Aminosalicylates (5-ASAS) for ulcerative colitis & Crohn's disease

What are aminosalicylates for ulcerative colitis and Crohn’s disease?

Aminosalicylates, also known as 5-ASAs, are a group of medicines commonly used to treat ulcerative colitis and Crohn’s disease. They are often the first medicines prescribed to people who are newly diagnosed with ulcerative colitis, and sometimes mild Crohn’s disease. 5-ASAs have been used in inflammatory bowel disease (IBD) for many years, and are considered a safe and effective treatment.

There are several types of 5-ASA medicines including:

  • Sulfasalazine (sulphasalazine) - brand names include Salazopyrin, Sulazine and Azulfadine
  • Mesalazine (mesalamine) - brand names include Asacol, Octasa, Pentasa, Ipocol, Salofalk and Mezavant
  • Olsalazine - brand names include Dipentum
  • Balsalazide - brand names include Colazal and Giazo

You can find more information about some of these 5-ASA medicines in the articles below...

How do 5-ASAs work in IBD?

Aminosalicylate medicines contain 5-aminosalicylic acid, and are chemically related to aspirin. 

During a flare up of ulcerative colitis or Crohn’s disease, parts of your gut become inflamed, and 5-ASAs can help to reduce this inflammation. It is not known exactly how 5-ASA medicines work, but they are 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 targets slightly different parts of your gut. You may be prescribed a particular type, brand or route of administration (how you take your medicine) depending on the location of your disease.

Why have I been prescribed aminosalicylates for my inflammatory bowel disease?

Ulcerative colitis

5-ASAs are a common first treatment for mild to moderate flare ups of ulcerative colitis. They are a maintenance treatment for ulcerative colitis, which means they are used to maintain remission. Remission is where you no longer have any active disease.

Crohn’s disease

5-ASAs are sometimes used as a first treatment option in mild Crohn’s disease. Some 5-ASAs can also be used to help manage Crohn’s disease symptoms post surgery.

5-ASAs are not usually used to treat or maintain remission in moderate to severe Crohn’s disease.

With other medications

5-ASAs are often used in conjunction with other medicines to control inflammatory bowel disease. This is called combination therapy.

How do I take 5-ASAs for IBD?

Your IBD team will give you detailed information about your dosage and how you take your 5-ASA medicine. It will depend on the severity and location of your disease. You can also read the patient information leaflet included in every medicine packet.

Tablets, capsules and liquid suspensions

Oral 5-ASAs are often prescribed in two or three doses throughout the day, however you may be able to take them as a single dose. Discuss this with your IBD team if you think it would be easier for you. 

If you are prescribed tablets with an enteric coating (this is a special coating that allows the medicine to be released in the right part of your bowel) then they must not be crushed or chewed, or taken at the same time as indigestion remedies, as this will affect how they work. 


Some 5-ASAs come as granules. You put them onto your tongue and swallow them with plenty of water, without chewing. 


Suppositories, enemas and rectal foams are used to treat inflammation in the lower part of your colon and your rectum. 

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. 

Rectal foams come in an aerosol can with special applicators. You insert these into your anus and release the foam into your rectum and lower part of your colon.

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

How long will 5-ASAs take to work for inflammatory bowel disease?

It can take a few weeks for 5-ASAs to start working. You should keep taking your prescribed dose even if you feel better. 5-ASAs are maintenance treatments which, if they work for you, you will probably take for years or even indefinitely, in order to keep your disease under control and reduce the risk of flare ups.

Side effects of 5-ASAs for ulcerative colitis or Crohn’s disease

It is less likely you will have side effects when taking 5-ASAs than with other IBD medicines. 

Common side effects include:

  • Headaches
  • Indigestion
  • Nausea
  • Diarrhoea
  • Tiredness
  • A mild allergic reaction, including a rash, itchiness or fever

Sulfasalazine only:

  • 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 change in blood cell production in the bone marrow, causing bleeding, bruising, sore throat and fever

Sulfasalazine only:

  • A skin condition called Stevens-Johnson syndrome

You should contact your IBD team for advice if you are experiencing any side effects that are difficult to manage. Do not stop taking your 5-ASA medicines without speaking to your IBD team.

What do I need to know before taking 5-ASAs for IBD?

Before taking 5-ASAs you will have a blood test to check your kidney function. 5-ASAs are 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 as efficiently. This will increase your risk of side effects.

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 after three months, then once a year after that. 

You can drink alcohol in moderation whilst taking 5-ASAs.

It is generally considered safe to take 5-ASAs whilst you are pregnant or breastfeeding. 

Sulfasalazine only:

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.

Can I take other medicines with 5-ASAs?

5-ASAs are 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.

Most other medicines can be taken alongside 5-ASAs, including over-the-counter, herbal and complementary medicines, but you should always check with your IBD team or pharmacist before taking them. 

It is considered safe to have vaccinations while taking 5-ASAs, although you should check with your IBD team beforehand, especially if you are taking other medicines for IBD.

Folic acid is often prescribed alongside sulfasalazine.

5-ASAs 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.

5-ASAs do not increase your risk of severe symptoms or complications if you contract COVID-19. You should continue to take them 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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