Ketotifen is very safe antihistamine used extensively in Europe to treat bronchial asthma and allergies. It is also being studied as a treatment for colitis. When used for asthma, weight gain and an increase in appetite are among the most frequent side effects. Ketotifen also protects the cells in the stomach, small intestine and perhaps the rest of the gut from a number of toxins. A number of case studies suggest that it may be helpful treating skin problems such as acne. Ketotifen also reduces edema (swelling and puffiness caused by water retention) around sores.