’s body is usually able to compensate for the lack of red blood cells by an increase in heartbeat, although symptoms of fatigue may persist.

This can make participating in physical activities, such as sports, more difficult.

Aplastic crisis

A more serious type of anaemia, known as aplastic crisis, can occur if your child develops a type of common childhood infection called

slapped cheek syndrome
(also known as parvovirus B19).

The combination of infection and pre-existing anaemia can lead to a sharp and sudden drop in the number of red blood cells inside your child’s body.

Symptoms of an aplastic crisis include:

  • very pale skin
  • fatigue
  • headache
  • fever (high temperature) of 38C (100.4F) or above
  • tachycardia (rapid heartbeat)
  • dizziness
  • fainting

Vulnerability to infection

Children with sickle cell anaemia are more vulnerable to infection, particularly if under three years of age. This is because the abnormal blood cells can disrupt the normal functions of the spleen.

The spleen is an organ located in the abdomen (the lower left side of the body, behind the stomach). It plays an important role in filtering harmful bacteria and viruses from the blood.

Children with sickle cell anaemia are particularly vulnerable to three types of infection:

As younger children with sickle cell anaemia have an increased risk of developing an infection, it is often recommended that they take daily doses of antibiotics as a precaution.

Additional vaccinations such as the Pneumovax (which protects against some types of bacteria that can cause pneumonia) and the meningococcal vaccines (which protect against meningitis and septicaemia), as well as annual flu vaccinations, may be recommended.

Jaundice and gallstones

Jaundice (yellowing of the skin and the whites of the eyes) is a common symptom of sickle cell anaemia. Jaundice occurs because the rapid breakdown of abnormal red blood cells leads to a build-up of a waste product in the body called bilirubin.

The build-up of bilirubin often leads to the formation of small crystals called

. Most gallstones do not cause symptoms but occasionally they can block the bile duct which drains bile from the liver into the bowel. This can trigger jaundice.

More commonly, the stone can get stuck in the gallbladder, causing it to become swollen leading to abdominal pain and nausea.

Avascular necrosis

Avascular necrosis (AVN) is the medical term used to describe the loss of bone tissue due to a restriction of blood supply.

In children with sickle cell anaemia, AVN usually affects the hip. The first sign of this can be a limp or pain in the groin. AVN can lead to persistent hip pain that can last for several months. In serious cases, your child may be advised to avoid putting any weight on the affected leg, and may need to use crutches or a wheelchair.

Less commonly, AVN can affect the shoulder joint or elbow.

Leg ulcer


leg ulcer
is a painful, open sore that develops on the lower leg, usually close to the ankle. Leg ulcers often develop after a skin infection or injury, such as a cut or puncture wound.

Children with sickle cell anaemia have an increased risk of developing leg ulcers. This is because the lack of normal red blood cells means their leg does not receive the nutrients it needs to keep skin and surrounding tissue healthy.

Delayed growth

Red blood cells provide the oxygen required for physical development. In sickle cell anaemia, it is likely that your child will experience delayed growth compared with other children.

Many children with sickle cell anaemia will also experience

at a later stage (around 13-14 years of age for girls and 13½-14½ years of age for boys).

The average age of puberty in children who are unaffected by sickle cell anaemia is 11 years of age for girls and 12 years of age for boys.


is the medical term that describes a persistent and painful erection of the penis. Episodes of priapism can sometimes last for several hours.

Priapism can affect teenage boys and men who have sickle cell anaemia because the abnormal blood cells can cause blood to become trapped in the penis.

Priapism does not usually develop as a result of sexual stimulation, and it can often occur for no apparent reason, usually during a sickle cell crisis.

Teenage boys may be reluctant to mention that they are experiencing priapism due to feelings of embarrassment.

If you have a teenage son with sickle cell anaemia, it is very important you emphasise the importance of seeking immediate treatment for priapism.

This is because episodes of priapism that last more than two hours can cause permanent damage to the penis, and may affect the ability to obtain an erection in the future.

When to seek urgent medical advice

Due to the risk of life-threatening conditions, it is important to look out for any signs or symptoms that your child’s health has suddenly worsened.

Signs and symptoms to look out for are:

  • fever (high temperature) of 38C (100.4F) or above
  • severe pain that develops during a sickle cell crisis that cannot be controlled using over-the-counter painkillers, such as paracetamol or ibuprofen
  • breathing difficulties
  • severe abdominal pain or swelling of the abdomen
  • severe headache, stiff neck or dizziness
  • changes in mental state, such as appearing confused or drowsy
  • episodes of priapism (see above) that last longer than two hours
  • seizures (fits)

If your child develops any of the above symptoms, immediately phone your doctor for advice. If this is not possible, take your child to your local accident and emergency (A&E) department.

You can take them by car if they are well enough to travel. However, if this is not the case, dial for an ambulance.

It is very important when requesting an ambulance or visiting A&E that you inform all ambulance, medical and nursing staff that your child has sickle cell anaemia. This is so that they are aware of the potentially serious nature of your child’s condition.


Sickle cell anaemia is caused by a genetic mutation that affects the normal development of haemoglobin.

A genetic mutation is a permanent change in the normal pattern of genetic information inside all living cells. This results in one or more of the processes of the body not working as they should.


Haemoglobin is a substance found in red blood cells which acts as a sort of transport mechanism for your blood.

As blood passes through your lungs, the haemoglobin pulls in oxygen while at the same time releasing carbon dioxide. This process is known as oxygenation.

After moving away from your lungs, the haemoglobin delivers oxygen to the body’s tissue and removes excess carbon dioxide to take back to your lungs. This process is called deoxygenation.

During deoxygenation, healthy haemoglobin molecules should smoothly rearrange themselves into a different shape. In cases of sickle cell anaemia, the smooth rearrangement does not occur due to the mutated gene.

Instead, the haemoglobin inside blood cells clumps together into solid structures. The clumping distorts the normal shape of the red blood cells, causing them to take on a characteristic rigid, sickle shape.

The genetics of sickle cell anaemia

Genes come in pairs. You receive one copy of a gene from your mother and one copy from your father.

To develop sickle cell anaemia you would need a pair of the mutated genes; one from your mother and one from your father.

If you only receive one copy, you will not develop sickle cell anaemia, but you will be a carrier of the sickle cell gene. This is often referred to as having the sickle cell trait. It is estimated that 1 in 10 people of African or Caribbean descent has this trait.

If you are a carrier, you will not usually notice any obvious symptoms unless you are in an low oxygen environment, such as on top of a mountain.

If both you and your partner have the sickle cell trait, there is a risk that any children you conceive will inherit a pair of mutated genes and develop sickle cell anaemia. The chances of sickle cell anaemia being passed on are outlined below:

  • There is a one in four chance your baby will receive a pair of normal haemoglobin genes.
  • There is a one in two chance that your baby will receive one normal gene and one mutated gene. In this case, they will not have sickle cell anaemia, but they will carry the sickle cell trait.
  • There is a one in four chance that your baby will receive a pair of mutated genes. This means that they will have sickle cell anaemia.

If one parent has the sickle cell trait and the other parent has normal haemoglobin, the baby will not develop sickle cell anaemia. However, there is a one in two chance that the baby will receive the sickle cell trait.

Finally if you have ‘full-blown’ sickle cell anaemia and your partner has the sickle cell trait, any baby you have has a one in two chance of developing sickle cell anaemia.

This is because it is certain that they will receive a mutated gene from you and there is a one in two chance that they will receive a mutated gene from your partner.

Read more about



Sickle cell anaemia can be diagnosed with a blood test. The blood is checked for defective haemoglobin.

A small level of defective haemoglobin would suggest the sickle cell trait, but not sickle cell anaemia. A high level indicates sickle cell anaemia.

Antenatal screening

The purpose of antenatal screening (screening carried out during pregnancy) is to check for inherited disorders, such as sickle cell anaemia, and to provide parents with the information they need to make informed decisions.

Antenatal screening for the sickle cell trait is available where the condition is most common, typically areas with large Afro-Caribbean communities. In parts of the country where sickle cell anaemia is uncommon, a questionnaire that focuses on family origin is used as an initial screening device to assess the risk of sickle cell disorders.

Pregnant women are routinely screened for the sickle cell trait. If they test positive their partner will also be offered the test. If both parents have the trait, there is a one in four chance that their baby will have sickle cell anaemia.

Further testing is available (if you want it) to confirm whether your baby will definitely be born with sickle cell anaemia. One method is to take a sample of cells from the placenta (the organ that is attached to the womb lining during pregnancy). This test is commonly known as

chorionic villus sampling


Being told your baby will be born with sickle cell anaemia can be upsetting so you will be offered counselling to allow you and your partner the opportunity to express your feelings, and question how the diagnosis may affect you.

The counsellor will make you aware of the different options available, allowing you to make a more informed decision about how to proceed with the pregnancy.

Pre-implantation Genetic Diagnosis

Pre-implantation Genetic Diagnosis (PIGD) is an option for couples who know they are both carriers of the sickle cell trait but who do not want to give birth to a child with sickle cell anaemia.

PIGD is similar to in vitro fertilisation (IVF). IVF is a method of helping infertile couples to conceive by surgically removing an egg from the woman's ovaries and fertilising it with the man’s sperm in a laboratory.

As with IVF, PIGD involves removing eggs from a woman’s ovaries. These are fertilised using sperm taken from her partner. The fertilised embryo can be tested for sickle cell anaemia. If test results are negative, the embryo can then be implanted into the woman’s womb.

As with other types of IVF there is no guarantee that a course of PIGD will lead to a successful pregnancy. Overall, the chance of a couple having a baby born following treatment with PIGD is around one in five.

PIGD is a new procedure only available at a number of specialist sickle cell centres.

In most cases you would need to pay for PIGD on a private basis and unfortunately the treatment is expensive at around £8,000 for a course of treatment.


If your child is diagnosed with sickle cell anaemia, they will be referred to a care team in a specialist sickle cell center.

Sickle cell centres are specialist units, usually based in large hospitals, which have a high level of experience and expertise in treating people with sickle cell anaemia.

A detailed plan outlining future medical care will be drawn up and you will be given information and support to help you manage your child’s condition.

Your care team

Sickle cell anaemia is a complex disorder that requires a number of different healthcare professionals working together as a team. Members of your care team may include:

  • a paediatrician (a doctor who specialises in the treatment of children)
  • a haematologist (a doctor who specialises in the treatment of blood disorders)
  • a clinical psychologist
  • a pharmacist
  • a physiotherapist
  • a social worker
  • a specialist nurse – who will usually act as the first point of contact between yourself and the rest of the team

Your child’s care plan

The objectives of the care plan are to:

  • try to prevent sickle cell crises occurring
  • provide adequate pain relief when a crisis does occur
  • reduce the risk of serious complications occurring, such as infections and stroke
  • treat other associated symptoms of sickle cell anaemia, such as anaemia](/health-library/conditions/vitamin-b12-and-folate-deficiency/#introduction) (lack of red blood cells) or [priapism (persistent and painful erection)

Preventing a sickle cell crisis

Following lifestyle advice, such as drinking plenty of fluids, can help reduce the risk of experiencing a sickle cell crisis. Read more

self-care advice for people with sickle cell anaemia

Some children (and adults) will continue to experience episodes of pain despite their best preventative efforts. In such circumstances, a medication called hydroxycarbamide may be recommended.


Hydroxycarbamide is usually recommended if a child or adult has recurring episodes of a sickle cell crisis. This is usually more than six episodes within the past 12 months.

Hydroxycarbamide may also be recommended if:

  • testing shows that a person has an increased risk of a stroke (see below)
  • a person has severe symptoms of anaemia that are not responding to other treatments

Hydroxycarbamide was originally designed as a type of chemotherapy medication to treat cancer, but researchers found that it stimulated the production of a type of haemoglobin called foetal haemoglobin.

Foetal haemoglobin is a type of haemoglobin found in unborn babies. It is gradually replaced by adult haemoglobin as the child gets older.

As foetal haemoglobin is not affected by the sickle cell mutation, it is able to take over the role of adult haemoglobin to some extent. This helps reduce the risk of someone with the condition experiencing a sickle cell crisis.

Hydroxycarbamide has also proved effective in preventing acute chest syndrome (read more about the

complications of sickle cell anaemia
). So the medication may also be recommended if a person has had two or more episodes of acute chest syndrome.

Hydroxycarbamide is available in capsule form and people with sickle cell anaemia are usually required to take one tablet every day.

A short-term side effect of hydroxycarbamide is that it can lower the amount of other blood cells, such as:

  • White blood cells: these cells help fight infection, so having a low number of them can make a person more vulnerable to infection
  • Platelets: these cells help the blood to thicken and form clots, so having a low number of them makes a person bleed and bruise more easily

So it is usually recommended that a person taking hydroxycarbamide has regular blood tests to monitor the their blood cells. If the blood cells drop below a certain level, the dosage may need to be adjusted.

Other side effects can include:

As a precaution, the use of hydroxycarbamide is not recommended during pregnancy. This is because high doses of hydroxycarbamide may increase the risks of the baby being born with birth defects.

There is no evidence that much lower doses pose a similar risk. But as a precaution, sexually active men and women are advised to use a reliable method of contraception while taking hydroxycarbamide.

The use of hydroxycarbamide has also been linked to an increased risk of developing leukaemia (cancer of the white blood cells) in later life. Although this risk is thought to be very small.

In most cases the potential benefits hydroxycarbamide outweigh the risks, though you should discuss any concerns that you may have with your child’s (or you own) care team.

Pain management

Although sickle cell crises can be distressing, most episodes can be managed at home.

Over-the-counter painkillers, such as

, can be used to control symptoms of mild pain. Always follow the dosage instructions and ensure that the recommended amount is not exceeded.

If your child’s pain is more troublesome, your doctor may prescribe stronger painkillers, which usually contain a combination of paracetamol and codeine.

Other ways to ease your child’s pain are described below.

  • Ensure that your child has plenty to drink. Fluids help thin the blood and clear out the sickle cells that are clogging the blood vessels.
  • Place your child in a warm bath. Ensure that the water is not too hot and do not let it get too cold because changes in temperature could trigger another crisis.
  • Use a warm towel or a heated pad to gently massage the affected body part. Many pharmacists sell electrical pads that can be used for this purpose.
  • Use suitable distractions. For example, reading them a story, watching a film or playing their favourite computer game will help to take their mind off the pain.

If your child’s pain is severe, take them to your local accident and emergency (A&E) department. If they are too unwell to travel by car, call for an ambulance.

Severe pain can be treated by giving your child injections of a strong opiate-based painkiller, such as morphine.

Some parents are concerned that regular use of opiate-based painkillers will cause their child to become addicted. Your specialist or staff at the treatment clinic will carefully regulate the dosage to minimise the chances of addiction.

People with sickle cell anaemia are no more likely to become addicted to opiates than anyone else.

Reducing the risk of infection

Due to the increased risk of developing serious infections, such as meningitis, it is recommended that your child takes daily doses of antibiotics, usually penicillin. In children who are allergic to penicillin, an alternative antibiotic, such as erythromycin, can be used.

Ideally, your child should take penicillin for the rest of their life or, at the very least, until they reach adulthood. The long-term use of penicillin does not pose any risks to your child’s health.

It is very important that your child’s vaccinations are up to date. As well as the routine childhood vaccinations, such as meningitis C and tetanus, your child will probably require some additional vaccinations due to their increased risk of infection.

These may include:

  • annual influenza (flu) vaccinations
  • hepatitis B vaccine

As children with sickle cell anaemia often require blood transfusions, there is a small risk that they could develop blood-borne viruses, such as hepatitis B. The hepatitis B vaccination will prevent this.

Reducing the risk of a stroke


is one of the most serious complications of sickle cell anaemia. Reducing the risk of a stroke will be an important part of your child’s treatment.

Your child’s risk of a stroke can be assessed using a test known as a Transcranial Doppler (TCD) scan. A TCD scan uses ultrasound to measure the flow of blood through the brain. A faster blood flow could be the result of narrowed blood vessels due to clogging from abnormal red blood cells. This is a major risk factor for having a stroke.

If your child is diagnosed with sickle cell anaemia, it is recommended that they have an annual TCD scan from the age of three.

The results of the scan will show whether your child has a high, moderate, or low risk of having a stroke. If the results show a high or moderate risk, a further TCD scan will be carried out within two months.

If the results still indicate high stroke risk, regular blood transfusions to improve blood supply to the brain will usually be recommended.

Chelation therapy

Regular blood transfusions can help reduce your child’s risk of suffering a stroke by 90%, but also leave excess iron in the body.

This can cause a number of potentially dangerous complications, including liver damage, delayed physical and sexual development and

heart disease

This means people who receive regular blood transfusions must also be treated to remove excess iron from their body. This treatment is known as chelation therapy.

Deferasirox is a medication increasingly used during chelation therapy. It works by locking onto or binding the iron molecules in the body, before releasing them through urine or stools. Deferasirox is available in tablet form and most people need to take one tablet a day.

Your child will require regular blood and urine tests to measure the amount of iron in their body so that the effectiveness of their chelation therapy can be assessed.

Treating associated symptoms


In most cases, making sure your child eats a healthy diet should provide enough nutrients to compensate for their lack of healthy red blood cells.

Dietary supplements, such as folic acid (which helps stimulate the production of red blood cells) are usually only required if your child has a restricted diet, such as a vegetarian or vegan diet.

Never give your child iron supplements without first consulting your doctor.

The type of anaemia associated with sickle cell is not due to an iron deficiency and increasing your child’s levels of iron could be potentially dangerous, particularly if they have been receiving blood transfusions.

Read more about the

treating anaemia

A sudden worsening of your child’s anaemia, such as an aplastic crisis may require a blood transfusion to increase the amount of red blood cells to a healthy level.


If your child has pain due to gallstones, it is usually recommended they have their gallbladder surgically removed. This type of operation is known as a


Avascular necrosis

Mild cases of avascular necrosis can be treated with painkillers to relieve pain and a type of medication called bisphosphonates to prevent further loss of bone tissue.

More severe cases may require referral to an orthopaedic surgeon (a surgeon who specialises in treating bones and joints), as surgery may be required to repair bone damage.

Leg ulcer

A leg ulcer can be treated by cleaning the ulcer with sterile (germ-free) water and dressing with a bandage. Read more about the

treatment of leg ulcers

Delayed growth

Most children with sickle cell anaemia should ‘catch up’ on growth and reach a normal height by early adulthood.

In more severe cases, zinc supplements may be recommended. Zinc is a metal that plays an important role in stimulating bone and muscle growth.

If your child does not show any physical signs of puberty by the time they have reached 14 or 15 years of age, a referral to an endocrinologist (a doctor who specialises in treating hormonal conditions) is recommended. A short course of hormonal medication may be prescribed to help trigger puberty.

Read more about the

treatment of delayed puberty


If your child develops priapism (a persistent and painful erection of the penis), these self-care techniques may relieve symptoms:

  • Make sure your child drinks plenty of fluids.
  • Encourage your child to urinate regularly.
  • Use over-the-counter painkillers to help relieve pain.
  • A warm shower or bath can help encourage blood circulation.

If an episode of priapism lasts more than two hours, take your child to the nearest accident and emergency (A&E) department.

Treatment includes medication to stimulate blood circulation or using a needle to drain blood from the penis.

Read more about treating priapism.


Reducing the risk of a sickle cell crisis

There are a number of things your child can do to reduce their risk of having a sickle cell crisis. These are described below.

Drink plenty of water

It is particularly important to drink plenty in hot weather because dehydration increases the likelihood of sickle cells forming.

Your child’s sickle care team can give you detailed advice about your child’s recommended fluid intake.

Exercise regularly

Your child should take regular exercise, but should avoid becoming too tired or seriously out of breath.

Children with sickle cell anaemia usually have less stamina than their classmates. So activities that allow them to take frequent breaks such as sprinting or cycling are probably a better choice than long-distance running or rugby.

Your doctor can advise further and recommend an appropriate level of exercise for your child.

Eat a healthy, balanced diet

Eating a healthy diet encourages your child’s growth and development, and strengthens their immune system, which helps reduce their risk of developing infections.

A low-fat, high-fibre diet is recommended, including plenty of fresh fruit and vegetables (five portions a day) and whole grains. Read more about healthy eating.

The same advice applies to adults with sickle cell anaemia who, in addition, should:

  • limit the amount of alcohol they drink: recommended daily limits are 3-4 units for men and 2-3 units for women (a unit of alcohol is equal to about half a pint of normal strength lager, a 25ml measure of spirits or a small glass of wine)
  • avoid smoking
  • avoid misusing illegal drugs such as cannabis and cocaine; these have been known to trigger a sickle cell crisis

Avoiding triggers

You should also try to avoid known triggers, such as:

  • extreme temperatures: exposure to extreme heat or cold can trigger the formation of sickle cells
  • high altitude areas: lack of oxygen at high altitudes may trigger a crisis
  • stress: stressful events have been shown to trigger a crisis

Learning relaxation techniques, talking problems over with family and friends, or joining a support group have all been shown to reduce stress in people living with sickle cell anaemia.

Read more about ways of dealing with stress.

Taking control

There is evidence that a type of talking therapy known as

cognitive behavioural therapy (CBT)
can be useful for people with long-term conditions such as sickle cell anaemia.

CBT helps you to cope with sickle cell anaemia by changing how you think about your condition, such as seeing it as a manageable problem, rather than a force over which you have no control.

Studies have shown that people with sickle cell who had CBT later reported lower levels of pain and an improvement in their quality of life.

Finding out as much as possible about sickle cell anaemia may also help you feel more in control of your condition.

The Sickle Cell Society’s website is a good place to start.


As sickle cell anaemia can block the flow of oxygen to parts of your child’s body, it can cause serious complications. These are described below.



is one of the most serious complications of sickle cell anaemia. It can happen when the sickle cells block the flow of oxygen to your child’s brain.

The main stroke symptoms can be remembered with the word FAST: Face-Arms-Speech-Time.

  • Face: may have dropped on one side, the person may not be able to smile or their mouth or eye may have drooped
  • Arms: the person with a suspected stroke may not be able to lift one or both arms and keep them there because of arm weakness or numbness
  • Speech: may be slurred or garbled, or the person may not be able to talk at all despite appearing awake
  • Time: dial for an ambulance immediately if you see any of these signs or symptoms

Some children with sickle cell anaemia may experience a transient ischaemic attack (TIA), or ‘mini-stroke’. A TIA occurs when the supply of blood to the brain is temporarily interrupted.

Symptoms of a TIA are similar to those of a stroke, and last from a few minutes to a few hours before disappearing completely. However, do not ignore a TIA because it is a serious warning there is a problem with the brain’s blood supply.

If your child has a TIA, contact your doctor, local hospital or out-of-hours service immediately to arrange a specialist assessment.

Strokes can be treated by blood transfusions. Blood transfusions are not effective for treating strokes in people who do not have sickle cell anaemia because the causes are usually different, such as a blood clot or burst artery.

Once your child’s condition has stabilised, it is usually recommended that they continue receiving regular blood transfusions to reduce the risk of further strokes.

Acute chest syndrome

Acute chest syndrome is a life-threatening lung condition. The exact cause is unknown, though it is thought that an infection in the lungs, which are already damaged by sickle cell anaemia, can cause problems with air circulating there.

The symptoms of acute chest syndrome include:

  • high temperature (fever) of 38C (100.4F) or above
  • chest pain
  • cough
  • breathing difficulties
  • more rapid breathing than normal

If you think your child has developed acute chest syndrome, call for an ambulance.

Acute chest syndrome requires emergency medical treatment with antibiotics, blood transfusions, oxygen and intravenous fluids (where liquids are pumped directly into your child’s veins to help rehydrate their body).

Splenic sequestration crisis

Splenic sequestration crisis (SCC) is a complication that can affect sickle cell anaemia patients between the age of six months and three years.

SSC occurs when the sickled red blood cells become trapped inside the spleen. This causes the spleen to swell and at the same time leads to a dangerous drop in the number of red blood cells in the rest of the body.

Symptoms of SSC include:

  • unusually pale skin
  • feeling very tired
  • shortness of breath
  • irritability
  • tachycardia (rapid heartbeat)
  • abdominal pain, usually in the left side of your child’s abdomen
  • swelling of the spleen (you should be able to check for this by gently touching the upper left side of your child’s abdomen, just underneath their rib cage)

If you think your child has experienced SCC, immediately contact your doctor or a member of their sickle cell care team for advice. If this is not possible, call your local out-of-hours service.

Some episodes of SSC are minor and resolve themselves without the need for treatment. However, more severe episodes will require a blood transfusion in hospital.

Vision problems

In cases of sickle cell anaemia, blood vessels that lead to the eyes can get blocked by sickled cells causing damage to the retina, known as retinopathy. The retina is a light-sensitive layer of cells that processes light coming into the eye and sends signals to the brain.

Symptoms of retinopathy can include:

  • floaters
    (coloured spots that ‘float’ in your field of vision)
  • blurred vision
  • vision blocked by patches or streaks
  • reduced night vision
  • most seriously, sudden vision loss

If your child complains of any deterioration in their vision, contact your sickle cell care team for advice.

Retinopathy can be treated using laser surgery to repair damage to the blood vessels and retina. Your child should have eye examinations at least once a year.

Pulmonary hypertension

Pulmonary hypertension is high blood pressure in the blood vessels that carry blood from the heart to the lungs. This is a common complication in teenagers and adults with sickle cell anaemia affecting over half of them.

It is a serious medical condition as it results in damage to the right-hand side of the heart making the heart less efficient at pumping blood around the body and getting oxygen to the muscles. This leads to symptoms such as:

  • shortness of breath
  • fatigue (tiredness)
  • feeling faint or dizzy

If it is not treated, pulmonary hypertension can cause

heart failure
, which is when the heart struggles to pump enough blood around the body. This can be fatal.

Because of this risk your care team may recommend regular tests to check the blood pressure inside these vessels. This can be done using a machine called an echocardiogram.

An echocardiogram is a type of ultrasound scan that can be used to see how well your heart is working. An ultrasound is a procedure that uses high-frequency sound waves to create an image of part of the inside of your body, such as your heart. This can be used to estimate the pressure in your pulmonary arteries.

Treatment options for people with sickle cell anaemia who develop pulmonary hypertension include hydroxycarbamide and regular blood transfusions. These treatments are not used in people with pulmonary hypertension who do not have sickle cell anaemia.

In some case additional medications such as iloprost and sildenafil, designed to widen blood vessels and reduce pressure, can be tried.

Read more about the

treatment of pulmonary hypertension

Kidney problems

The kidneys are designed to filter waste products out of the blood. But due to the ‘stickiness’ of blood in people with sickle cell anaemia the kidneys can become damaged over time.

This can lead to a number of problems, such as:

  • having blood in your urine
  • bedwetting
  • high blood pressure
    – the kidneys play a role in regulating blood pressure

In the past, around one in three adults with sickle cell anaemia experienced

end stage kidney disease
(also known as kidney failure) which is where the kidneys lose most or all of their functioning abilities. Recent advancements in treatment should improve these figures.

Treatment options for kidney failure include:


Living with a condition as unpredictable as sickle cell anaemia can cause anxiety and stress, often triggering depression.

Research has found around half of people living with sickle cell anaemia will experience depression at least once during their life.

It can be difficult to spot depression in children, particularly in teenagers, because they are often reluctant to talk about their feelings with their parents.

Signs your child may be depressed include:

  • no longer showing interest or taking pleasure in activities they used to enjoy
  • an inability to make or keep friends
  • lack of energy
  • problems sleeping or, alternatively, sleeping much more than usual
  • changes in their diet, either eating much more or much less than usual,
  • a sudden worsening of behaviour, such as getting into trouble at school or frequent rule breaking at home
  • a general lack of enjoyment in their day-to-day life

If you are concerned your child may be depressed, encourage them to talk about their feelings in a calm, non-judgemental way while stressing additional help and support is available if needed.

Mild to moderate depression in children and young people is often treated with talking therapies such as

cognitive behavioural therapy (CBT)

CBT is based on the principle that the way a person feels is partly dependent on the way that they think about things. It teaches children and young people to behave in ways that challenge negative thoughts, for example confronting feelings of hopelessness.

More severe depression is usually treated using a combination of talking therapies, such as CBT, and

antidepressant medications
, such as fluoxetine.

Important: Our website provides useful information but is not a substitute for medical advice. You should always seek the advice of your doctor when making decisions about your health.