Sulfasalazine for ulcerative colitis and Crohn's disease

What is sulfasalazine for Crohn’s disease and ulcerative colitis?

Sulfasalazine (also known as sulphasalazine) belongs to a group of medicines called aminosalicylates (5-ASAs), which are medicines commonly used to treat ulcerative colitis and Crohn’s disease. 5-ASA medicines are chemically related to aspirin, and work by reducing inflammation in your gut. 

5-ASAs are not immunosuppressants.

There are several other types of 5-ASA medicines regularly used to treat inflammatory bowel disease (IBD) including:

How does sulfasalazine work for IBD?

It is not known exactly how sulfasalazine (and all types of 5-ASA medicine) works in treating IBD, but it is thought to slow down your body's production of prostaglandins, chemicals that have a key role in causing inflammation. 

Each type of 5-ASA is formulated slightly differently, and works best in certain parts of your gut. Sulfasalazine treats your terminal ileum (the end of your small intestine) and your colon (large bowel).

Sulfasalazine v mesalazine

You might be wondering what the difference is between sulfasalazine and mesalazine, another commonly prescribed 5-ASA, is.

Sulfasalazine was the first widely prescribed 5-ASA medicine, and it contains a sulfonamide - an antibacterial medicine. Some people cannot tolerate the sulfonamides in sulfasalazine. Quite often, these people can take mesalazine instead, as mesalazine doesn’t contain any sulfonamides. Mesalazine is also available in different formulations which control its release to target specific areas of your bowels1.


Why have I been prescribed sulfasalazine for inflammatory bowel disease?

Sulfasalazine and ulcerative colitis

Sulfasalazine is a common first treatment for mild to moderate flare ups of ulcerative colitis, and around seven in 10 people find it works well for them.

Sulfasalazine is also used as a maintenance treatment for ulcerative colitis, to keep you well once your UC is in remission.

Sulfasalazine and Crohn’s disease

Sulfasalazine is occasionally used as a first treatment option in mild Crohn’s disease. It can also be used to help manage Crohn’s disease symptoms post surgery.

There is little evidence to support the use of sulfasalazine to treat or maintain remission in moderate to severe Crohn’s disease. (2) 

What are the different brands of sulfasalazine for IBD?

Sulfasalazine, sometimes called sulphasalazine, is often just referred to under its name - sulfasalazine (known as the generic name). However, there are also a couple of brands of sulfasalazine used in ulcerative colitis and Crohn’s disease which you may be prescribed. These include:

  • Salazopyrin
  • Azulfidine

How do I take sulfasalazine to treat IBD?

Your doctor will give you detailed information about the dosage and method of application of sulfasalazine for your IBD. This will depend on the severity and location of the inflammation in your gut. You can also read the patient information leaflet included in every medicine packet.

You will usually be prescribed a higher dose of sulfasalazine to treat a flare up, then a lower dose to maintain remission (keep you well) once your inflammation and symptoms are under control.

Sulfasalazine is available as:

  • Tablets (500mg)
  • Enteric coated tablets (500mg)
  • Liquid suspension (500mg/5ml)
  • Suppositories
  • Liquid enemas

Tablets can be swallowed with water. Tablets with an enteric coating (this is a special coating that allows the medicine to be released in the right part of your gut) must not be crushed or chewed, or taken at the same time as indigestion remedies, as this will affect how they work. 

If you feel nauseous taking sulfasalazine, it can help to split your dose up throughout the day. Ask your IBD team about this.

Sulfasalazine suppositories and enemas are used to treat the lower part of your colon and your rectum. Sulfasalazine suppositories are small bullet shaped capsules inserted into your anus using a finger, where they dissolve. Liquid enemas come in a container with a specially designed applicator, which you insert into your anus and squeeze the liquid inside your body. 

People are often worried about taking rectal medicines at first. To help make it easier you could:

  • Take them at bedtime. You are less likely to be rushed and may be more relaxed
  • Go to the toilet before you take them
  • Lay down to take them and stay lying down for a few minutes afterwards as this can make it easier for you to hold the medicine in
  • Try to be gentle on yourself - don’t worry if it doesn’t go quite as well as you’d hoped first time, you will soon get used to it

If you forget to take a dose of your sulfasalazine at the right time, take it as soon as you remember, then carry on as normal. If it is almost time to take your next dose, skip the missed dose then carry on as normal.  

How long will sulfasalazine take to work?

It can take several weeks for sulphasalazine to start working for you. You should keep taking your prescribed dose even when you feel better.

Sulfasalazine is also a maintenance treatment which, if it works for you, you will probably take long term, for years or even indefinitely, in order to keep your disease under control and reduce the risk of flare ups.

What do I need to know before taking sulfasalazine?

Before you start taking sulfasalazine, you will have a blood test to check your kidney function. Sulfasalazine is cleared from your body through your kidneys. If your kidneys aren’t working well, they won’t be able to get rid of the medicine. This will increase your risk of side effects

You shouldn’t take sulfasalazine if you are sensitive to sulfonamides or salicylates.

It is generally considered safe to take sulfasalazine whilst you are pregnant or breastfeeding. However, sulfasalazine can cause folate deficiency so you may need to take a daily folic acid supplement. Speak to your IBD team if you are hoping to become pregnant. 

Sulfasalazine can affect male fertility by reducing sperm count. This usually resolves within a couple of months of stopping treatment. If you are trying for a baby, you may need to be switched to a different type of 5-ASA medicine.

You can drink alcohol in moderation whilst taking sulfasalazine, although it can sometimes aggravate nausea.

How will I be monitored while I’m taking sulfasalazine for ulcerative colitis or Crohn’s disease?

You will usually have regular blood tests to monitor your kidney and liver function, your blood count, and to check for any unwanted side effects. These tests are likely to be every three months for the first year, then once every six months or every year after that. 

What side effects could I get while taking sulfasalazine?

It is less likely you will have side effects with sulfasalazine than with other IBD medicines, and around eight in 10 people don’t have any at all. If you experience any of these side effects, contact your IBD team straight away.

Common side effects include:

  • Headaches (this is often the reason why patients who stop taking sulfasalazine can’t continue)
  • Indigestion
  • Nausea
  • Diarrhoea
  • A metallic taste in the mouth
  • Tiredness
  • A mild allergic reaction, including a rash, itchiness or fever
  • Nervousness
  • Sensitivity to sunlight
  • Reduction in sperm count (usually temporary)
  • Reduction of absorption of folic acid

Less common side effects include:

  • Inflammation of the liver
  • Lung inflammation (pneumonitis)
  • Inflammation of the kidney
  • Pancreatitis
  • A skin reaction called Stevens-Johnson syndrome
  • A change in blood cell production in the bone marrow, causing bleeding, bruising, sore throat and fever

Sulfasalazine is yellow/orange coloured, and you may notice your urine, tears and sweat develops a yellow tinge. This is nothing to worry about, but it can sometimes stain clothing and contact lenses.

Can I take other medicines with sulfasalazine?

Sulfasalazine is often prescribed alongside other medicines for your IBD, such as steroids or azathioprine. This is called combination therapy and is used to help treatment work more quickly or more effectively.

Folic acid is often prescribed alongside sulfasalazine. 

Most other medicines, including over-the-counter, herbal and complementary medicines can be taken alongside sulfasalazine, but you should always check with your IBD team or pharmacist first. 

It is considered safe to have vaccinations while taking sulfasalazine, although you should check with your IBD team beforehand, especially if you are taking other medicines for IBD.

Sulfasalazine and COVID-19

Having inflammatory bowel disease does not increase your risk of contracting COVID-19. However, if you are having a flare, have underlying health conditions, or if you are taking certain medicines, you can be at increased risk of developing complications if you contract the virus.

Sulfasalazine does not increase your risk of severe symptoms or complications if you contract COVID-19. You should continue to take your sulfasalazine as normal. You can contact your IBD team if you have any questions or concerns.

Like everyone else, you should take precautions to avoid infection through good personal hygiene and avoiding unnecessary close contact with other people, especially if they are unwell.

Funding to help in the production of this article was received from PredictSURE IBD, however they had no input into its content.

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