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There are several types of 5-ASA drugs:

• sulphasalazine (brand name Salazopyrin)

• mesalazine (Asacol, Ipocol, Octasa, Pentasa, Salofalk and Mezavant). This 5-ASA comes in different formulations which target slightly different parts of the digestive system. Asacol, Ipocol, Octasa and Salofalk tablets and granules have a special coating that dissolves at a certain pH (acidity) in the gut. This means that they work best in the last part of the small intestine and the beginning of the colon. Pentasa tablets and granules work throughout the gut. Mezavant tablets release their mesalazine as they pass through the large intestine (colon).

• olsalazine (Dipentum) and balsalazide (Colazide). These 5-ASAs also work best in the large intestine (colon).

Some 5-ASAs come as suppositories or enemas so may be useful if you have proctitis or inflammation in the end of your colon.

Side effects can include:

• nausea, vomiting, and watery diarrhoea
• headache and indigestion
• mild allergic reactions with rash, itchiness and fever
• less commonly, problems with the kidneys, liver, lungs and pancreas.

Sulphasalazine can cause male infertility by reducing the sperm count, but this usually resolves once the drug is stopped. Sulphasalazine can also reduce the body’s ability to absorb folates (B vitamins) which are essential for blood cell formation. Some people taking sulphasalazine may need a folic acid supplement.

It is usual to have regular blood tests while on 5-ASA treatment, especially when you first start taking the drug, to check for any unwanted side effects. You may have, for example, a blood test every three months for a year, then every six months or even annually. If you are taking sulphasalazine you may need slightly more frequent blood tests.

© Crohn’s and Colitis UK 2015