How serious are insect bites?
Insect bites and stings are common and usually cause only minor irritation. However, some stings can be painful and trigger a serious allergic reaction.
An insect bites you by making a hole in your skin to feed. Most insects sting as a defence by injecting venom into your skin.
How can I tell if I have an insect bite or sting?
When an insect bites, it releases saliva that can cause skin around the bite to become red, swollen and itchy. The venom from a sting often also causes a swollen, itchy, red mark (a weal) to form on the skin. This can be painful, but is harmless in most cases. The affected area will usually remain painful and itchy for a few days.
The severity of bites and stings varies depending on the type of insect and sensitivity of the person.
In rare cases, some people can have a serious allergic reaction (anaphylaxis) to a bite or sting that requires immediate medical treatment.
Read more about the symptoms of insect bites and stings.
Should I see a doctor?
See your doctor if you have a lot of swelling and blistering, or if there is pus, which indicates an infection.
Call for an ambulance or medical professional immediately if you have the following symptoms:
- wheezing or difficulty breathing
- nausea, vomiting or diarrhoea
- a fast heart rate
- dizziness or feeling faint
- difficulty swallowing (dysphagia)
- confusion, anxiety or agitation
Read more about complications of an insect bite or sting.
Treating insect bites and stings
Most bites and stings are treated by:
- washing the affected area with soap and water
- placing a cold compress (a flannel or cloth soaked in cold water) over the area to reduce swelling
If you have a more serious reaction, your doctor may prescribe other medication or refer you to an allergy clinic for immunotherapy.
Read more information about treating insect bites and stings.
Preventing insect bites and stings
You are more likely to be bitten or stung if you work outdoors or regularly take part in outdoor activities, such as camping or hiking.
Wearing insect repellent and keeping your skin covered will help avoid a bite or a sting.
Try not to panic if you encounter wasps, hornets or bees and back away slowly (do not wave your arms around or swat at them).
Read more about preventing insect bites and stings.
There is a risk of catching diseases from insect bites, such as malaria, in other parts of the world such as:
- South America
It is important to be aware of any risks before travelling and get any necessary medication or vaccination.
What are the signs of an insect bite or sting?
An insect bite or sting often causes a small lump to develop, which is usually very itchy.
A small hole, or the sting itself, may also be visible. The lump may have an inflamed (red and swollen) area around it that may be filled with fluid. This is called a weal.
Insect bites and stings usually clear up within several hours and can be safely treated at home.
Types of insect bite
The symptoms that can occur from different types of insect bites are listed below.
Midges, mosquitoes and gnats
Bites from midges, mosquitoes and gnats often cause small papules (lumps) to form on your skin that are usually very itchy. If you are particularly sensitive to insect bites, you may develop:
- bullae (fluid-filled blisters)
- weals (circular, fluid-filled areas surrounding the bite)
Mosquito bites in certain areas of tropical countries can cause malaria.
Flea bites can be grouped in lines or clusters. If you are particularly sensitive to flea bites, they can lead to a condition called papular urticaria (where a number of itchy red lumps form). Bullae may also develop.
Fleas from cats and dogs can often bite below the knee, commonly around the ankles. They may also affect the forearms if you have been stroking or holding your pet.
A bite from a horsefly can be very painful. As well as the formation of a weal around the bite, you may experience:
- urticaria – a rash of weals (also called hives, welts or nettle rash)
- angioedema – itchy, pale pink or red swellings that often occur around the eyes and lips for short periods of time
Horseflies cut the skin when they bite, rather than piercing it, so horsefly bites can take a long time to heal and can cause an infection.
Bites from bedbugs are not usually painful, and if you have not been bitten by bedbugs before, you may not have any symptoms. If you have been bitten before, you may develop intensely irritating weals or lumps.
Bedbug bites often occur on your:
Read more information about bedbugs.
The Blandford fly
The Blandford fly (sometimes called blackfly) is found in parts of the United Kingdom, including:
- East Anglia
Blandford fly bites are common during May and June. They often occur on the legs and are very painful. They can produce a severe, localised reaction (a reaction that is confined to the area of the bite), with symptoms such as:
- a high temperature of 38C (100.4F) or over
- joint pain
Types of arachnid bites
Tick bites are not usually painful and sometimes only cause a red lump to develop where you were bitten. However, in some cases they may cause:
Ticks can carry a bacterial infection called Borrelia burgdorferi, which causes Lyme disease. If Lyme disease is not treated, it can be serious.
Mites cause very itchy lumps to appear on the skin and can also cause blisters. If the mites are from pets, you may be bitten on your abdomen (tummy) and thighs where the pet has been sitting on your lap. Otherwise, mites will bite any uncovered skin.
Spider bites are rare in the UK, and tend to be more likely abroad, through keeping an exotic pet, or handling goods from overseas.
Spider bites leaves small puncture marks on the skin and can cause:
In severe cases a spider bite may cause nausea, vomiting, sweating and dizziness. Very rarely, a spider bite may cause a severe allergic reaction.
Types of insect stings
Wasps and hornets
A wasp or hornet sting causes a sharp pain in the area you are stung and usually lasts just a few seconds.
A swollen, red mark will often then form on the skin, which can be itchy and painful.
At first, a bee sting feels similar to a wasp sting.
However, if you are stung by a bee, it will leave its sting and a venomous sac in the wound. You should remove this immediately by scraping it out using something with a hard edge, such as a bank card.
Do not pinch the sting out with your fingers or tweezers because you may spread the venom.
Most people will not have severe symptoms after an insect bite or sting but some people can react badly to them. You are more likely to have an allergic reaction if you are stung by an insect.
The reaction can be classed as:
- a minor localised reaction – this is normal and does not require allergy testing, although the affected area will often be painful for a few days
- a large localised reaction (LLR) – this can cause other symptoms such as swelling, itching and a rash
- a systemic reaction (SR) – this often requires immediate medical attention as it can cause a potentially life-threatening allergic reaction (anaphylaxis)
Although insect bites and stings are a common cause of anaphylaxis, it is rare to experience anaphylaxis after an insect sting, and it is rarely fatal.
Large localised reactions and systemic reactions are described in more detail below.
Large localised reaction (LLR)
If you have an LLR after being bitten or stung by an insect, a large area around the bite or sting will swell up. The area may measure up to 30cm (12in) across, or your entire arm or leg could swell up.
The swelling will usually last longer than 48 hours but should start to go down after a few days. This can be painful but the swelling will not be dangerous unless it affects your airways.
If you are bitten or stung many times by one or more insects, your symptoms will be more severe because a larger amount of venom will have been injected.
You may have an LLR several hours after being bitten or stung. This could include:
- a rash
- painful or swollen joints
Systemic reaction (SR)
It is more likely that someone will have an SR if they have been bitten or stung before (sensitised), especially if it was recently. People who have been sensitised to bee stings are more likely to have an SR than people who are stung by wasps.
If you have any of the following symptoms after being bitten or stung call emergency services immediately and ask for an ambulance:
- wheezing, hoarseness or difficulty breathing
- nausea, vomiting or diarrhoea
- a fast heart rate
- dizziness or feeling faint
- difficulty swallowing (dysphagia)
- a swollen face or mouth
- confusion, anxiety or agitation
It is rare for an SR to be fatal, especially in children, although someone with an existing heart or breathing problem is at increased risk.
Read information about treating insect bites and stings.
Treating an insect bite or sting
Most insect bites and stings cause small reactions that are confined to the area of the bite (localised reactions). They can usually be treated at home.
However, if your symptoms are severe, see your doctor as soon as possible.
Removing a sting
As soon as you have been stung by a bee, remove the sting and the venomous sac if it has been left in the skin. Do this by scraping it out, either with your fingernails or using something with a hard edge, such as a bank card.
When removing the sting, be careful not to spread the venom further under your skin and do not puncture the venomous sac.
Do not pinch the sting out with your fingers or a pair of tweezers because you may spread the venom. If a child has been stung, an adult should remove the sting.
Wasps and hornets do not usually leave the sting behind, so could sting you again. If you have been stung and the wasp or hornet is still in the area, walk away calmly to avoid being stung again.
Most insect bites and stings cause itching and swelling that usually clears up within several hours.
Minor bites and stings can be treated by:
- washing the affected area with soap and water
- placing a cold compress (a flannel or cloth cooled with cold water) over the affected area to reduce swelling
- not scratching the area because it can become infected (keep children's fingernails short and clean)
See your doctor if the redness and itching gets worse or does not clear up after a few days.
If the bite or sting is painful or swollen, you can also:
- wrap an ice pack (such as a bag of frozen peas) in a towel and place it on the swelling
- take painkillers, such as paracetamol or ibuprofen (children under 16 years old should not be given aspirin)
- use a spray or cream that contains local anaesthetic, antihistamine or mild hydrocortisone (1%) on the affected area to prevent itching and swelling
- take an antihistamine tablet to help reduce swelling (antihistamine tablets are available on prescription or from pharmacies)
If local swelling is severe, your doctor may prescribe a short course of oral corticosteroids, such as prednisolone, to take for three to five days.
If you have an allergic reaction after a bite or sting, even if it is just a skin rash (hives), you may be prescribed an adrenaline pen (called an auto-injector) by your doctor and shown how to use it. You will also be referred to an allergy clinic to see an immunologist for further tests and treatment.
If you develop blisters after being bitten by an insect, do not burst them because they may become infected. Blisters do not often cause pain unless they rupture (burst), exposing the new skin underneath. If possible, use an adhesive bandage (plaster) to protect the blistered area.
See your doctor if the bite or sting fills with pus and feels tender to touch, your glands swell up and you feel unwell with flu-like symptoms.
Your doctor may prescribe oral antibiotics (medicines to treat infections caused by bacteria). You will need to take these as instructed, usually two or four times a day for seven days.
If you have swelling or itching anywhere else on your body after being bitten or stung, or if you are wheezing or have difficulty swallowing, you will need emergency medical treatment. Call an emergency medical professional immediately.
If you have the symptoms of a systemic reaction (SR), it could lead to anaphylactic shock. If you experience anaphylaxis, you may need to have an adrenaline injection, antihistamines, oxygen or an intravenous drip (a drip directly into a vein).
If previous insect bites or stings have caused a large skin reaction, such as redness and swelling of over 10cm (4 inches) in diameter, your doctor may refer you to an allergy clinic. The criteria for referring someone to an allergy clinic may vary depending on what is available in your local area.
Immunotherapy (desensitisation or hyposensitisation) is a possible treatment option if you are allergic to insect bites or stings, although it is more commonly used for wasp or bee stings. It involves being injected with small doses of venom every week and being observed to check for an allergic reaction.
Your body soon becomes used to the venom (desensitised) and will start to make antibodies to prevent further reactions.
When a high enough dose has been reached, the injections will be given monthly and could last for a further two or three years.
Your immunologist will decide how much venom is injected and how long the injections need to continue for. This will depend on your initial allergic reaction and your response to the treatment.
Read about treating allergies for more information about immunotherapy.
If you have been bitten by a tick (a small arachnid), remove it as soon as possible to reduce the risk of getting a tick-borne infection, such as Lyme disease (a bacterial infection that causes a rash).
To remove the tick:
- Use tweezers, wear gloves or cover your fingers with tissue to avoid touching the tick.
- Grab the tick as close to the skin as you can, and gently pull straight up until all parts are removed.
- Do not twist or jerk the tick as you are removing it because this may cause the mouthparts to break off and remain in your skin once the tick has been removed.
- Wash your hands with soap and water.
- Using petroleum jelly, alcohol or a lit match to remove a tick does not work.
After the tick has been removed, clean the tick bite with soap and water or an antiseptic, such as an iodine scrub.
Do not scratch the bite because this will cause further swelling and increase the chance of infection. Most tick bites will heal within three weeks. See your doctor if you develop:
- a rash
- a temperature of 38C (100.4F) or over (fever)
You may need antibiotics to prevent Lyme disease.
Can insect bites and stings be prevented?
There are a number of precautions that you can take to avoid being bitten or stung by insects. It is particularly important to follow this advice if you have had a bad reaction to an insect bite or sting in the past.
Some of the precautions that you can take to minimise your risk of being bitten or stung by an insect are listed below.
- Move away slowly without panicking if you encounter wasps, hornets or bees. Do not wave your arms around or swat at them.
- Cover exposed skin. If you are outside at a time of day when insects are particularly active, such as sunrise or sunset, cover your skin by wearing long sleeves and trousers.
- Wear shoes when outdoors.
- Apply insect repellent, particularly in summer or early autumn when stings are most likely to occur. This should be applied to exposed areas of skin. Repellents that contain diethyltoluamide (DEET) are considered most effective.
- Avoid using products with strong perfumes such as soaps, shampoos and deodorants, because they can attract insects.
- Avoid flowering plants, outdoor areas where food is served, rubbish and compost areas. Regularly and carefully remove any fallen fruit in your garden, and keep a well-fitting lid on any dustbins.
- Never disturb insect nests. If a nest is in or near your house, arrange to have it removed. Wasps build nests in sheltered areas including trees and roof spaces.
- Avoid camping near water, such as ponds and swamps, because mosquitoes and horseflies are commonly found near water.
- Keep food and drink covered when eating or drinking outside, particularly sweet things. Wasps or bees can also get into open drink bottles or cans you are drinking from.
- Keep doors and windows closed or put thin netting or door beads over them to prevent insects getting inside the house. Also keep the windows of your car closed to stop insects getting inside.
Ticks are small arachnids mainly found in woodland areas. They attach to your skin, suck your blood and can be responsible for Lyme disease.
The best ways to avoid ticks include:
- being aware of ticks and the areas where they usually live
- wearing appropriate clothing in tick-infested areas (a long-sleeve shirt and trousers tucked into your socks)
- wearing light-coloured fabrics that may help you spot a tick on your clothes
- using insect repellents
- inspecting your skin for ticks, particularly at the end of the day, including your head, neck and skin folds (armpits, groin, and waistband)
- checking your children’s head and neck areas, including their scalp
- making sure ticks are not brought home on your clothes
- checking pets do not bring ticks indoors in their fur
It is also important to remove any ticks you find as soon as possible. Read more about treating insect bites and stings for information on the safest way to remove a tick.
If you are bitten by fleas, mites or bedbugs, you may have an infestation in your home. Try to find the source of the infestation and then take steps to eliminate it.
Signs of an infestation
The following are signs of an infestation:
- fleas or flea faeces (stools) in your animal’s fur or bedding are a sign of fleas
- crusting on your dog’s fur is a sign of fleas
- excessive scratching and grooming are a sign of fleas in your cat
- dandruff (flakes of skin) on your cat or dog is a sign of mites
- spots of blood on your bed sheets are a sign of bedbugs
- an unpleasant almond smell is a sign of bedbugs
If you are unsure whether your pet has fleas, speak to your veterinary surgeon.
Eliminating an infestation
Once you have identified the cause of the infestation, you will need to eliminate it.
For flea infestations:
- treat the animal, its bedding, household carpets and soft furnishings with an insecticide
- thoroughly vacuum your carpets and soft furnishings
For mite infestations, seek advice from your vet as aggressive treatment is required.
For bedbug infestations, your home will need to be thoroughly treated with an insecticide by a reputable pest control company.
Read more about bedbugs including how to spot them and getting rid of them.
Seek medical advice before travelling to a tropical area where there is a risk of catching malaria. You may need to take antimalarial tablets to avoid becoming infected.
Read more information about preventing malaria.
When you reach your destination, make sure your accommodation has insect-proof screen doors and windows that close properly. Sleeping under a mosquito net and spraying rooms with insecticide will also help stop you being bitten.
Complications of insect bites and stings
A number of complications can develop after you are bitten or stung by an insect.
Secondary bacterial infections are a common complication of insect bites and stings. They include:
- impetigo – a highly contagious bacterial infection that causes sores or blisters
- cellulitis – an infection that makes your skin red, swollen and painful
- folliculitis – inflammation (redness and swelling) of one or more hair follicles (the small hole in your skin that an individual hair grows out of)
- lymphangitis – an infection that causes red streaks in your armpit or groin and swollen lymph nodes (small glands that are part of the immune system)
An infection may occur if you scratch an insect bite or sting, or it may be introduced at the time you are bitten.
Infections are usually treated with antibiotics.
Lyme disease is an infection caused by a species of tick known as Ixodes ricinus. Ticks are not strictly insects, but small arachnids.
The initial infection is characterised by a red rash that gradually expands outwards from the site of the bite. Antibiotics are usually used to treat the infection.
If untreated, the long-term effects of Lyme disease include problems with the nervous system such as:
- facial palsy – weakness of the facial muscles that causes drooping of one or both sides of the face
The condition can also damage the joints, which can lead to arthritis and heart problems (occasionally), such as inflammation of the heart muscle (myocarditis) and inflammation of the thin, two-layered, sac-like tissue that surrounds the heart (pericarditis).
West Nile virus
West Nile virus is an infection with flu-like symptoms spread by mosquitoes.
Malaria is a tropical disease caused by an infection of the red blood cells. It can be transmitted to humans by the bite of an infected mosquito.