Quick answer: Sulfasalazine is a disease-modifying anti-rheumatic drug (DMARD) used for rheumatoid arthritis, psoriatic arthritis and some other inflammatory conditions. It calms the immune system slowly, so it can take around two to three months to make a real difference. You will need regular blood tests, especially at first. Common side effects include feeling sick, headaches and orange-coloured urine. Always follow your rheumatology team's dosing plan.
What sulfasalazine is and how it works
Sulfasalazine has been used for many decades. It is a combination of a sulfa antibiotic-like part and an aspirin-like part, and it works by damping down the overactive immune response that causes inflammation in the joints. It does not work like a painkiller. Instead it slowly reduces inflammation, which over time eases pain, stiffness and swelling and helps protect joints from damage.
In the UK it is most often used for:
- Rheumatoid arthritis, on its own or combined with other DMARDs such as methotrexate or hydroxychloroquine.
- Psoriatic arthritis, particularly when joints in the arms and legs are affected.
- Some types of spondyloarthritis with peripheral joint involvement, and inflammatory bowel disease.
It is one of several conventional DMARDs. Our guide to DMARDs versus biologics explains where it fits alongside other treatments.
How you take it
Sulfasalazine comes as tablets, usually the enteric-coated (gastro-resistant) type, which are gentler on the stomach. Your team will usually start you on a low dose and increase it step by step over the first few weeks, which helps your body get used to it. The exact plan varies, so follow the schedule your rheumatology team or pharmacist gives you and do not change the dose yourself.
Tips that help many people:
- Take the tablets with or just after food and a glass of water.
- Swallow enteric-coated tablets whole. Do not crush or chew them.
- Set a phone reminder or use a pill organiser.
- If you miss a dose, check the leaflet or ask your pharmacist. Do not take a double dose to make up.
How long does it take to work?
Sulfasalazine works slowly. Some people notice a change after a few weeks, but it often takes around two to three months to see the full benefit. During that time your team may suggest other ways to control symptoms, such as anti-inflammatory painkillers or a short course of steroids. It is worth sticking with it through this early period unless you have side effects your team is concerned about.
Blood tests and monitoring
Sulfasalazine can occasionally affect blood cells and the liver, so you will have regular blood tests. These are usually more frequent in the first few months, and less often once you have been on a stable dose for a while. Monitoring schedules are set by your team and local shared-care arrangements. The tests usually include:
- A full blood count, to check white cells, red cells and platelets.
- Liver function tests.
- Kidney function tests.
Many people keep a monitoring booklet or use an app to track their results. If you struggle to get to appointments, our guide to getting to blood tests has practical ideas.
Common side effects
Many people take sulfasalazine with few or no problems. Side effects are most likely in the first few months, and some settle as your body adjusts. Common ones include:
- Feeling sick, loss of appetite, indigestion or tummy pain. Taking tablets with food and building up the dose slowly usually helps.
- Headaches and dizziness.
- A rash or itchy skin.
- Orange or yellow colouring of urine, sweat and tears. This is harmless, but it can stain soft contact lenses, so you may want to switch to glasses or daily lenses.
- A temporary drop in sperm count in men, which recovers after stopping. Mention this if you are planning a family.
The NHS medicines pages and the patient leaflet in your pack list other, less common side effects.
When to contact your team urgently
Rarely, sulfasalazine can affect the bone marrow, liver or skin in serious ways. Contact your GP or rheumatology advice line the same day, or call NHS 111, if you notice:
- A sore throat, fever, chills or mouth ulcers.
- Unexplained bruising or bleeding.
- Yellowing of the skin or whites of the eyes.
- A widespread rash, blistering or peeling skin, especially with a fever.
- Unusual breathlessness or a persistent cough.
Call 999 if you have signs of a severe allergic reaction, such as swelling of the lips, tongue or throat or difficulty breathing.
Alcohol, other medicines and vaccines
- Alcohol: there is no specific interaction, but it is sensible to stay within UK low-risk drinking guidelines. See our guide to arthritis and alcohol.
- Allergies: tell your team if you are allergic to sulfa antibiotics (sulfonamides) or aspirin, as sulfasalazine may not be suitable.
- Other medicines: always tell pharmacists and other clinicians you take sulfasalazine, including before buying remedies or supplements. Our guide to medicine and supplement interactions can help.
- Vaccines: sulfasalazine on its own is not usually strongly immune-suppressing, but check with your team about vaccines, particularly if you take it with other DMARDs. See our vaccines guide.
Pregnancy and breastfeeding
Sulfasalazine is one of the arthritis medicines that can often be continued during pregnancy and breastfeeding, and extra folic acid is usually recommended. Every situation is different, so talk to your rheumatology team before trying for a baby, and let them know as soon as possible if you become pregnant. Our guide to arthritis and pregnancy has more.
If it is not working, or you need to stop
Not every medicine suits every person. If sulfasalazine has not helped enough after a fair trial, or side effects are a problem, your team may adjust the dose, add another medicine or switch to a different treatment, such as another DMARD or a biologic. Stopping should be planned with your team, because inflammation can return quickly without treatment. Our guide to stopping arthritis medicines safely explains why. If you are worried about taking sulfasalazine long term, raise it at your next review or call your advice line. Your concerns matter, and there is usually more than one option.
Frequently asked questions
How long does sulfasalazine take to work?
Many people notice some improvement within a few weeks, but it often takes around two to three months to reach its full effect.
Why has my urine turned orange on sulfasalazine?
Sulfasalazine is a yellow-orange compound and can colour urine, sweat and tears. This is harmless, but it can stain soft contact lenses and some clothing.
Can I drink alcohol while taking sulfasalazine?
There is no specific interaction, but keeping within UK low-risk drinking guidelines is sensible. If you also take methotrexate or leflunomide, follow the alcohol advice for those medicines.
Do I need blood tests on sulfasalazine?
Yes. Regular blood counts and liver and kidney tests are needed, more often at first. Your team or GP will explain your schedule.
Can I take sulfasalazine with methotrexate?
Yes, they are often combined, sometimes with hydroxychloroquine as well. Your team will decide whether a combination suits you.
What should I do if I get a sore throat or fever?
Contact your GP or rheumatology advice line the same day, or call NHS 111. You may need a blood test to check your white cell count.
Sources and further reading
This guide is for general education and is not a substitute for personal medical advice. Everyone's situation is different, so always follow the advice of your own GP, pharmacist or rheumatology team. If you feel very unwell, call 999 or go to A&E. For urgent advice, contact NHS 111.