Passing gas is the most common side effect of Bactrim, states Drugs.com. Other potential side effects include weight loss, discouragement, lack of caring and a feeling of constant movement of self or surroundings. Some people may experience a feeling of emptiness or sadness, trouble sleeping or concentrating, irritability and an increased sensitivity of the skin to sunlight. Bactrim can also cause severe sunburn, a sensation of spinning, a lack of feeling or emotion, and a lack of pleasure or interest.
Some people may see, hear or feel things that are not there after taking Bactrim, notes Drugs.com. Bactrim may cause redness or other discoloration of the skin and nervousness. These side effects may not require medical attention, and they may subside after the body becomes accustomed to the medication; however, it is a good idea to check with a health care professional if they persist or become bothersome.
Rare side effects that require medical attention include stomach or abdominal pain; black, tarry stools; dark urine; and blistering, peeling or loosening of the skin, advises Drugs.com. Other serious but rare side effects include nausea, chest pain, lower back or side pain and red, irritated eyes. There are many other potentially serious side effects associated with Bactrim, so to be safe, patients should speak to a physician if side effects occur.