What is leflunomide?

Leflunomide (or Arava™) is a type of disease-modifying anti-rheumatic drug (DMARD).

DMARDs like leflunomide dampen down underlying disease processes, rather than simply treating your symptoms.

Leflunomide reduces the activity of your immune system (your body's defence system), which may be overactive in some conditions. This means it can reduce the inflammation that causes:

  • pain
  • swelling
  • stiffness.

Leflunomide is always used with care because of its effects on the immune system.


Leflunomide is used to treat rheumatoid arthritis and other types of auto-immune disease.

Will I need any special checks before I take leflunomide?

It’s important that you have a blood test and blood pressure measurement before starting treatment.

Are there any alternatives to leflunomide?

A number of other drugs are used in the treatment of rheumatoid arthritis and related conditions. Your doctor or rheumatology nurse will discuss these other options with you.

How is it taken?

Leflunomide tablets are taken once a day. Swallow the tablets whole without crushing or chewing them. It's best to take them at the same time every day. You can take them with or without food.

Your doctor will advise you about what dose you should take – usually either 10 mg or 20 mg a day.

How long does it take to work?

Leflunomide doesn't work immediately. It may take six weeks or more for you notice any benefit and several months before you feel the full effect. Because it's a long-term treatment it's best to keep taking leflunomide (unless you have severe side-effects):

  • even if it doesn't seem to be working at first
  • even when your symptoms improve (to help keep your condition under control).

Side-effects and risks

The most common side-effects of leflunomide are:

  • feeling sick (nausea), stomach pain or diarrhoea
  • mouth ulcers
  • weight loss
  • headaches or dizziness
  • weakness or pins and needles
  • dry skin or a rash
  • a slight rise in blood pressure.

Hair loss is a rare, and usually minor, side-effect.

Leflunomide can affect the blood count by reducing the number of blood cells you make, which can make you more likely to pick up infections. It can also affect the liver. You'll have regular blood tests to check for early signs of these side-effects.

What should I do if I experience side-effects?

Tell your doctor or rheumatology nurse straight away if you develop any signs of infection (such as a sore throat or fever) or have unexplained bruising or bleeding, breathlessness, jaundice (yellow skin or eyes) or any other new symptoms that concern you.

You should also see your doctor if you develop chickenpox or shingles or come into contact with someone who has chickenpox or shingles. These illnesses can be severe if you're on leflunomide. You may need antiviral treatment, and your leflunomide may be stopped until you're better.

If you have severe side-effects, your doctor may suggest having a wash-out treatment which will help remove the leflunomide from your body more quickly.

Reducing the risk of infection

Effects on other treatments

Can I take other medicines alongside leflunomide?

You may be prescribed leflunomide alongside other drugs. Discuss any new medications with your doctor because some drugs interact with leflunomide. Examples include:

  • warfarin (which thins the blood)
  • phenytoin (which is used in epilepsy).

Always tell any other doctor treating you that you’re on leflunomide.

  • You can carry on taking a non-steroidal anti-inflammatory drug (NSAID) or painkillers, if needed, unless your doctor advises otherwise.
  • Don't take over-the-counter preparations or herbal remedies without discussing this first with your healthcare team.

If you need to start another treatment which could interact with leflunomide, your doctor may suggest having a wash-out treatment to help remove the leflunomide from your body.


If you're on leflunomide it's recommended that you don't have live vaccines such as yellow fever or shingles. However, sometimes, a live vaccine may be necessary (for example rubella immunisation in women of childbearing age). In this case your doctor will discuss the possible risks and benefits of the immunisation with you.

Pneumococcal vaccine (which gives protection against the most common cause of pneumonia) and yearly flu vaccines are safe and recommended.

Having an operation

If you're going to have an operation, discuss this with your rheumatology team. They may advise you to stop the leflunomide for a time before and after surgery.


Leflunomide and alcohol may interact and damage your liver.

You should only drink alcohol in small amounts – no more than 4–8 units per week.

Fertility, pregnancy and breastfeeding

If you’re thinking of having a baby, you should discuss your medications with your rheumatology team beforehand.

From the limited evidence available, leflunomide doesn't appear to be harmful in human pregnancy. But because the evidence is so limited, both men and women who are taking leflunomide are advised to use contraception.

Women who want to have a baby are usually advised to stop taking leflunomide and have a special wash-out treatment before trying to become pregnant. If you prefer not to have the wash-out treatment your doctor may advise you to continue using contraception for up to two years after stopping leflunomide.

If you become pregnant while taking leflunomide, stop the drug and speak to your doctor as soon as possible about having the wash-out treatment. As long as you stop the drug and have the wash-out treatment it's very unlikely that leflunomide will have caused any harm to your baby.

As a precaution, men taking leflunomide may also be advised to have the wash-out treatment before trying to father a child.

Breastfeeding isn’t recommended if you’re on leflunomide because it may pass into your breast milk and could affect your baby.

What is a wash-out treatment and why might I need it?

Leflunomide can remain in the body for up to a year after you stop taking it.

In some circumstances it's recommended that leflunomide is eliminated from the body more quickly for example if:

  • you become pregnant
  • you have severe side-effects from leflunomide
  • you need to start another treatment that could interact with leflunomide.

A wash-out treatment will help to remove leflunomide from your body more quickly than usual. This involves taking a drug called cholestyramine for 11 days. You may have blood tests to check that the level of leflunomide in your body is falling.