Acne is a very common skin disorder affecting the hair follicle. Acne is often inflammatory and is characterized by comedones (clogged pores) and pimples (papules and pustules), due in part to the excessive production of sebum (skin oil) by the sebaceous glands in the follicle. Acne is not a serious medical condition, and can usually be kept under control with treatment. Although scarring is common, treatment during and after an outbreak can help.

Acne medications heal existing acne lesions, prevent lesions from recurring and prevent scarring. They are available in both topical and oral forms. Topical treatments include gels, lotions and creams. Gels are typically alcohol–based and may dry the skin, making them better for patients with very oily skin or those who live in hot, humid climates. Lotions and creams provide moisture and are generally better for patients with sensitive skin. In some cases, a dermatologist will recommend a combination of two or more treatments. 

Many acne medications focus on preventing future eruptions instead of treating current lesions, and may take eight weeks or more to work. Often, the skin may look worse before it starts getting better. Individuals should be patient during this time, and not discontinue the medications. However, those who do not see any improvements after eight weeks should discuss possible treatment changes with their dermatologist.

Acne medications treat acne in five ways:

• Exfoliation and normalizing of skin cell production. The abnormal shedding of skin cells lining the hair follicles is addressed. Retinoids (both topical and oral) are used in treatment.
  
  
• Elimination or reduction of the acne-producing bacteria. These bacteria induce inflammation. Treatments include benzoyl peroxide and antibiotics (both topical and oral).
  
  
• Removal of materials that clog the pores. This actually addresses current blemishes. Hardened skin cells are loosened and pores are unclogged. Medications that do this are referred to as comedolytics and include retinoids, salicylic acid, alpha hydroxyl acids and azelaic acid.
  
  
• Elimination or reduction of inflammation. Current inflammation is addressed, reducing acne lesions. Salicylic acid and corticosteroid injections accomplish this. In some cases, oral nonsteroidal anti-inflammatory drugs (NSAIDs) may be used along with antibiotics.
  
  
• Reduction of sebum secretion. Sebaceous gland activity is decreased using retinoids. In hormonal forms of acne in women, certain oral contraceptives may prove useful.

In many cases, acne can be treated without a prescription. The most powerful over-the-counter acne medication is benzoyl peroxide, which reduces acne-causing bacteria within the follicle. It also helps to normalize skin cell production. Benzoyl peroxide is generally more effective when combined with topical antibiotics, particularly erythromycin. However, benzoyl peroxide can bleach fabric, hair and other colored materials.

Other acne medications available without a prescription include salicylic acid and sulfur. These are less effective than benzoyl peroxide, but have comedolytic effects. They help to break down blackheads and whiteheads and dry up sebum in active lesions. Some of these medications also have mild anti-inflammatory effects.

For patients with more serious forms of acne, or mild acne that does not respond to over-the-counter treatments, physicians may prescribe a stronger medication. Prescription acne medications include retinoids, which are derived from vitamin A. They normalize skin cell production inside the hair follicles by slowing the growth and regulating the shedding of these cells as well as preventing them from sticking together to form plugs. Many retinoids have significant anti-inflammatory properties.

Retinoids are available in topical and oral forms. Topical forms (e.g., tretinoin) have fewer negative side effects, but relapses may occur. Isotretinoin is an oral retinoid. It is the only medication that alters the natural course of acne by decreasing the size and activity of the sebaceous glands. Due to the decrease in sebum, there is a reduction of acne-causing bacteria in the follicles. Isotretinoin also has anti-inflammatory effects and normalizes skin cell metabolism. It is typically used for four to five months.

According to the National Institutes of Health (NIH), after 15 to 20 weeks of isotretinoin treatment acne goes away in up to 90 percent of patients. However, due to the potential for serious birth defects, female patients of reproductive age must sign an informed consent that they will use two different, effective forms of contraceptives for one month before treatment begins, during the entire course of treatment and for one month afterward. Monitoring with monthly pregnancy tests is also required.

Other prescription acne medications include:

• Antibiotics. These have antibacterial and anti-inflammation effects. Prescriptions may be given for topical or oral forms. Oral forms are more rapid and effective, but produce more serious side effects. One of the most effective antibiotic acne medicines is tetracycline. Others include clindamycin and erythromycin.
  
  
• Azelaic acid. Has comedolytic and antibacterial effects. Azelaic acid is used topically.
  
  
• Hormonal therapy. Corticosteroids may be injected directly into lesions to help reduce the size and pain of inflamed cysts and nodules. Also, some forms of acne that affect women are hormonal, with acne flares prior to the menstrual period. Increased androgen (male sex hormone) levels are believed to be the cause. Antiandrogen drugs (e.g., spironolactone) work by blocking androgen receptors. 
  
  Oral contraceptives contain estrogen and/or progestin and work by employing these two female sex hormones to counterbalance the effect of androgens. As a result, birth control pills may be prescribed for the sole purpose of treating acne. However, there are a wide variety of types available and not all are effective in reducing or preventing acne. Some may actually make acne worse. Oral contraceptive pills may be recommended as an acne treatment when other forms of treatment fail to improve the condition.

It is important to note that patients should not stop their medication without instruction from their physician. Many patients cease using their medication once their skin clears only to have their acne flare up a few weeks later.