Sulfasalazine (Pyralin EN, Salazopyrin EN)


What is sulphasalazine?

Sulfasalazine (brand names Pyralin EN, Salazopyrin, Salazopyrin EN) is a medicine used to treat rheumatoid arthritis. It can also be used to treat other diseases such as psoriatic arthritis, Crohn’s disease and ulcerative colitis.

It is a combination of an aspirin-like anti- inflammatory component and a sulphur antibiotic-like component.

It is not clear how sulfasalazine works. It appears to have anti-inflammatory effects and to reduce the activity of the immune system. In rheumatoid arthritis, these actions help to reduce pain, inflammation and joint swelling. It also limits damage to the joints and helps to prevent disability in the long term.

Because sulfasalazine acts to reduce the damage to the joints, rather than just relieve the pain, it belongs to the group of medicines called disease modifying antirheumatic drugs (DMARDs).


What benefit can you expect from your treatment?

Between 50 and 70% of people treated with sulfasalazine respond well to the treatment.

Sulfasalazine does not work straight away. Improvement in symptoms occurs gradually from about 6 to 12 weeks after commencing treatment.

Other medicines may be given to improve your symptoms while waiting for the sulfasalazine to work.


How is sulfasalazine taken?

Sulfasalazine is taken by mouth in tablet form. It is usually taken twice a day but may also be taken as a single daily dose.

There are two types of tablet available – plain and enteric coated. The enteric coated tablet (Pyralin EN and Salazopyrin EN) is usually prescribed as it may have fewer side effects.

The enteric coated tablets should be taken with or after meals with a glass of water. They should not be broken, crushed or chewed.

Treatment is started slowly, with one tablet (500mg) or two tablets a day. The dose is increased each week. The usual maintenance dose is two tablets twice a day.

Sulfasalazine may be used with other arthritis medicines including:

  • other DMARDs such as methotrexate
  • biologic and targeted synthetic DMARDs
  • corticosteroid medicines such as prednisolone or cortisone injections into the joint
  • anti-inflammatory medicines (NSAIDs) such as naproxen (Naprosyn) or ibuprofen (Brufen/Nurofen)
  • simple pain medicines such as paracetamol.

How long is treatment continued?

Treatment with sulfasalazine may be continued indefinitely as long as it is effective and no serious side effects occur.

If you stop sulfasalazine treatment for more than a few weeks there is a risk that your condition may worsen. Do not stop taking sulfasalazine unless advised by your doctor or unless serious side effects develop.


Are there any side effects?

You might experience side effects with your treatment. Tell your doctor if you are concerned about possible side effects.

A reduction in dose may minimise side effects so that you can continue to take this treatment. Your doctor will advise on any dose changes that are necessary.

Most common possible side effects

  • The most common side effects are loss of appetite and nausea (feeling sick) and vomiting. These occur early in the treatment and affect up to a third of people. These can be minimised by starting with a low dose and gradually increasing it.
  • Reflux, diarrhoea and abdominal pain are also quite common.
  • Sulfasalazine usually causes your urine and perspiration to take on an orange colour. This will wash out of most clothing, but will stain some nylon fabrics. Contact lenses, particularly extended wear soft lenses, may be permanently stained. These are normal changes and do not mean you are having a reaction to the medicine.
  • About 10% of people taking sulfasalazine may develop a headache or slight dizziness. Reducing the dose may reduce these effects.
  • All ‘sulphur’ containing medicines can cause skin rashes, which may be itchy, as well as mouth ulcers. This can occur in about 10% of people. It usually resolves quite quickly once the medicine is stopped. If you have had problems in the past with medicines containing sulphur e.g. Bactrim or Septrim, or you think you may have had problems, let your doctor know.
  • ‘Sulphur’ drugs can also cause a temperature, which is referred to as a ‘drug fever’. Tell your doctor immediately if this occurs.

Less common or rare side effects

  • Ringing in the ears, difficulty with thinking, personality changes and depression are occasional side effects.
  • Some people may notice an increased sensitivity to the sun. It is a good idea to apply sunscreen and to wear a hat when in the sun.
  • Blood counts: Sulfasalazine can cause a drop in the number of white blood cells, which are needed to fight infection. Regular blood tests aim to pick this problem up early. If you develop a sore mouth, mouth ulcers, infection or fever tell your doctor straight away.
  • People with an inherited blood disorder called G6PD deficiency have a significant risk of blood count problems when taking sulfasalazine. This disorder is most common in people originating from Africa (including African-Americans), the Mediterranean region and South-East Asia.
  • Liver inflammation: Hepatitis (liver inflammation) may also occur. This is usually mild and does not cause symptoms, so regular blood tests are important. The problem resolves if the treatment is stopped.
  • Severe rash and fever: In very rare cases, sulfasalazine is associated with a severe skin rash and fever. If this occurs, the medicine should be stopped, and your doctor contacted immediately.
  • Other rare effects include reversible lung inflammation and pins and needles in the hands and feet.


What precautions are necessary?

Blood tests

  • Since sulfasalazine may affect the blood cells and liver, you must have regular blood tests during your treatment. This is important, as you may not get symptoms with these problems.
  • Blood tests should be done two weeks after commencing this medicine and then every month.
  • Blood tests are particularly important during the first few months of treatment and when sulfasalazine is taken with methotrexate and/or leflunomide.
  • As well as monitoring for side effects, blood tests help to monitor your condition to determine if the treatment is effective.
  • The blood count and liver function tests are required every 2 to 3 weeks for the first 3 months then 3 to 6 monthly after that.
  • Your general practitioner (GP) will be informed about the monitoring schedule. It is important to see your GP if you have been asked to do so as they have an important role to play in monitoring your condition.

Precautions with other diseases or conditions

  • You should not take sulfasalazine if you have sensitivity to aspirin compounds or sulphur containing medicines such as sulphur antibiotics (e.g. Bactrim or Septrim).
  • If you have blood, kidney or liver disorders your doctor will discuss your medical history to decide whether this treatment is suitable for you.

Use with other medicines

  • Sulfasalazine can interact with other medicines. You should tell all of your doctors about all medicines you are taking or plan to take. This includes over the counter or herbal/naturopathic medicines.
  • Sulfasalazine may interfere with warfarin (Coumadin, Marevan) a blood thinning medicine. Dose adjustments may be needed if these two medicines are taken together.
  • Sulfasalazine may interfere with digoxin, so dose adjustments may be needed if these two medicines are taken together.
  • Antacids can slow the absorption of sulfasalazine. Do not take antacids within 2 hours of taking sulfasalazine.
  • Sulfasalazine is often used with other DMARDs to treat rheumatoid arthritis. Combination therapy is now standard practice. There are usually no more side effects than with a single DMARD.
  • Sulfasalazine can increase the risk for liver injury if given with isoniazid, a medicine used for tuberculosis.
  • Most vaccines can be given safely with sulfasalazine.
  • Talk with your rheumatologist before receiving any vaccines. More information on vaccinations including the COVID-19 vaccine can be found here.

Use with alcohol

  • Because sulfasalazine can affect your liver, you should avoid heavy alcohol use while taking it.
  • It is not known precisely what level of drinking is safe when on sulfasalazine.
  • However there is general agreement that 1 to 2 standard drinks taken once or twice a week is unlikely to cause a problem.
  • Drinking more than 4 standard drinks on one occasion, even if infrequently, is strongly discouraged.

Pregnancy, breastfeeding and fertility

  • Sulfasalazine has been used safely in pregnancy and breastfeeding. Should you wish to become pregnant or you intend to breastfeed, you should discuss this with your rheumatologist.
  • In males, sulfasalazine can cause a lowered sperm count which may result in temporary infertility. This is reversible on stopping sulfasalazine. Discuss with your rheumatologist before attempting to start a family.
  • More detailed information is available here.


How to store sulfasalazine

  • Store sulfasalazine in a cool, dry place, away from direct heat and light (e.g. not in the bathroom).
  • Keep all medicines out of reach of children.


Important things to remember

  • While taking sulfasalazine you must see your rheumatologist regularly to make sure the treatment is working and to minimise any possible side effects.
  • If you are concerned about any side effects you should contact your rheumatologist as soon as possible.
  • It is important to have regular blood tests as directed by your doctor.


This information has been produced by the Australian Rheumatology Association (ARA) to help you understand the medicine that has been prescribed for you. Please read it carefully and discuss it with your doctor. The information in this sheet has been obtained from various sources and has been reviewed by the ARA. It is intended as an educational aid and does not cover all possible uses, actions, precautions, side effects, or interactions of the medicines mentioned. This information is not intended as medical advice for individual problems nor for making an individual assessment of the risks and benefits of taking a particular medicine. It can be reproduced in its entirety but cannot be altered without permission from the ARA. The NHMRC publication: How to present the evidence for consumers: preparation of consumer publications (2000) was used as a guide in developing this publication.

Last reviewed October 2021.