Page last reviewed: 13/07/2011

Corticosteroids are any type of medication that contain steroids. Steroids are a type of hormone. Hormones are groups of powerful chemicals that have a wide range of effects on the body.

Corticosteroids are commonly used to:

  • reduce inflammation,
  • suppress the immune system, and
  • replace hormones in the body.

Corticosteroids should not be confused with anabolic steroids, which are sometimes used (illegally) by bodybuilders and athletes. Unlike anabolic steroids, corticosteroids do not affect muscle strength.

Types of corticosteroids

Corticosteroids are available in a number of different forms including:

  • tablets: oral corticosteroids,
  • sprays and inhalers: inhaled corticosteroids,
  • creams and lotions: topical corticosteroids, and
  • injections: these can be injected into the bloodstream (intravenous corticosteroids) or into an affected muscle or joint.

This section focuses on oral, injected and inhaled corticosteroids. See Useful links for more information about topical corticosteroids.

Page last reviewed: 13/07/2011

Corticosteroids are widely used in medicine. The three most common reasons to prescribe them are:

  • anti-inflammatory (to reduce inflammation),
  • immunosuppressant (to suppress the immune system), and
  • replacement therapy (to replace hormones that are not being produced by the body due to an underlying health condition).

Anti-inflammatory uses

Inflammation occurs when the immune system attempts to stop an infection spreading. It sends special inflammatory chemicals to the site of the infection, causing it to become inflamed and swollen.

However, in allergic reactions, the immune system thinks harmless substances such as pollen are harmful. This triggers the inflammation.

Corticosteroids can help to treat a range of allergic conditions including:

  • asthma,
  • allergic rhinitis (hayfever) and
  • urticaria (nettle rash).

Allergic skin conditions such as eczema are normally treated with topical corticosteroids (creams).

Immunosuppressant uses

With some illnesses, the immune system malfunctions and attacks healthy tissue. These are known as autoimmune conditions.

Corticosteroids can help to treat a range of these including:

  • rheumatoid arthritis, where the immune system attacks the joints,
  • lupus, where it attacks the skin and the joints,
  • Crohn's disease, where it attacks the digestive system, and
  • ulcerative colitis, where it attacks the colon.

Corticosteroids are also used to stop the immune system from rejecting a donated organ.

Replacement therapy

Corticosteroids are similar to the natural hormones that are produced by the adrenal glands. These hormones play an important role in regulating the body's metabolism (such as converting food into energy).

Corticosteroids are often used to treat Addison's disease. This is when the adrenal glands do not produce the right amount of hormones. Symptoms include:

  • severe fatigue,
  • hypotension (low blood pressure), and
  • the need to urinate often.


Joints are the connection point between two bones that allow movement.
The immune system is the body's defence system, which helps protect it from disease, bacteria and viruses.
Pain is an unpleasant physical or emotional feeling that your body produces as a warning sign that it has been damaged.
Corticosteroid is a naturally occurring hormone produced by the adrenal gland, or a synthetic hormone having similar properties. It is used to reduce inflammation, so reducing swelling and pain.
Body tissue is made up of groups of cells that perform a specific job, such as protecting the body against infection or storing fat.  
A rupture is a break or tear in an organ or tissue.
Inflammation is the body's response to infection, irritation or injury, which causes redness, swelling, pain and sometimes a feeling of heat in the affected area.
Kidneys are a pair of bean-shaped organs located at the back of the abdomen, which remove waste and extra fluid from the blood and pass them out of the body as urine.

Page last reviewed: 13/07/2011

At its most basic level, the immune system is made up of a number of specialised cells. These cells have several functions, one of which is to release chemicals that 'kick start' the inflammation.

Inflammation is useful for fighting infections, but can be troublesome for allergic or autoimmune conditions.

Corticosteroids can penetrate the wall of immune system cells (the cell membrane). Once inside the cell, corticosteroids are able to 'switch off' the genes responsible for releasing the inflammatory chemicals.

Page last reviewed: 13/07/2011

As corticosteroids are hormones, they can have a wide range of side effects. This is because hormones are powerful chemicals that influence many different processes, from the strength of your bones to your body weight.

If you are prescribed corticosteroids, the range and severity of the side effects will depend on two factors:

  • what type of corticosteroid medicine you are taking, and
  • how long you are using it for.

With inhaled corticosteroids or corticosteroids injected into a muscle or joint, the effects are focused in one part of the body. So any side effects also tend to be limited to a single part of the body.

With oral corticosteroids, or corticosteroids that are injected into the blood, the effects are spread throughout the body.

Long-term corticosteroid use is more likely to lead to hormonal changes within the body, which can cause a wide range of side effects.

Inhaled corticosteroids

The short-term use of inhaled corticosteroids means that most people will tolerate them well and have few or no side effects.

Long-term use, to treat a chronic condition such as asthma, can cause oral thrush (fungal infections that develop inside your mouth).

Rinsing your mouth out with water after using inhaled corticosteroids can help to prevent oral thrush.

Injected corticosteroids

Corticosteroids injected into muscles and joints may cause some pain and swelling at the site of the injection. However, this should pass within a few days.

Over time, repeated steroid injections into a muscle can weaken it.

Intravenous corticosteroids (injected into the blood) can cause side effects including:

  • stomach irritation, such as indigestion or heartburn,
  • tachycardia (rapid heartbeat),
  • nausea,
  • insomnia, and
  • a metallic taste in the mouth.

You may also experience mood changes. You could go from feeling very happy one minute to being irritable, depressed or restless the next.

Oral corticosteroids

Side effects of oral corticosteroids that are used on a short-term basis include:

  • an increase in appetite,
  • weight gain,
  • insomnia,
  • fluid retention, and
  • mood changes, such as feeling irritable, or anxious.

Side effects of oral corticosteroids used on a long-term basis (longer than three months) include:

  • osteoporosis (fragile bones),
  • hypertension (high blood pressure),
  • diabetes,
  • weight gain,
  • increased vulnerability to infection,
  • cataracts and glaucoma (eye disorders),
  • thinning of the skin,
  • bruising easily, and
  • muscle weakness.

Even if your side effects become troublesome, do not suddenly stop taking your medication. While you are taking steroids, your body will reduce the production of natural steroids.

If you do suddenly stop taking them, your body will not have enough steroids to work properly, and it is likely that you will have symptoms such as:

  • fatigue,
  • weight loss,
  • nausea,
  • dizziness,
  • vomiting,
  • diarrhoea, and
  • abdominal pain.

If a decision is made to end your treatment, your doctor will gradually reduce the amount of corticosteroids that you are taking. This will give your body the opportunity to increase its production of natural steroids.

Content provided by NHS Choices and adapted for Ireland by the Health A-Z.

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