Steroids, also called corticosteroids, are anti-inflammatory medicines used to treat a range of conditions.

They're different from anabolic steroids, which are often used illegally by some people to increase their muscle mass.

Steroids come in many different forms.

The main types are:

• tablets and liquids – such as prednisolone
• inhalers – such as beclometasone and fluticasone
• nasal sprays – such as beclometasone and fluticasone
• injections (given into joints, muscles or blood vessels) – such as methylprednisolone
• creams, lotions and gels – such as hydrocortisone for skin

Most steroids are only available on prescription, but a few (such as some creams or nasal sprays) can be bought from pharmacies and shops.

Steroids do not tend to cause significant side effects if they're taken for a short time or at a low dose.

But sometimes they can cause unpleasant side effects, such as an increased appetite, mood changes and difficulty sleeping (insomnia). This is most common with steroid tablets.

The side effects will usually pass once you finish the treatment, but do not stop taking your medicine without speaking to your doctor. Your doctor will advise you on how to gradually reduce your dose if necessary. Stopping a prescribed course of medicine suddenly can cause further unpleasant side effects (withdrawal symptoms).

Read more about the side effects of:

• steroid tablets
• steroid inhalers
• steroid nasal sprays
• steroid injections
• steroid creams

You can report any suspected side effect to the Yellow Card Scheme.

If you need to take high doses of steroids you may need to carry a blue steroid treatment card or a red steroid emergency card. Ask your doctor about these.

The blue steroid treatment card has details of your treatment and how you can reduce the risks of side effects.

The red steroid emergency card warns healthcare professionals that you're taking steroids in case you need emergency treatment.

If you need any medical or dental treatment, show your blue or red steroid card to the doctor, dentist or pharmacist so that they know you're taking steroids.

Steroids can be used to treat a wide range of conditions, including:

• asthma and chronic obstructive pulmonary disease (COPD)
• hay fever
• severe hives
• eczema
• painful joints or muscles – such as arthritis, tennis elbow and frozen shoulder
• pain caused by an irritated or trapped nerve – such as severe sciatica
• inflammatory bowel disease – such as Crohn's disease
• lupus
• multiple sclerosis (MS)

Steroids are a man-made version of hormones normally produced by the adrenal glands which are 2 small glands found above the kidneys.

Steroids reduce redness and swelling (inflammation). This can help with inflammatory conditions such as asthma and eczema.

Steroids also reduce the activity of the immune system, which is the body's natural defence against illness and infection.

This can help treat autoimmune conditions, such as rheumatoid arthritis or lupus, which are caused by the immune system mistakenly attacking the body.