5-ASA are often used to treat mild to moderate flare-ups of UC. They may then be prescribed to maintain remission and help prevent flare-ups on a longer term basis. The rectal delivered 5-ASA (enemas and suppositories) are really important for helping with symptoms of urgency as they target the distal colon.
The use of 5-ASA for Crohn’s disease is more controversial. Some 5-ASA may help to control very mild CD in the ileum and colon. However, there is little evidence that 5-ASA are effective in maintaining remission, although they may help reduce the chance of CD reoccurring after surgery. 5-ASA are not recommended for severe CD.
Some 5-ASA work best in certain parts of the gut, so you may be prescribed a particular type or brand depending on where you have the inflammation. Many specialists in IBD believe that if a particular brand or type of 5-ASA is working well, you should not be switched to another without a good clinical reason.
Oral 5-ASA were previously prescribed in two or three doses during the day. However, recent evidence suggests that taking these together in a single daily dose can be just as effective. If you feel this could be helpful for you, discuss this with your doctor.
Some 5-ASA come as suppositories or enemas so may be useful if you have proctitis (inflammation of the rectum) or proctosigmoiditis (inflammation of the rectum and sigmoid colon).
There are some similarities between 5-ASA and aspirin and therefore there is a concern of possible cross-reactivity
There has been a report of successful use of 5-ASA in a patient with aspirin allergy by first using a test dose
You will have to discuss with your IBD specialist whether to pursue a supervised test dose to assess tolerability or consider desensitization (trying to overcome the allergy by slowly introducing small doses and gradually increasing to full dose)
There may be cross-reactivity if you have a sulfa allergy and therefore alternative medications to sulfasalazine should be considered instead.