Belonging to a class of medications called topical antibiotics, the combination of erythromycin and benzoyl peroxide is typically used to treat acne by killing the bacteria that cause it. Plus, it comes as a gel that is usually applied to the skin twice a day, in the morning and evening. Remember to follow the directions on your prescription label carefully, and ask your doctor or pharmacist to explain any part you do not understand. Besides, you should not use more or less of it, or use it more often than prescribed by your doctor. It’s also preferable that you avoid unnecessary or prolonged exposure to sunlight and to wear protective clothing, sunglasses, and sunscreen, considering Erythromycin and benzoyl peroxide may make your skin sensitive to sunlight. In addition, this combination may cause other side effects such as dry skin, burning or redness of the skin. In fact, it may also cause serious side effects, including severe diarrhea, severe stomach cramps, hives, and eye or eyelid irritation and swelling. It is worth noting that animal reproduction studies have shown an adverse effect on the fetus, yet there are no adequate and well-controlled studies in humans, but potential benefits may warrant use of this drug in pregnant women despite potential risks.