What is sulfasalazine and how is it used?

Sulfasalazine is a type of drug known as a disease-modifying antirheumatic drug (DMARD). It works by modifying the underlying disease process to reduce inflammation, pain and swelling in your joints.

It can be used to treat:

  • rheumatoid arthritis
  • psoriatic arthritis
  • arthritis associated with inflammatory bowel disease.

It may be prescribed by your GP or a consultant rheumatologist.

Sulfasalazine doesn’t work immediately. It may be at least 12 weeks before you notice any benefit.

You shouldn’t take sulfasalazine if you’re known to have an allergy to salicylates (e.g. aspirin) or to sulphonamides (a certain type of antibiotic).

When and how do I take sulfasalazine?

Sulfasalazine tablets should be taken with a glass of water. Sulfasalazine is generally prescribed as Salazopyrin EN-Tabs – these tablets are specially coated so that they don’t dissolve quickly in your stomach. They should be swallowed whole and not crushed or chewed.

Your doctor will advise you on the correct dose – usually a low dose at first (e.g. one 500 mg tablet daily). This is usually increased gradually over a period of about four weeks – typically to two 500 mg tablets taken twice daily. The dose may be adjusted according to the severity of your symptoms.

Because it’s a long-term treatment, it’s important to keep taking sulfasalazine (unless you have severe side-effects):

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

Possible risks and side-effects

The most common side-effects of sulfasalazine are feeling sick (nausea), diarrhoea, stomach pain, dizziness, headache and skin rashes. These side-effects usually occur during the first three months of treatment and often clear up if the dose is reduced. You may be able to increase the dose again after a time if your tolerance improves and if the sulfasalazine is helping your arthritis symptoms.

You should tell your doctor or nurse specialist straight away if you develop any of the following after starting sulfasalazine:

  • a sore throat
  • a fever
  • any other symptom of infection
  • unexplained bruising
  • any other new symptoms or anything else that concerns you.

Your urine may change colour (to orange) with sulfasalazine but this is nothing to worry about. Sulfasalazine may also stain soft contact lenses (and tears) yellow.

Taking sulfasalazine can affect your blood count or your liver, but these effects can be picked up at an early stage by regular blood tests. Your doctor will arrange for you to have a blood test before you start treatment and then regular checks while you’re on sulfasalazine. You may be asked to keep a record of your blood test results in a booklet, and you should take it with you when you visit your GP or the hospital.

You must not take sulfasalazine unless you’re having regular blood tests and the results are being checked.

Taking other medicines

Check with your doctor before starting any new medications, and remember to mention you’re on sulfasalazine if you’re treated by anyone other than your usual healthcare team.

  • You can carry on taking non-steroidal anti-inflammatory drugs (NSAIDs) or painkillers if needed, unless your doctor advises otherwise. If sulfasalazine works for you, you may be able to reduce your NSAIDs or painkillers after a time.
  • Don’t take over-the-counter preparations or herbal remedies without discussing this first with your doctor, rheumatology nurse specialist or pharmacist.


You can have vaccinations while on sulfasalazine.


There’s no particular reason to avoid alcohol while on sulfasalazine.

Fertility, pregnancy and breastfeeding

It’s safe for women to continue to use sulfasalazine when trying for a baby and during pregnancy. You should also take folic acid tablets (5 mg daily), as sulfasalazine can reduce levels of folic acid in the body. It’s often recommended to continue sulfasalazine through pregnancy to prevent a flare-up of your disease. You should talk to your doctor as soon as possible if you’re planning a family, or if you become pregnant while taking sulfasalazine.

Sulfasalazine can cause a fall in sperm count, leading to a temporary decrease in male fertility, but must not be relied upon for contraception. This effect is reversed if treatment is stopped, and research hasn’t shown this to be a problem. You should discuss this with your rheumatologist, but current guidelines advise that it’s not necessary for men to stop sulfasalazine before trying to father a baby. However, if you’re on sulfasalazine and you’ve been trying for a baby for a year or more while on sulfasalazine you should discuss this with your doctor and arrange to see a fertility specialist to rule out other problems.

Sulfasalazine is considered safe to use while you’re breastfeeding unless the baby is premature or at risk of jaundice. Speak to your rheumatology team about this if you have any concerns.

Further information

When treatment with sulfasalazine is successful, pain, joint swelling and stiffness will be reduced and this may slow down or stop the development of joint damage.

If you would like any further information about sulfasalazine or have any concerns about your treatment, you should discuss this with your doctor, rheumatology nurse specialist or pharmacist. They will also be able to advise on possible alternatives if sulfasalazine doesn’t suit you.

Reducing the risk of infection

Arthritis Research UK publishes a wide range of information on arthritis including conditions, treatments, surgery and living with arthritis. You can order these free of chargeby visiting our website, calling the number on the back of this leaflet or writing to us.

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