Acne

• What is acne?
• Antibiotics for acne
• Topical antibiotics
• Retinoids for acne

Acne (also called acne vulgaris) is a common skin disease characterized by clogged pores and pimples, blackheads, or red, swollen bumps. Acne lesions are most common on the face, but they can also occur on the neck, chest, back, shoulders, scalp, and upper arms. Acne lesions are referred to as pimples, spots, or zits.

Severe acne is inflammatory, but acne can also manifest in noninflammatory forms.

More than four out of five people between the ages of 12 and 24 have acne at least once. But while acne is often associated with teenagers, it can affect people of all ages.

Acne is rarely a serious medical condition, but it often causes emotional distress and can lead to scarring of the skin.

Acne seems to affect the sexes somewhat differently. Before children reach puberty, it is more commonly seen in girls. During puberty, acne affects boys and girls almost equally, but boys generally have more severe cases. In adulthood, it tends to be seen more often in women.

Acne lesions range in severity from comedones (blackheads and whiteheads) to nodules and cysts.

• Blackheads occur in partially blocked pores. Dead skin cells, bacteria, and sebum drain to the surface of the skin. The pigments are exposed to air, which causes the black color.
• Whiteheads are slightly raised, skin-colored bumps, develop from a blockage deeper in a pore. Lacking a drainage path, the oil accumulates in the skin, causing small flesh-colored or white-colored bumps. Unlike blackheads, whiteheads are more likely to lead to the inflammation known as pimples or zits.
• Papules are inflamed lesions that usually appear as small, pink bumps on the skin and can be tender to the touch.
• Pustules are closed comedos, which become inflamed and begin to rupture into the skin forming pustular heads of various sizes.
• Nodules represent large, tender, swollen acne lesions, which have become intensely inflamed and rupture under the skin. If untreated, these can produce deep scarring.
• Cysts are deep, painful, pus-filled lesions that can cause scarring.

Acne occurs when the hair follicles become plugged with oil and dead skin cells. However, the exact cause why some people get acne and some do not is unknown.

Several factors are known to be linked to acne:

• Genetic predisposition. Researchers believe that the tendency to develop acne can be inherited from parents.
• Hormones likely play a role in the development of acne, making the condition most common in teenagers. Some adult women experience mild to moderate acne due to hormonal changes associated with pregnancy and their menstrual cycles. Higher levels of sex hormones (like testosterone and androsterone) stimulate oil production by the glands surrounding hair follicles. This excess oil clogs these follicles or pores, thus causing a pimple.
• Greasy cosmetics may alter the cells of the follicles and make them stick together, producing a plug.

Whichever treatment is used, it is normal to take up to four weeks to see any noticeable improvements in the skin. There is often a good response by six weeks. However, it can take up to four months (sometimes even longer) for maximum response, and for the skin to be generally free of spots.

The main reason for a treatment failure is because some people think that it is not working after a couple of weeks or so, and give up.

Once the spots have cleared, acne commonly flares up again if you stop treatment. Therefore, after the spots have gone or are much reduced, it is better to carry on with a 'maintenance' treatment to prevent acne from flaring up again.

The maintenance treatment may continue for 4-5 years to keep acne away. This is typically until the late teens or early 20s. Sometimes, acne persists into the 30s, or even later. For these people it is possible to continue maintenance treatment with a topical benzoyl peroxide or a topical retinoid.

Antibiotics are effective in treating most inflammatory acne (papules and pustules). They work by killing the acne causing skin bacteria - Propionibacterium acnes. Antibiotics also work by decreasing the redness and swelling seen in the inflammatory forms of acne. However, they have little effect on unplugging blocked pores, which are blackheads and whiteheads.

Antibiotics are usually started with a higher dose, which is reduced as acne resolves. Generally, treatment lasts for six months or less. Over time, the P. acnes bacteria can become resistant to the antibiotic being used. Then another antibiotic or alternative treatment can be chosen to control acne.

Tetracyclines are the most commonly used antibiotics to treat acne. They reduce the papules and pustules of acne. Tetracyclines should not be taken by children younger than 8 years of age because they can affect growth and stain teeth. They should also not be taken by a woman who is pregnant or breast feeding.

Tetracycline is the most widely prescribed antibiotic for acne. The usual starting dose is 500 mg twice a day continued until a significant decrease in acne lesions is seen. The dose can then be decreased to 250 mg twice a day or discontinued. The main drawback for this antibiotic is that it must be taken on an empty stomach to be the most effective. For a teenage boy who eats frequently, this can be very difficult.

Doxycycline proves especially effective in treating inflammatory acne. This antibiotic is better tolerated than tetracycline. Doxycycline is started at 50 to 100 mg twice a day. Doxycycline is more likely than tetracycline to increase sensitivity to the sun, or cause sunburns.

Minocycline has a long history of use to treat acne. It is often effective in treating acne that has not responded to other oral antibiotics. Minocycline is especially useful for pustular type acne. Minocycline also seems to produce fewer incidents of antibiotic resistance. While the absorption is decreased with food, it is not as significant as the decrease seen with tetracycline. The usual starting dose is 50 to 100 mg twice a day.

Antibiotics may be taken orally or applied to the skin in the form of gels and lotions. Giving an antibiotic by mouth is often needed for acne that is more extensive, red, and tender.

Topical antibiotics work by killing the Propionibacterium acnes bacteria. This also indirectly keeps the pores open.

Clindamycin
Topical clindamycin has a long history of successfully treating acne. It works by killing P. acnes and decreasing inflammation. In topical form, clindamycin has proven to be safe and is well tolerated. Skin dryness and irritation are possible troubles. It is important to use clindamycin as directed to decrease bacterial resistance that can occur with antibiotic.

Erythromycin
Topical erythromycin is an antimicrobial and anti-inflammatory. The combination of topical erythromycin with benzoyl peroxide proves to be quite effective. Like topical clindamycin, erythromycin may cause skin dryness and irritation. Erythromycin is safe for use by pregnant women.

Retinoids are synthetic vitamin A derivatives. Medicines made from vitamin A are useful in treating several types of acne lesions.

Some common topical retinoids include:

• Adapalene (Differin)
• Tretinoin
• Tazarotene (Avage)
• Tazarotene (Tazorac)

Topical retinoids are prescribed to treat acne ranging from mild to moderately severe. These help to open clogged pores by creating a mild peeling effect. Topical retinoids work by increasing skin cell turnover promoting the extrusion of the plugged material in the follicle. They also prevent the formation of new comedones and may help diminish the signs of aging, such as fine lines and wrinkles.

Topical retinoids can dry and irritate the skin and increase sun sensitivity. So it is important to use sun protection and follow the dermatologist’s directions to maximize effectiveness.

Retinoids are very effective. It may take 6-9 weeks to see a noticeable difference. It takes at least 6 months to see a noticeable difference in wrinkles.

Oral retinoids are reserved for treating the more extensive nodular type of acne or severe inflammatory acne, which has not responded to other treatments. Oral retinoids not only have a peeling effect but also decrease the production of oil.

Isotretinoin (known as Accutane) is classified as a retinoid, made from a synthetic form of vitamin A. Isotretinoin works by shrinking the sebaceous glands within the dermis, reducing the production of oil. The reduction of oil within the follicle means less clogging of the pores, leading to a reduction of overall breakouts.

Treatment course lasts for 16 to 20 weeks followed by a period of rest. Usually one course is enough. However, if sufficient clearing is not achieved, more courses are prescribed.

Isotretinoin may cause miscarriage and severe birth defects if taken during pregnancy.

Oral contraceptives are often prescribed for hormonal acne. While only Ortho Tri-Cyclen and Estro-Step are currently approved by the FDA for this indication, experts agree that contraceptives improve acne regardless of which formula is used.

Oral contraceptives have been shown to effectively clear acne in women by suppressing the overactive sebaceous glands and can be used as long-term acne therapy.

It is important to know that in some cases oral contraceptives may make acne worse. They should be initiated only after the advice of a gynecologist.

Azelaic acid

Azelaic acid, naturally occurring in the skin, is used to treat mild to moderate inflammatory and non-inflammatory acne. It is believed that azelaic acid clears acne by reducing the populations of P. acnes, decreasing the abnormal shedding of skin cells and reducing inflammation. Also, it can lighten the dark spots left by acne.

Azelaic acid is well tolerated by most people and can be safely used for years. It may cause skin dryness and lightening of the skin where applied.

Azelaic acid is as effective as tretinoin and may have even more beneficial effects when used with tretinoin.

Benzoyl peroxide

Benzoyl peroxide is a good choice for people with mild acne. It works by killing bacteria P. acnes. However, it does not have anti-inflammatory properties. It is available in a wide range of strengths and can be found as a gel, lotion, cleanser, cream and wash.

Many acne preparations include benzoyl peroxide because research shows that benzoyl peroxide increases the effectiveness of some medicines, such as erythromycin and clindamycin. When used in combination with antibiotics, benzoyl peroxide also reduces the likelihood of developing resistance to the antibiotic.

Salicylic Acid

Salicylic acid belongs to a group of medicines known as keratolytics. It helps slow down shedding of the cells inside the follicles, preventing clogging. Salicylic acid also helps break down blackheads and whiteheads. All strengths are available over-the-counter.

• 1. The Merck Manual of Medical Information. Mark H. Beers et al., eds. 2nd Home Edition. Whitehouse Station, NJ: Merck; 2003.

Published: July 20, 2009
Last updated: May 29, 2011