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Sulfasalazine - Brand name: Salazopyrin

On this page

  1. About sulfasalazine
  2. Key facts
  3. Who can and cannot take sulfasalazine
  4. How and when to take sulfasalazine
  5. Side effects
  6. How to cope with side effects of sulfasalazine
  7. Pregnancy and breastfeeding
  8. Cautions with other medicines
  9. Common questions about sulfasalazine

1. About sulfasalazine

Sulfasalazine is used to treat ulcerative colitis and Crohn's disease, and other types of inflammatory bowel disease.

It can also be used to treat rheumatoid arthritis.

It belongs to a group of medicines called aminosalicylates. These medicines help to reduce redness and swelling (inflammation) and can help with healing.

Some people take sulfasalazine together with steroids.

Sulfasalazine is available on prescription only.

It comes as tablets or a liquid that your swallow. It also comes as suppositories (a medicine that you push into your bottom).

2. Key facts

  • You'll need blood tests and liver and kidney tests before you start treatment with sulfasalazine, and then regular monitoring tests.
  • The most common side effects of sulfasalazine are indigestion and feeling sick.
  • Drink plenty of fluids when taking sulfasalazine to help prevent possible kidney problems.
  • Once your symptoms are under control, you can usually go onto a lower dose, called a maintenance dose.
  • This medicine is a yellow or orange colour. It can make your pee turn orange. It can also stain some types of soft contact lenses, so you may need to switch to a different type.

3. Who can and cannot take sulfasalazine

Adults and children aged 2 years and older can take sulfasalazine.

Sulfasalazine is not suitable for some people. To make sure it's safe for you, tell your doctor before starting the medicine if you:

  • have ever had an allergic reaction to sulfasalazine, aspirin, or any other salicylates such as methyl salicylate or choline salicylate
  • have ever had an allergic reaction to any other medicine
  • have a rare blood condition called porphyria
  • have any problems with your kidneys or liver
  • are pregnant, trying to get pregnant or breastfeeding

4. How and when to take sulfasalazine

Always follow your doctor's advice and the instructions that come with your medicine.

Dosage and strength

The tablets and suppositories contain 500mg of sulfasalazine. The liquid contains 250mg per 5ml.

Doses will vary. Your dose and how often you take it depends on why you need sulfasalazine and how severe your symptoms are.

For inflammatory bowel disease the usual dose is either:

  • 2 to 4 tablets or 20ml to 40ml of liquid, 4 times a day
  • 1 to 2 suppositories, twice a day

For rheumatoid arthritis, when you start treatment you'll usually take one 500mg tablet a day. This will increase by 1 tablet a day each week until you reach a dose of 1 tablet 4 times a day, or 2 tablets 3 times a day, depending on how you respond to it.

Children's doses are often lower. The doctor will use your child's weight to calculate the right dose for them.

How to take sulfasalazine tablets

Swallow the tablets whole, with a drink of water. Do not break, chew or crush them. This is because some tablets have a special coating to protect the medicine from the acids in your stomach.

You can take sulfasalazine tablets with or without food.

Try to space the doses evenly throughout the day and night, with a gap of no more than 8 hours between your bedtime and morning dose.

Drink plenty of fluids when taking this medicine to help prevent possible kidney problems.

How to take sulfasalazine liquid

Take the liquid with food. You'll usually take the same amount 4 times a day.

How to use sulfasalazine suppositories

Sulfasalazine suppositories are used to treat inflammatory bowel disease.

You will generally use the suppositories twice a day, in the morning and at bedtime. Use them after you do a poo.

  1. Wash your hands before and after using the suppository. Also clean around your bottom (anus) with mild soap and water, rinse and pat dry.
  2. Unwrap the suppository.
  3. Gently push the suppository into your anus with the pointed end first. It needs to go in about 3 centimetres (1 inch).
  4. Sit or lie still for about 15 minutes. The suppository will melt inside your bottom. This is normal.
  5. Try not to empty your bowels for at least an hour after inserting the suppository so it will work better.

Will my dose go up or down?

Once your symptoms start to get better, your doctor may reduce your dose to a maintenance dose. This is a lower dose of sulfasalazine that helps keep your symptoms under control.

If your symptoms flare up again, your doctor may want to put your dose back up.

What if I forget to take it?

If you miss a dose of sulfasalazine, take it as soon as you remember, unless it's nearly time for your next dose. In this case, skip the missed dose and take your next one at the usual time.

Do not take a double dose to make up for a forgotten dose.

If you often forget doses, it may help to set an alarm to remind you. You could also ask your pharmacist for advice on other ways to help you remember your medicine.

What if I take too much?

Taking too much sulfasalazine is unlikely to cause you any problems.

However, speak to your doctor or a pharmacist if you take more than double your usual dose and you feel unwell. They may need to monitor you for side effects.

5. Side effects

Like all medicines, sulfasalazine can cause side effects, but many people have no side effects or only minor ones.

You're more likely to have side effects if you're taking a high dose of sulfasalazine. Sulfasalazine can turn your pee orange. This is harmless and nothing to worry about.

It's unusual, but sulfasalazine can also stain certain types of soft contact lenses. Single-use daily contact lenses are not affected.

Common side effects

Sulfasalazine side effects can vary depending on whether you are taking it as a tablet, suppository or liquid.

Keep taking the medicine, but tell your doctor if these side effects bother you or do not go away.

Common side effects which may affect more than 1 in 100 people include:

  • indigestion and heartburn
  • feeling sick (nausea)
  • diarrhoea
  • being sick (vomiting)
  • stomach (abdominal) pain
  • feeling dizzy
  • headache, joint aches and pains
  • itching or mild rash
  • cough, sore mouth or changes in the way things taste (a metallic taste and changes in the way sweet things taste)
  • difficulty sleeping
  • ringing in your ears (tinnitus)

Serious side effects

Serious side effects are very rare, affecting less than 1 in 10,000 people.

Call a doctor straight away if you get:

  • a high temperature, chills, a sore throat, ear or sinus pain, a cough, pain when peeing, mouth sores, a wound that will not heal or feeling generally ill – these can be signs of an infection
  • a high temperature and sore throat, skin becoming paler than usual, unusual bruising or bleeding, or unusual tiredness or weakness – these can be signs of a blood problem
  • change in the amount of pee you produce or pain when peeing – these can be signs of kidney problems
  • chest pain, an increase in heartbeat or feeling much more tired than usual – these can be signs of heart problems
  • yellowing of the eyes or skin (this may be less obvious on brown or black skin), dark pee, stomach pain, a high temperature, feeling tired or feeling sick – these can be signs of a serious liver problem
  • back or stomach pain, a high temperature, feeling sick (nausea) and being sick (vomiting) – these can be signs of a problem with your pancreas

Serious allergic reaction

In rare cases, it's possible to have a serious allergic reaction (anaphylaxis) to sulfasalazine.

Immediate action required: Call 999 now if:
  • your lips, mouth, throat or tongue suddenly become swollen
  • you're breathing very fast or struggling to breathe (you may become very wheezy or feel like you're choking or gasping for air)
  • your throat feels tight or you're struggling to swallow
  • your skin, tongue or lips turn blue, grey or pale (if you have black or brown skin, this may be easier to see on the palms of your hands or soles of your feet)
  • you suddenly become very confused, drowsy or dizzy
  • someone faints and cannot be woken up
  • a child is limp, floppy or not responding like they normally do (their head may fall to the side, backwards or forwards, or they may find it difficult to lift their head or focus on your face)

You or the person who's unwell may also have a rash that's swollen, raised, itchy, blistered or peeling.

These can be signs of a serious allergic reaction and may need immediate treatment in hospital.

These are not all the side effects of sulfasalazine. For a full list see the leaflet inside your medicines packet.


You can report any suspected side effect using the Yellow Card safety scheme.

Visit Yellow Card for further information.

6. How to cope with side effects of sulfasalazine

What to do about:

  • indigestion and heartburn – it might help to take your sulfasalazine a few minutes before or after a meal. If you need something to ease the discomfort, try taking an antacid.
  • feeling sick – stick to simple meals and do not eat rich or spicy food. It might help to take your sulfasalazine after you've eaten.
  • diarrhoea – drink lots of fluids, such as water or squash, to avoid dehydration. Signs of dehydration include peeing less than usual or having dark strong smelling pee. Do not take any other medicines to treat diarrhoea without speaking to a pharmacist or doctor.
  • being sick – stick to simple meals and do not eat rich or spicy food. It might help to take your sulfasalazine after you've eaten. If you're being sick, try small frequent sips of water to avoid dehydration. Signs of dehydration include peeing less than usual or having dark, strong smelling pee.
  • stomach (abdominal) pain – it can help to eat and drink slowly and have smaller and more frequent meals. Putting a heat pad or covered hot water bottle on your stomach may also help.
  • feeling dizzy – sit down for a while until the feeling passes. Do not drive, cycle or use tools or machinery until you feel better.
  • headache, joint aches and pains – drink plenty of water and ask your pharmacist to recommend a suitable painkiller. If the headache or pains continue or are severe, and taking a painkiller does not help, let your doctor know.
  • itching or mild rash – it may help to take an antihistamine which you can buy from a pharmacy. Check with the pharmacist to see what type is suitable for you.
  • cough, sore mouth or changes in the way things taste (a metallic taste and changes in sweet tastes) – try chewing sugar-free gum. If you're coughing try having frequent sips of water or other unsweetened drinks.
  • difficulty sleeping – avoid having a big meal, smoking, or drinking alcohol, tea or coffee in the evening. Try not to watch television or use your mobile phone before going to bed. Instead, try to relax for an hour before bedtime.
  • ringing in your ears (tinnitus) – speak to your doctor if this lasts longer than 2 days.

7. Pregnancy and breastfeeding

Sulfasalazine and pregnancy

There are no concerns that taking sulfasalazine in pregnancy can harm your baby.

Sulfasalazine can affect your folic acid levels. To help with this, take high dose folic acid (5mg a day), particularly in the 3 months before you start trying to get pregnant and during the first 12 weeks of pregnancy.

You can continue taking folic acid throughout your pregnancy.

Talk to your doctor or midwife if you're trying to get pregnant, or as soon as you become pregnant, so that high dose folic acid can be prescribed.

Sulfasalazine and breastfeeding

You may be able to take sulfasalazine while breastfeeding. Talk to your doctor, a pharmacist or your health visitor if you want to breastfeed.

Small amounts of sulfasalazine pass into breast milk and are unlikely to cause any side effects in your baby, although there have been some rare cases of diarrhoea.

Tell your midwife, health visitor or doctor as soon as possible if you notice your baby is not feeding as well as usual, has diarrhoea, or if you have any other concerns about your baby.

Non-urgent advice: Tell your doctor if you're:

  • trying to get pregnant
  • pregnant
  • breastfeeding

For more information about how sulfasalazine can affect you and your baby during pregnancy, read this leaflet on the Best Use of Medicines in Pregnancy (BUMPs) website.

8. Cautions with other medicines

There are some medicines that can affect the way sulfasalazine works.

Tell your doctor or pharmacist if you're taking:

  • digoxin, a medicine for heart problems
  • medicines for high blood sugar or diabetes, such as metformin or glibenclamide
  • methenamine, a specific antibiotic sometimes used for treating urinary tract infections (UTIs)
  • folic acid, often taken in first 12 weeks of pregnancy, as it may be less well absorbed so you may need to take a higher dose than usual
  • azathioprine or mercaptopurine, taken for rheumatoid arthritis or to prevent organ rejection after a transplant
  • methotrexate which is usually used to treat rheumatoid arthritis

Mixing sulfasalazine with herbal remedies or supplements

There's very little information about taking herbal remedies and supplements with sulfasalazine. They are not tested in the same way as other medicines.

Important: Medicine safety

Tell your doctor or pharmacist if you're taking any other medicines, including herbal medicines, vitamins or supplements.

9. Common questions about sulfasalazine

How does sulfasalazine work?

Sulfasalazine works by reducing swelling (inflammation). This helps reduce the symptoms of inflammatory conditions, such as inflammatory bowel disease and rheumatoid arthritis.

It's not known exactly how sulfasalazine does this. It's thought to stop your body producing chemicals that cause redness and swelling in the gut (in Crohn's disease and ulcerative colitis) and in the joints (in rheumatoid arthritis).

Sulfasalazine has a similar effect to immunosuppressants. It can reduce the numbers of white cells in your blood, reducing your body's ability to fight infection.

How long does it take to work?

Sulfasalazine does not work straight away.

If you're taking sulfasalazine for inflammatory bowel disease, you must continue taking it even if you feel well in order to remain well.

If you have rheumatoid arthritis it may take 1 to 3 months before you notice your symptoms get better.

It depends on how high your dose is and how severe your symptoms are.

How long will I take it for?

Sulfasalazine can be used at a higher dose for a short time to treat flare-ups.

You can also take it long term to keep inflammation under control and prevent symptoms from flaring up again. How long you use it for will depend on your condition and how severe it is.

Do not stop using sulfasalazine unless your doctor tells you to.

Is it safe to take for a long time?

Sulfasalazine can be taken long term. However, your doctor will want to check how your kidneys are working before and during treatment. In rare cases sulfasalazine can cause kidney problems.

These checks usually happen once every 3 months for the first year. You will usually need a check once a year after that or as often as your doctor recommends.

Can I stop taking sulfasalazine?

If you are thinking of stopping sulfasalazine, discuss this with your doctor first as your symptoms may return.

If side effects are bothering you and you want to stop taking sulfasalazine, talk to your doctor first. They may want to review your treatment.

Do not stop using sulfasalazine unless your doctor tells you to.

Can I take sulfasalazine before surgery or dental treatment?

If you're due to have any surgery or dental treatment, tell your doctor or dentist before your treatment that you are taking sulfasalazine.

They will tell you if you need to stop taking it.

Can I take painkillers with sulfasalazine?

You can take paracetamol with sulfasalazine.

However, it's best to avoid non-steroidal anti-inflammatory drugs (NSAIDs) such as aspirin or ibuprofen. Like sulfasalazine, NSAIDs can cause problems with the way your kidneys work.

Sulfasalazine is used to treat ulcerative colitis, Crohn's disease and other inflammatory bowel diseases. NSAIDs can irritate the gut and so increase the risk of ulceration and bleeding.

Ask a pharmacist or doctor for advice if paracetamol is not working for you.

Can I drink alcohol with sulfasalazine?

You can drink alcohol while taking sulfasalazine.

However, alcohol can irritate your gut so may make symptoms worse if you have inflammatory bowel disease.

Is there any food or drink I need to avoid?

You can usually eat and drink normally while taking sulfasalazine.

If you have indigestion or feel sick, it's best to stick to simple meals, and avoid alcohol and spicy foods.

For inflammatory bowel disease, your doctor may advise you make some changes to your diet as part of your treatment. This can include following a special diet or adding a nutritional supplement.

Will sulfasalazine affect my fertility?

There's no evidence to suggest that taking sulfasalazine will reduce fertility in women. Women should take high dose folic acid (5mg a day) if trying to get pregnant.

There are some reports of sulfasalazine reducing sperm count in men. This usually gets better 2 to 3 months after stopping treatment. If you are a man, and are having difficulty in conceiving after 12 months of trying, then you may wish to discuss stopping sulfasalazine with your doctor.

Will sulfasalazine affect my contraception?

Sulfasalazine does not affect any type of contraception, including the combined pill and emergency contraception.

However, if using sulfasalazine makes you vomit or have severe diarrhoea for more than 24 hours, your contraceptive pills may not protect you from pregnancy. Look on the pill packet to find out what to do.

Read more about what to do if you're taking the pill and you're being sick or have diarrhoea.

Can I drive or ride a bike?

Feeling dizzy is a common side effect of sulfasalazine. If you feel dizzy or drowsy, do not drive or cycle, or use tools or machinery, until you feel better.

Are there other treatments for Crohn's disease and ulcerative colitis?

Other medicines used to treat Crohn's disease and ulcerative colitis include:

Read more about the different treatments for Crohn's disease.

Read more about the different treatments for ulcerative colitis.

Are there other treatments for rheumatoid arthritis?

Other medicines used to treat rheumatoid arthritis include:

  • disease-modifying anti-rheumatic drugs such as methotrexate (an immunosuppressant) and mesalazine
  • a short course of steroids
  • biological medicines, such as adalimumab

Read more about the different treatments for rheumatoid arthritis.