For people taking Flomax, weight gain does not appear to be a common or rare side effect. However, if you are noticing any unexplained weight gain while taking Flomax, you should talk to your healthcare provider. He or she can do a physical exam to look for causes of unexplained weight gain. If the weight gain remains unexplained, your healthcare provider can also give you some suggestions, such as eating heart-healthy foods, exercising more, and limiting your intake of alcohol. If the weight gain continues, he or she may also recommend other lifestyle changes or a possible switch to another medicine for your enlarged prostate.
(Click BMI Calculator to see if your weight is within a healthy range.)