How steroid injections work: Uses, benefits and side effects

26th May, 2021 • 11 min read

What are steroid injections?

Steroid injections – also known as corticosteroid injections or cortisone shots – are anti-inflammatory medicines that help treat many conditions. This includes joint pain caused by conditions like rheumatoid arthritis or inflammation in your soft tissues from a condition like tennis elbow. They can be used to treat inflammatory bowel disease too.

Steroids are hormones that are found naturally in your body. The steroids you’re given by a doctor are man-made versions of these hormones. They help bring down inflammation, which is the redness and swelling caused by your body’s healing response to damage or injury. They also help control your immune system’s response to illness or infection.

Steroids come in different forms such as tablets, creams and injections. A steroid injection is injected into your blood or a specific part of the body, like your ankle, knee or spine. It works by sending the medicine throughout your body or directly into a problem area to help with inflammation and pain, and to help a joint move more easily, for example.

Read on to discover which conditions steroid injections treat, how long they take to work, how long they last, who can safely have them and their possible side effects.

Which conditions do steroid injections treat?

Steroid injections reduce the inflammation of soft tissue or

joint pain
, caused by conditions like:

They can also be used for diseases that affect your immune system (autoimmune diseases), such as:

Steroid injections are used during cancer treatment too – they can help treat the cancer itself, bring down inflammation and help control the body’s immune response, for example, after a bone marrow transplant.

Conditions you can’t treat with steroid injections

When you get a steroid injection, it spreads through your body to help with inflammation. This kind of steroid, which includes injections and steroids you swallow, is called a systemic corticosteroid because it works on your whole body. But sometimes you may only need steroids to treat a very specific part of your body.

In such cases, steroid creams, drops or sprays (known as

topical corticosteroids
) may be best. They can help relieve the symptoms of certain skin problems, including
atopic eczema

Steroid nasal sprays
that you spray into your nose are best for dealing with conditions like
hay fever
non-allergic rhinitis
nasal polyps


steroid tablets
or liquids – known as oral steroids – spread through your whole body when you swallow them, so they’re used to treat inflammation throughout your body, rather than just in a specific area. Conditions they treat include:

Where are steroid injections injected and how do they work?

A steroid injection can only be given by a healthcare professional. The names of common kinds of steroid injections doctors use include hydrocortisone, triamcinolone and methylprednisolone. A steroid injection may have a local anaesthetic (numbing medication) in it too to help ease any pain you’re feeling.

A doctor can inject a steroid injection straight into:

  • your blood (an intravenous injection)
  • into a joint (an intra-articular injection)
  • into a muscle (an intramuscular injection)
  • into the spine (an epidural injection)
  • or around a tendon

When you have an injection into a joint, muscle, tendon or in your spine, it targets that specific problem area. But when you get a steroid injection into your blood, it spreads all around your body to help with inflammation (a systemic corticosteroid). These can help with autoimmune conditions, like multiple sclerosis (MS), which is when your immune system attacks your body by mistake.

Steroid injections are very different to

anabolic steroids
, which are medicines that are sometimes misused by athletes because they can increase athletic performance by copying the effects of the male hormone testosterone.

How do epidural steroid injections work?

There are many types of epidural steroid injections. They’re used to treat a sore back, neck or legs – they’re injected somewhere along the spinal cord, depending on where your pain is.

Injections in your neck are called cervical epidural injections, while injections in your lower back are called lumbar epidural injections. If you have one in the middle of your back, it’s known as a thoracic epidural injection.

These injections may also contain a local anaesthetic to numb the pain.

How long do steroid injections take to work and how long do they last?

When you have a steroid injection, it can take a few hours or a few days to start working. Some steroid injections will help with the pain and inflammation for a week, while longer-acting ones may work for months or sometimes up to a year. If a doctor has put a local anaesthetic in the steroid injection too, you will feel less pain immediately and this will usually last for a few hours.

Sometimes steroid injections don’t work or they only help for a short time. For the best treatment, use steroid injections with other treatments, like medicines for pain relief and

, depending on which condition you have.

You can have another steroid injection if the first injection doesn’t work. But there may be a limit to how many you can have in a 1-year period, as they may damage your tissues or weaken your bones. So, discuss whether you can have another one with a doctor if the effects are wearing off.

What are the side effects of steroid injections?

While generally safe, steroid injections might not be the safest option for you. Before getting one, tell a doctor if you:

  • have had an allergic reaction to any steroids before
  • have any other infection, including a joint or an eye infection
  • are pregnant, trying to fall pregnant or are breastfeeding
  • have any conditions, like
    high blood pressure
    (hypertension), or liver, heart or kidney problems
  • take any other medicines, like
    blood thinners (anticoagulants)
    , or herbal medicines, vitamins or supplements
  • recently had, or are about to have any vaccinations
  • have had a steroid injection recently – usually there needs to be at least a few weeks between injections
  • have had steroid injections in the same area in the past 12 months
  • have had or have
    or manic depression (
    bipolar disorder
    ), or if any of your close family has had these mental conditions
  • have recently been around someone with
    or measles (unless you’re sure you’re immune to these)

Like any medication, steroid injections may cause side effects, but most people don’t get side effects.

If you get an injection into a joint, the spine or through a muscle, common side effects may include:

  • pain or swelling for a few days around the body part that was injected – this usually goes away in a few days and you can take
    to help. But first speak to your doctor or pharmacist for guidance on how to safely get and use these medicines
  • bruising or bleeding under the skin that goes away
  • your face being red (flushed) for a few hours
  • if you have diabetes, your blood sugar levels may go up for a few days
  • if you have high blood pressure, it may go up for a few days
  • If you have an epidural injection, it may cause a bad headache that only gets better when you lie down

For steroid injections into the bloodstream, side effects may include:

  • appetite changes, like wanting to eat more
  • mood changes
  • trouble sleeping

When to see a doctor if you’ve had a steroid injection

See a doctor as soon as possible if:

  • your symptoms don’t get better, get worse or come back after treatment
  • you’re getting side effects from the medicine
  • you develop symptoms you didn’t expect, you feel generally unwell or are worried about your symptoms
  • you develop an infection that causes redness, swelling and pain after your injection
  • an epidural injection has brought on really bad headaches that don’t get better after lying down or on their own
  • you’re depressed and having suicidal thoughts, or if you’re feeling high or anxious or having mood swings, you start seeing or hearing things that aren’t there, or having strange or bad thoughts – this could be signs of a mental health problem
  • you get a puffy, rounded face and start gaining weight in your upper back or belly – these can be signs of
    Cushing's syndrome
  • you get any changes to your eyesight

You should call an ambulance or go to an emergency department if:

Your health questions answered

How will I feel after a cortisone injection?

You probably won’t have any side effects after a cortisone injection, as most people don’t. But some people may get pain, swelling or bruising in the area where the injection was given, like in the joint. This usually goes away after a day or 2. You should rest for 24 hours after getting the injection, so avoid any heavy exercise. You may want to take simple painkillers, but first speak to a doctor or pharmacist for guidance on how to safely get and use these medicines. If you have symptoms for longer than this, or notice any other worrying symptoms, including really bad headaches that don’t go away after a few days or an infection, speak to a doctor. After a cortisone injection, your joint may feel better for many months and sometimes as long as a year.

How long do steroid injections take to work?

“If your injection contains local anaesthetic, your pain may start to improve after a few minutes. However, the pain may return once the local anaesthetic wears off. The steroid part of the injection usually starts to work after 24 to 48 hours, but sometimes it can take longer. In some people it can take a few days or even weeks before any improvement is noticed. If you’re concerned about the length of time your steroid injection is taking to work, you should discuss this with a doctor.” – Answered by

Dr Aleem Qureshi
from the Healthily Medical Team

Why is pain worse after a steroid injection?

After a cortisone injection, some people may feel more pain in the joint that was injected in the first 24 hours – this is known as a cortisone flare, but it’s very rare. It can also cause build-up in the fluid around the joint. A cortisone flare usually goes away in a few days and you can manage it with simple painkillers, but first speak to a doctor or pharmacist for guidance on how to safely get and use these medicines. Other rare side effects could cause pain too, including headaches or an infection that causes redness, swelling and pain. See a doctor immediately if you think you have an infection or have other side effects.

Key takeaways

  • a steroid injection reduces inflammation in the body and can be used to treat conditions like back pain, arthritis, tennis elbow and sciatica
  • steroid injections can be given into the joint, the blood, a muscle or the spine
  • steroid injections can help reduce pain and inflammation for a few weeks to many months
  • for the best treatment, use steroid injections with other treatments, like medicines for pain relief and physiotherapy
  • most people don’t get any side effects from steroid injections, but if they do, they’re usually mild and go away after a few days. But, if they don’t go away or are very bad, see a doctor

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.