In people with moderate or severe acne, topically applied medicines are usually not sufficient to treat acne effectively. In these cases, oral medications are prescribed. Usually, your doctor will start with an oral antibiotic pill. Common pills include erythromycin, tetracycline, doxycycline or minocycline. Others, such as trimethoprim/sulfamethoxazole and azithromycin, are also used when appropriate.
These antibiotics work by treating the bacteria in the affected pores as well as by reducing the associated inflammation. Patience is needed while these pills take effect, usually 6 to 8 weeks later. For women with acne, oral contraceptive pills (birth control pills) are often prescribed. These pills work by blocking acne-causing hormones and also require patience, taking up to 3 to 4 months to show effects.
Another pill that is occasionally used is spironolactone that works by blocking the hormones that cause oil glands to become overactive. In the most severe cases of acne when other pills don't work, isotretinoin (Accutane®) is prescribed. Isotretinoin is a derivative of Vitamin A and is a very potent treatment for acne. It works by shrinking the overactive oil glands in acne pores. Treatment usually takes several months but can lead to long-lasting improvement. Isotretinoin has important possible side effects and is not appropriate for all patients. Only your doctor can determine if it is right for you.