Aminosalicylates are a group of medicines used to treat inflammation of the gut that are used to treat and prevent flare-ups of ulcerative colitis.
There are quite a few available. The one that is best for you will depend upon where the inflammation is in your gut. The side-effects most commonly experienced are minor. However very rarely they can cause problems with your blood. You should tell your doctor immediately if you have any unexplained bleeding, bruising, red or purple discolouration of the skin, sore throat, or a high temperature (fever), or if you feel generally unwell during treatment.
What are aminosalicylates?
Aminosalicylates are a group of medicines that can help to control the symptoms of some inflammatory bowel (gut) diseases, such as ulcerative colitis and Crohn's disease. See the separate leaflets called Inflammatory Bowel Disease, Ulcerative Colitis and Crohn's Disease.
- Tablets or liquid to be taken by mouth.
- Liquid or foam enemas.
- Suppositories to be inserted into the back passage (rectum).
The type of aminosalicylate that you are prescribed (for example, tablet or enema) depends upon where the inflammation is in your gut.
Aminosalicylates are mainly used:
- To help keep people with ulcerative colitis in remission. That is, to keep symptoms away and prevent flare-ups.
- To treat flare-ups of ulcerative colitis.
Aminosalicylates are sometimes used to treat flare-ups of Crohn's disease. But it is not common to use them for this, as most experts now think that they are not as effective as other treatments for Crohn's disease.
There is also some evidence that if you have ulcerative colitis then taking an aminosalicylate on a long-term basis can significantly reduce your risk of developing bowel cancer.
Aminosalicylates are also used to treat some forms of arthritis. However, the rest of this leaflet is mainly about their use in inflammatory bowel diseases, in particular ulcerative colitis.
How do aminosalicylates work?
The precise way these medicines work is not fully understood. It is thought they work on the cells lining the gut to change the way the cells release certain chemicals including cytokines. These chemicals can contribute to making the gut inflamed, and may be a factor in causing the symptoms of inflammatory bowel diseases.
Are there different types of aminosalicylates?
All aminosalicylate medicines contain the active ingredient called 5-aminosalicylic acid (5-ASA). However:
Mesalazine comes in six different brand names: Asacol®, Ipocol®, Octasa®, Mezavant®, Pentasa®, Salofalk®. The way the manufacturers make each of these is a little different:
- Asacol®, Ipocol®, Mesren® and Salofalk® each have a special coating which dissolves to release the active ingredient (5-ASA) at a certain pH (acidity) within the gut.
- Each Pentasa® tablet is made up of tiny granules and the active ingredient is gradually released over the length of the gut.
- Mezavant® tablets have a special hard centre that contains 5-ASA and they have a special coating.
This means they release 5-ASA all along the colon (large intestine).
Olsalazine and balsalazide have a special chemical bond in the formulation, which bonds the active ingredient. The bond is broken to release the active ingredient by the natural germs (bacteria) that live in the colon.
Sulfasalazine (Salazopyrin®) has an additional molecule attached called sulfapyridine. Some people may not be able to take medicines with sulfapyridine included - see below for details.
The small differences in how these medicines are made, and how you take (or use) them, can be important because inflammatory bowel conditions can affect different parts of the gut. To treat your symptoms effectively, your doctor may prescribe a particular form of medication. For example:
- If your condition affects the back passage (rectum) only, you may be prescribed an aminosalicylate suppository or enema.
- If your gut is affected higher up, you may be prescribed an aminosalicylate tablet:
- Mezavant®, Dipentum® and Colazide® target the colon.
- Asacol®, Ipocol®, Mesren® and Salofalk® work a little higher in the gut in the last part of the small intestine (called the ileum).
- Pentasa® is designed to work along the entire length of the gut.
Which is the best one?
In general, medical studies show that aminosalicylates are probably equally effective. However, the evidence also suggests that sulfasalazine may cause more side-effects than the other types of aminosalicylates. Also, the one chosen may depend on the site and extent of your disease in the gut.
Can I buy aminosalicylates or are they just on prescription?
These medicines are prescription-only and are usually prescribed by a specialist doctor.
How do I take aminosalicylates?
These medicines come in a variety of forms as mentioned above. Your doctor will advise you on how to take your medication, including how often. However, in general, the tablets or capsules should always be swallowed whole and not chewed. Read the leaflet that comes with your particular brand for detailed information.
You will usually need special monitoring for the first three months of your treatment, with checks every three months after that. This involves a blood test before you start taking the medication to see how well your liver and kidneys are functioning. Your liver function will then be checked every three months while you are taking the medicines.
If you take aminosalicylates for more than a year and you have no problems then you usually only need to have blood tests every six months.
You may also be encouraged to keep a record of the frequency of your bowel movements to check how well the medication is working.
How quickly do aminosalicylates work?
Aminosalicylates may work quickly - within a week or so - to deal with symptoms that come on suddenly. In other cases they may be used continually to help to keep symptoms away and prevent flare-ups.
How long is treatment needed?
This can vary depending on the reason for treating you. In some people these medicines are used to treat flare-ups. In others they may be used on a long-term basis to keep symptoms away. Your doctor can advise you on this.
Who cannot take aminosalicylates?
Aminosalicylates may not be suitable for people with certain liver or kidney problems or for pregnant or breastfeeding women. People with a known reaction to salicylates, such as aspirin, should not take these medicines. You should also inform your doctor if you have a sensitivity to sulfonamide, a chemical used in some diuretics and anti-inflammatory medicines.
A full list of people who should not take aminosalicylates is included with the information leaflet that comes in the medication packet. If you are prescribed an aminosalicylate, read this to be sure you are safe to take it.
What about side-effects?
The most common side-effects when taking aminosalicylates are diarrhoea, headache, feeling sick (nausea) and rash. These are generally not serious. Most people who take aminosalicylates do not have any serious side-effects.
Note: a rare but serious side-effect is an effect on the blood-making cells. If this occurs it can greatly reduce the number of blood cells in your body, including the cells that fight off infection and those that help to stop bleeding. Therefore, if you develop a sore throat, mouth ulcers, unexplained bruising or bleeding, rash, high temperature (fever) or any other signs of infection, stop the medicine and report this to your doctor immediately. (As noted above, a mild rash is a common side-effect. The rash associated with this rare but serious effect on blood-making cells is different. Therefore, when taking these medicines always report a rash to a doctor who can then decide if it is a common and minor problem or the more serious rash.)
There are other rare side-effects. For example, rarely, some people taking aminosalicylates may have a hypersensitivity reaction. This may make you feel itchy, become more sensitive to sunlight or cause skin peeling. Sulfasalazine can cause a reduced sperm count in some men. This is reversible and sperm counts return to normal 2-3 months after stopping treatment.
For a full list of all possible side-effects and interactions associated with your medicine, read the leaflet that comes with your medication.
Sulfasalazine may change the colour of your urine and tears, making these fluids slightly orange. This can stain soft contact lenses in some people. If you wear contact lenses and need to take sulfasalazine it is usually recommended that you use glasses instead.
How to use the Yellow Card Scheme
If you think you have had a side-effect to one of your medicines you can report this on the Yellow Card Scheme. You can do this online at www.mhra.gov.uk/yellowcard.
The Yellow Card Scheme is used to make pharmacists, doctors and nurses aware of any new side-effects that medicines or any other healthcare products may have caused. If you wish to report a side-effect, you will need to provide basic information about:
- The side-effect.
- The name of the medicine which you think caused it.
- The person who had the side-effect.
- Your contact details as the reporter of the side-effect.
It is helpful if you have your medication - and/or the leaflet that came with it - with you while you fill out the report.
Further reading and references
Crohn's disease: management in adults, children and young people; NICE Clinical Guidelines (October 2012, last updated May 2016)
Crohn’s disease: management; NICE Guidance (May 2019)
Ulcerative colitis: management; NICE Clinical Guideline (June 2013)
Colonoscopic surveillance for prevention of colorectal cancer in people with ulcerative colitis, Crohn's disease or adenomas; NICE Clinical Guideline (March 2011)
Crohn's Disease; NICE CKS, September 2017 (UK access only)
Ulcerative Colitis; NICE CKS, July 2015 (UK access only)
Ferrari L, Krane MK, Fichera A; Inflammatory bowel disease surgery in the biologic era. World J Gastrointest Surg. 2016 May 278(5):363-70. doi: 10.4240/wjgs.v8.i5.363.