I'm pleased that your daughter has tolerated Asacol (mesalamine). I hope it is helping to cool down her left-sided ulcerative colitis.

Asacol is generally the first drug we use to treat relatively mild ulcerative colitis. Some people experience side effects such as nausea, headache and, oddly enough, diarrhea. But most people do not develop bothersome side effects.

Your question about how long she will have to take Asacol is a good one. There are no studies that provide an answer. We know Asacol is an excellent way to keep ulcerative colitis in remission once this has been achieved. But how long it should be used depends on the extent and severity of the ulcerative colitis.

A gastroenterologist would surely recommend continuing Asacol for many months once healing occurs. Some would even recommend its lifelong use. Others doctors might taper and eventually stop the drug. (The patient could always start using the drug again if symptoms came back.)

There are other treatment options to consider when Asacol does not control flare ups. These include:

• A short course of prednisone, which is usually useful in cooling things off. (It is not used as a maintenance drug because of its inevitable side effects.
• Immunomodulators (azathioprine and 6-mercaptopurine) are used when longer-term therapy is needed.
• Anti-tumor necrosis antibodies (infliximab, adalimumab and certolizumab) can be effective for longer-term therapy. However, these drugs are potent immune system inhibitors. The potential side effects can be serious.

Other drugs are available and some are in the research pipeline. But if your daughter's left-sided ulcerative colitis, which is a more limited version of the disease, responds well to Asacol, one can hope she won't need more advanced treatments.