We are using cookies to give you the best experience on our site. Cookies are files stored in your browser and are used by most websites to help personalise your web experience.

By continuing to use our website without changing the settings, you are agreeing to our use of cookies.

Find out more
You are here:
> > > > What are the possible risks and side-effects of leflunomide?

What are the possible risks and side-effects of leflunomide?

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

  • Try to avoid close contact with people with severe active infections.
  • For advice on avoiding infection from food, visit the NHS Choices Food Poisoning website. 


0800 5200 520

Our new helpline: Call us for free information, help and advice on your type of arthritis.

All calls are recorded for training and quality purposes

More Information Close
For more information, go to
Arthritis Research UK fund research into the cause, treatment and cure of arthritis. You can support Arthritis Research UK by volunteering, donating or visiting our shops.