Aminosalicylates (5-ASAs) for IBD 

Points to remember

  • 5-ASAs are safe and effective medications to treat inflammatory bowel disease (IBD).
  • There are various types and forms of 5-ASAs. These include oral tablets, liquid enemas, foam enemas and suppositories. The most appropriate one will depend on the location, type and severity of your IBD.

Key points 

  • 5-ASA medications reduce swelling and irritation (inflammation) in certain places in the gut.
  • There are many different 5-ASAs and different ways to take them. Some will come in tablets while others as suppositories.
  • Patients taking a 5-ASA may have blood tests done every 6-12 months to check the health of your liver and kidneys.
  • Common side effects of 5-ASAs may include headaches, abdominal pain or discomfort, nausea, vomiting, diarrhoea and loss of appetite. 

What are 5-ASAs and how do they work?

Aminosalicylates (5-ASAs) are a group of medications used to treat IBD. There are many medications within the group, including mesalazine, balsalazide, olsalazine and sulfasalazine.

The immune system is important for fighting infections but in IBD, there is an imbalance in the immune system which can cause chronic inflammation. Inflammation in the bowel can cause damage to intestinal lining, diarrhoea, and bleeding.5-ASAs act locally on the bowel to reduce this inflammation. It may take a few weeks after starting 5-ASAs to feel the full benefits.

Depending on the location of inflammation in your bowel you may be prescribed an oral 5-ASA which releases and acts at a specific part of the bowel, or a rectal 5-ASA which comes in contact with the end of the large bowel or the rectum. Sometimes a combination of oral and rectal 5-ASAs may be used to manage inflammation and symptoms.

One of the types of 5-ASA, sulfasalazine, may also have some effect on inflammation in other parts of the body such as joints.

Why have I been prescribed a 5-ASA?

5-ASAs are used to reduce and control symptoms for patients with mild to moderate ulcerative colitis and some forms of Crohn’s disease.

How do I take 5-ASAs?

There are many different forms and brands of 5-ASAs which all have specific instructions on how to take them. Some general information is provided below, refer to the product information or discuss with your IBD team if you are unsure how to take them.

Oral 5-ASAs


Many brands of 5-ASAs have a special coating around the tablet that allows the medication to be released in the correct part of the bowel. It is important to not crush or chew the tablet as this will damage the coating. Depending on brand the tablet may be best taken with food or on an empty stomach.


Some brands come as granules which are smaller than tablets. Granules are taken by placing them on the tongue and swallowing with plenty of liquid and without chewing.

Rectal 5-ASAs

Rectal 5-ASAs are used where the inflammation is found in the left side of the colon (enemas) or in the rectum only (suppositories). Depending on the location of inflammation in your bowel an enema or suppository may be more appropriate; your IBD team will work with you for the best choice.

Enemas come in foam or liquid form. Enemas use a special applicator that is inserted into the rectum and can deliver medication up into the colon. A foam enema may sometimes be better tolerated when the rectum is inflamed.

Suppositories are solid dosage forms of medication that are inserted into the rectum and dissolve over time.

Your IBD team will give you advice on how to administer rectal treatments and address any concerns you may have.

What checks will I need while I am taking a5-ASA?

Patients taking a 5-ASA may have blood tests done every 6-12 months to monitor liver and kidney function.

How long will I be on a 5-ASA?

The dosing and use of 5-ASAs may change over time as you respond to treatment. Generally, oral tablets are given at a higher dose to begin with and may reduce to a maintenance dose once your symptoms have improved and are stable for a period of time.

Rectal 5-ASAs are often prescribed in addition to oral therapy for short term management of flares, and can also be used long term to maintain symptom control.

Your IBD team will discuss with you when it is appropriate to change your 5-ASA therapy.

Fertility, pregnancy and breastfeeding

Mesalazine, balsalazide and olsalazine have no effect on fertility.

Sulfasalazine does reduce the quantity of male sperm, which returns to normal within 3 months of stopping the medication. Males wanting to conceive should be switched to an alternative type of 5-ASA. Sulfalsalazine has no effect on female fertility.

It is important your IBD is controlled on effective medication before becoming pregnant. Tell your doctor if you are thinking of becoming pregnant or find you are pregnant. Both oral andrectal forms of mesalazine, balsalazide and olsalazine are considered safe for use during pregnancy. Sulfasalazine is also safe during pregnancy, but it is recommended women take folic acid supplementation while on this medication as it can reduce folate levels. Most IBD doctors recommend continuing 5-ASAs while pregnant as there may be a greater risk to the baby if you become unwell from stopping treatment.

All 5-ASAs are excreted into breastmilk but are considered safe for use. Infants should be monitored for any intolerance to this small amount, with vomiting, diarrhoea or allergic reactions rarely reported with some 5-ASAs.

What are the possible side effects of a 5-ASA?

All medications can cause side effects, but not everyone experiences them. You will be monitored for side effects by your IBD team.

More common side effects you may experience include headache, abdominal pain or discomfort, nausea, vomiting, diarrhoea and loss of appetite. Rare side effects have been described in a few people. These include inflammation of the liver, reduced kidney function, inflammation of the pancreas (pancreatitis) and some blood disorders.

Mild allergic reactions such as localised rash or itch may occur. Stop the medication and discuss with your IBD team and/or local doctor if this occurs. If you develop a severe allergic reaction including shortness of breath, chest pain or swelling of the lips, throat or face stop the medication and seek urgent medical attention.

Sulfasalazine may cause a yellow-orange discolouration of body fluids including sweat, tears and urine. Soft contact lenses may be discoloured if worn. This colour change is not harmful but is part of how your body processes this medicine.

What can I do to keep myself healthy on a 5-ASA?

  • Have regular blood tests as recommended by your IBD team.
  • Always check with your IBD team before starting new medications to avoid unwanted interactions.
  • You should have the flu vaccine every year, and the COVID-19, pneumonia, and human papilloma virus (HPV) vaccines according to the recommended schedule. Please refer to the Vaccinations and IBD information sheetfor further information.
  • Women should have regular cervical screening tests as recommended by your GP.

Contact the IBD team or your GP if you have an infection or persistent fever.

This information leaflet has been designed to provide you with some important information about Aminosalicylates. This information is general and not intended to replace specific advice from your doctor or any other health professional. For further information please speak to your pharmacist, doctor or IBD nurse.


This resource was developed in 2021 by the GESA IBD Patient Information Materials Working Group