Acne is a common skin condition causing pimples on the face and upper torso.

• Acne is caused by a buildup of dead skin cells, bacteria, and dried sebum that blocks the hair follicles in the skin.
• Pimples, cysts, and sometimes abscesses form on the skin, usually on the face, chest, shoulders, or back.
• To diagnose acne, doctors examine the skin.
• Common treatments include topical antibiotics for mild acne, oral antibiotics for moderate acne, and oral isotretinoinSome Trade Names
  ACCUTANE
  for severe acne.

Acne is caused by an interaction between hormones, skin oils, and bacteria, which results in inflammation of hair follicles. Acne is characterized by pimples, cysts, and sometimes abscesses. Both cysts and abscesses are pus-filled pockets, but abscesses are somewhat larger and deeper.

Sebaceous glands, which secrete an oily substance (sebum), lie in the dermis, the middle layer of skin. These glands are attached to the hair follicles. Sebum, along with dead skin cells, passes up from the sebaceous gland and hair follicle and out to the surface of the skin through the pores.

Acne results when a collection of dried sebum, dead skin cells, and bacteria clogs the hair follicles, blocking the sebum from leaving through the pores. If the blockage is incomplete, a blackhead (open comedone) develops; if the blockage is complete, a whitehead (closed comedone) develops. The blocked sebum-filled hair follicle promotes overgrowth of the bacterium Propionibacterium acnes, which is normally present in the hair follicle. This bacterium breaks down the sebum into substances that irritate the skin. The resulting inflammation produces the skin eruptions that are commonly known as acne pimples. Deeper inflammation produces cysts and sometimes an abscess.

Acne occurs mainly during puberty, when the sebaceous glands are stimulated by increased hormone levels, especially the androgens (such as testosterone), resulting in excessive sebum production. By a person's early to mid-20s, hormone production stabilizes and acne usually disappears. Other conditions that involve hormonal changes can affect the occurrence of acne as well. For example, acne may occur with each menstrual period in young women and may clear up or substantially worsen during pregnancy. The use of certain drugs, particularly corticosteroids and anabolic steroids, can cause acne by stimulating the sebaceous glands. Certain cosmetics may worsen acne by clogging the pores.

Because acne naturally varies in severity for most people—sometimes worsening, sometimes improving—pinpointing the factors that may produce an outbreak is difficult. Acne is often worse in the winter and better in the summer, perhaps because of sunlight's anti-inflammatory effect. There is no relationship, however, between acne and specific foods or sexual activity.

Symptoms

Most acne occurs on the face but is also common on the shoulders, back, and upper chest. Anabolic steroid use typically causes acne on the shoulders and upper back.

There are three levels of acne severity: mild, moderate, and severe. Yet even mild acne can be vexing, especially to adolescents, who see each pimple as a major cosmetic challenge.

Comparing Mild Acne and Severe Acne

People with mild acne develop only a few (less than 20) noninflamed blackheads or whiteheads, or a moderate number of small, mildly irritated pimples. Blackheads appear as small flesh-colored bumps with tiny, dark dots at their center. Whiteheads have a similar appearance but lack the dark dots. Pimples are mildly uncomfortable and have a white center surrounded by a small area of reddened skin.

People with moderate acne have more comedones and pimples and sometimes larger, more inflamed pimples (pustules).

People with severe (deep, or cystic) acne have numerous large, red, painful pus-filled lumps (nodules) that sometimes even join together under the skin into giant, oozing abscesses.

Acne

Scarring: Mild acne usually does not leave scars. However, squeezing pimples or trying to open them in other ways increases inflammation and the depth of injury to the skin, making scarring more likely. The nodules and abscesses of severe acne often rupture and, after healing, typically leave scars. Scars may be tiny, deep holes (ice pick scars); wider pits of varying depth; or large, irregular indentations. Acne scars last a lifetime and, for some people, are cosmetically significant and a source of psychologic stress.

Did You Know... Vigorous washing and scrubbing may irritate the skin and can make acne worse.

Treatment

General care of acne is very simple. Affected areas should be gently washed once or twice a day with a mild soap. Antibacterial or abrasive soaps, alcohol pads, and heavy frequent scrubbing provide no added benefit and may further irritate the skin. Cosmetics should be water-based; very greasy products can worsen acne. Although there are no restrictions on specific foods (for example, pizza or chocolate), a healthy, balanced diet should be followed (see Overview of Nutrition: Nutritional Requirements).

Beyond these routine measures, acne treatment depends on the severity of the condition. Mild acne requires the simplest treatment that poses the fewest risks of side effects. More severe acne or acne that does not respond to preliminary treatment requires additional treatment. A treatment plan should always include education, support, and the most practical option for the person.

Mild Acne: Drugs used to treat mild acne are applied to the skin (topical drugs). They work by either killing bacteria (antibacterials) or drying up or unclogging the pores.

The two most commonly prescribed antibacterials are the antibiotics clindamycinSome Trade Names
CLEOCIN
and erythromycinSome Trade Names
E-MYCIN ERYTHROCIN
. Benzoyl peroxideSome Trade Names
BENZAC
, another effective antibacterial, is available with or without a prescription.

Older nonprescription creams that contain salicylic acid, resorcinol, or sulfur work by drying out the pimples and causing slight peeling. These drugs, however, are less effective than antibiotics or benzoyl peroxideSome Trade Names
BENZAC
.

If topical antibacterials fail, doctors use other topical prescription drugs that help unclog the pores. The most common such drug is tretinoinSome Trade Names
AVITA RENOVA RETIN-A
. TretinoinSome Trade Names
AVITA RENOVA RETIN-A
is very effective but is irritating to the skin and makes it more sensitive to sunlight. Doctors therefore use this drug cautiously, starting with low concentrations and infrequent applications, which can be gradually increased. Benzoyl peroxideSome Trade Names
BENZAC
inactivates tretinoinSome Trade Names
AVITA RENOVA RETIN-A
, so the two must not be applied together. Newer prescription drugs with effects similar to tretinoinSome Trade Names
AVITA RENOVA RETIN-A
include adapaleneSome Trade Names
DIFFERIN
, azelaic acidSome Trade Names
AZELEX FINACEA
, and tazaroteneSome Trade Names
TAZORAC
. Blackheads and whiteheads can be removed by a doctor. A large pimple may be opened with a sterile needle. Other instruments, such as a loop extractor, can also be used to drain plugged pores and pimples.

Moderate Acne: Moderate acne is usually treated with antibiotics given by mouth. Typical antibiotics include tetracyclineSome Trade Names
SUMYCIN
, doxycyclineSome Trade Names
VIBRAMYCIN
, minocyclineSome Trade Names
MINOCIN
, and erythromycinSome Trade Names
E-MYCIN ERYTHROCIN
. Doctors often combine a topical treatment and an oral antibiotic. People may need to take antibiotics for weeks, months, or even years to prevent a recurrence. Women who take antibiotics for a long time sometimes develop vaginal yeast infections that may require treatment.

Severe Acne: For the most severe acne, when antibiotics do not work, oral isotretinoinSome Trade Names
ACCUTANE
is the best treatment. IsotretinoinSome Trade Names
ACCUTANE
, which is related to the topical drug tretinoinSome Trade Names
AVITA RENOVA RETIN-A
, is the only drug that can potentially cure acne. However, isotretinoinSome Trade Names
ACCUTANE
can have very serious side effects. Isotretinoin can harm a developing fetus, and women taking it must use strict contraceptive measures so they do not become pregnant. Other, less serious side effects may occur as well. Therapy generally continues for 20 weeks. If more therapy is needed, it should not be restarted for at least 4 months.

Other acne treatments are useful for specific people. For example, a woman with severe acne that worsens with her menstrual period may be helped by taking oral contraceptives. This treatment takes 2 to 4 months to produce results.

Doctors sometimes treat large, inflamed nodules or abscesses by injecting corticosteroids into them. Occasionally, a doctor cuts open a nodule or abscess to drain it.

Treatment of severe acne scars depends on their shape, depth, and location. Individual scars of any depth may be cut out and the skin sewn back together. Wide indented scars can be improved cosmetically in a procedure called subcision, in which small cuts are made under the skin to release the scar tissue. This procedure often allows the skin to resume its normal contours. Multiple shallow scars may be treated with chemical peels or laser resurfacing (see Noncancerous Skin Growths: Using Lasers to Treat Skin Problems). Dermabrasion, a procedure in which the skin surface is rubbed with an abrasive metal instrument to remove the top layer, also may help remove small scars. Sometimes scars are injected with various substances such as collagen, fat, or a variety of synthetic materials. These substances may raise the scarred area to make it level with the rest of the skin.

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Drugs Used to Treat Acne Drug Some Side Effects Comments Kills bacteria (applied topically) ClindamycinSome Trade Names CLEOCIN Diarrhea (rarely) — ErythromycinSome Trade Names E-MYCIN ERYTHROCIN — Well tolerated Benzoyl peroxideSome Trade Names BENZAC Dry skin Possible bleaching of clothing and hair Especially effective when combined with erythromycinSome Trade Names E-MYCIN ERYTHROCIN or clindamycinSome Trade Names CLEOCIN Unclogs pores (applied topically) TretinoinSome Trade Names AVITA RENOVA RETIN-A Irritated skin Sensitization of skin to sunlight Apparent worsening of acne when tretinoinSome Trade Names AVITA RENOVA RETIN-A is started, sometimes requiring 3 to 4 weeks before any improvement occurs Requires use of protective clothing and sunscreen during sun exposure TazaroteneSome Trade Names TAZORAC Irritated skin Sensitization of skin to sunlight Apparent worsening of acne when tazaroteneSome Trade Names TAZORAC is started, sometimes requiring 3 to 4 weeks before any improvement occurs Requires use of protective clothing and sunscreen during sun exposure AdapaleneSome Trade Names DIFFERIN Some redness, burning, and increased sun sensitivity As effective as tretinoinSome Trade Names AVITA RENOVA RETIN-A but less irritating Requires use of protective clothing and sunscreen during sun exposure Azelaic acidSome Trade Names AZELEX FINACEA May lighten skin Minimally irritating May be used by itself or with tretinoinSome Trade Names AVITA RENOVA RETIN-A Should be used cautiously in people with darker skin because of skin-lightening effects Kills bacteria (taken by mouth) TetracyclineSome Trade Names SUMYCIN Possible sensitization of skin to sunlight Inexpensive and safe, but must be taken on an empty stomach Requires use of protective clothing and sunscreen during sun exposure DoxycyclineSome Trade Names VIBRAMYCIN Possible sensitization of skin to sunlight Requires use of protective clothing and sunscreen during sun exposure MinocyclineSome Trade Names MINOCIN Headache Dizziness Skin discoloration Most effective antibiotic ErythromycinSome Trade Names E-MYCIN ERYTHROCIN Stomach upset Frequently, development of bacterial resistance to erythromycinSome Trade Names E-MYCIN ERYTHROCIN Unclogs pores (taken by mouth) IsotretinoinSome Trade Names ACCUTANE Possible harm to a developing fetus Possible effect on blood cells, the liver, and fat (triglyceride and cholesterol) levels Dry eyes, chapped lips, and drying of the mucous membranes Pain or stiffness of large joints and lower back with high dosages Associated with depression, suicidal thoughts, attempted suicide, and (rarely) completed suicide For sexually active women, requires a pregnancy test before they start isotretinoinSome Trade Names ACCUTANE and at monthly intervals while they are taking the drug, plus use of two forms of contraception or sexual abstinence, beginning 1 month before they start the drug and continuing while they take it and for 1 month after they stop taking it Requires blood tests to check whether the drug is affecting blood cells, the liver, or fat levels Drugs Used to Treat Acne Drug Some Side Effects Comments Kills bacteria (applied topically) ClindamycinSome Trade Names CLEOCIN Diarrhea (rarely) — ErythromycinSome Trade Names E-MYCIN ERYTHROCIN — Well tolerated Benzoyl peroxideSome Trade Names BENZAC Dry skin Possible bleaching of clothing and hair Especially effective when combined with erythromycinSome Trade Names E-MYCIN ERYTHROCIN or clindamycinSome Trade Names CLEOCIN Unclogs pores (applied topically) TretinoinSome Trade Names AVITA RENOVA RETIN-A Irritated skin Sensitization of skin to sunlight Apparent worsening of acne when tretinoinSome Trade Names AVITA RENOVA RETIN-A is started, sometimes requiring 3 to 4 weeks before any improvement occurs Requires use of protective clothing and sunscreen during sun exposure TazaroteneSome Trade Names TAZORAC Irritated skin Sensitization of skin to sunlight Apparent worsening of acne when tazaroteneSome Trade Names TAZORAC is started, sometimes requiring 3 to 4 weeks before any improvement occurs Requires use of protective clothing and sunscreen during sun exposure AdapaleneSome Trade Names DIFFERIN Some redness, burning, and increased sun sensitivity As effective as tretinoinSome Trade Names AVITA RENOVA RETIN-A but less irritating Requires use of protective clothing and sunscreen during sun exposure Azelaic acidSome Trade Names AZELEX FINACEA May lighten skin Minimally irritating May be used by itself or with tretinoinSome Trade Names AVITA RENOVA RETIN-A Should be used cautiously in people with darker skin because of skin-lightening effects Kills bacteria (taken by mouth) TetracyclineSome Trade Names SUMYCIN Possible sensitization of skin to sunlight Inexpensive and safe, but must be taken on an empty stomach Requires use of protective clothing and sunscreen during sun exposure DoxycyclineSome Trade Names VIBRAMYCIN Possible sensitization of skin to sunlight Requires use of protective clothing and sunscreen during sun exposure MinocyclineSome Trade Names MINOCIN Headache Dizziness Skin discoloration Most effective antibiotic ErythromycinSome Trade Names E-MYCIN ERYTHROCIN Stomach upset Frequently, development of bacterial resistance to erythromycinSome Trade Names E-MYCIN ERYTHROCIN Unclogs pores (taken by mouth) IsotretinoinSome Trade Names ACCUTANE Possible harm to a developing fetus Possible effect on blood cells, the liver, and fat (triglyceride and cholesterol) levels Dry eyes, chapped lips, and drying of the mucous membranes Pain or stiffness of large joints and lower back with high dosages Associated with depression, suicidal thoughts, attempted suicide, and (rarely) completed suicide For sexually active women, requires a pregnancy test before they start isotretinoinSome Trade Names ACCUTANE and at monthly intervals while they are taking the drug, plus use of two forms of contraception or sexual abstinence, beginning 1 month before they start the drug and continuing while they take it and for 1 month after they stop taking it Requires blood tests to check whether the drug is affecting blood cells, the liver, or fat levels

Last full review/revision August 2008 by Karen McKoy, MD, MPH