If your symptoms do not improve within a few days or if they become worse, check with your doctor.
Serious skin reactions can occur with this medicine. Stop using this medicine and check with your doctor right away if you have any of the following symptoms: a skin rash; blistering, peeling, or loosening of the skin; cough; diarrhea; itching; sores, ulcers, or white spots in the mouth or on the lips; or unusual tiredness or weakness.
Check with your doctor right away if you have fever; chills; joint or muscle pain; pale skin; pinpoint red or purple spots on the skin; shortness of breath; sore throat; pain in the upper stomach; or yellow eyes or skin. These may be symptoms of a serious blood problem.
Sulfisoxazole may cause diarrhea, and in some cases it can be severe. Do not take any medicine to treat diarrhea without checking first with your doctor. Diarrhea medicines may make the diarrhea worse or make it last longer. If mild diarrhea continues or gets worse, check with your doctor.
Do not take other medicines unless they have been discussed with your doctor. This includes prescription or nonprescription (over-the-counter [OTC]) medicines and herbal or vitamin supplements.