University Health Service

What is acne?

Acne is one of the most common skin problems, affecting about 90% of all people at some time during their life. While acne usually occurs in adolescence and young adulthood, it may be troublesome well into the 20s, 30s and even 40s.

Misinformation about acne often prevents proper treatment. Many people do not seek the advice of a clinician because acne is common and will "probably go away by itself." While this may be true, much cosmetic damage and psychological anguish can be avoided if acne is controlled from the start.

How acne develops:

The skin's sebaceous glands, attached to hair follicles, secrete an oily semi-fluid substance called sebum that softens and lubricates our hair and skin.

Pores and hair follicles become plugged with sebum, dead skin cells, bacteria, and other debris. Whiteheads or blackheads form just below the skin surface.

  • Whiteheads (also called closed comedones) occur when the backed-up material is trapped below the skin's surface, forming a firm white bump.
  • Blackheads (also called open comedones) occur when the backed-up material stretch the duct and its opening and become exposed to air. The resulting discoloration is not dirt but oxidation of gland products and accumulation of pigment. (Some individuals have large skin pores; these are not blackheads but rather a normal variation of skin.)

Pimples (or pustules) occur when the material remains backed up, irritates surrounding tissues and causes inflammation, redness and perhaps discomfort.

In severe cases of acne, cysts (fluid-filled sacks) develop. Without proper treatment, cysts may increase the likelihood of scarring.


Pores and hair follicles can become plugged for a variety of reasons.

  • Hormones: At puberty, the body begins producing more androgen-type hormones, which cause the sebaceous glands to enlarge and produce more sebum. Because males produce more androgens than females, they tend to have more severe cases of acne.
  • Heredity influences the size and activity of the sebaceous glands. The larger and more active the glands are, the greater the chance of developing acne.
  • Bacteria: Normal skin bacteria (e.g. propionibacterium acnes) can act upon sebum to produce irritating substances, resulting in inflammation when the substances are released into surrounding skin.

Other contributing factors and self-care:

  • For those with a few blackheads or pimples, washing the face gently with a mild soap 2-3 times a day may be enough. However, excessive cleaning can make acne worse. See also Acne Cleansers and Soaps. Also, non-prescription products with benzoyl peroxide have an antibacterial and drying effect and help unblock pores to prevent formation of lesions.
  • Certain foods, such as chocolate and colas, do not cause acne as was once believed. However if you feel certain foods aggravate your acne, avoid those foods.
  • Avoid tight-fitting clothes and gear, such as sweat headbands and turtlenecks.
  • Certain cosmetics, hair care products and moisturizers may block pores. Check labels and choose products that are water-based, oil-free and non- comedogenic (won't clog pores).
  • Oily hair may contribute to clogging the surface of pores, so shampoo hair regularly.
  • Do not pick or squeeze blackheads, whiteheads or pimples, because this can cause infection, increased inflammation and scarring.
  • Emotional stress may worsen acne - see Stress and Mental Health for suggestions to manage stress.
  • Excessive humidity may make acne worse.
  • Certain drugs, especially steroids or those containing iodine, may affect acne. Talk to your clinician about side effects and treatment options.
  • Onset of menstruation, for some women, increases acne.

Medical treatment:

Based on severity and individual needs, a clinician may recommend some of the following treatments to control acne. None of these is an overnight remedy; they all must be used for a number of months to determine their effectiveness for any individual. Acne may initially flare up when the treatment begins.

Acne cleansers and soaps remove oil and bacteria from the skin surface. However, sebum production occurs deep in the sebaceous glands, not on the skin surface, so acne cannot be scrubbed off mechanically. Cleaning is a very small part of acne treatment. Once oil reaches the skin surface, few problems are caused except for the oily appearance that most people do not like. Excessive cleaning (e.g. scrubbing or use of abrasive cleaners) may provoke inflammation and actually make acne worse

Topical agents are applied to the skin for treatment of mild to moderate acne. These medications may be used individually or in combination.

  • Benzoyl peroxide products (non-prescription and prescription forms) have an antibacterial and drying effect.
  • Topical antibiotics (by prescription only) may decrease bacterial population on the skin and in the pores, altering the composition of sebum and reducing the inflammatory process. Examples include clindamycin, erythromycin and metronidazole. Use of these products alone may lead to bacterial resistance, so they are often used in combination with benzoyl peroxide.
  • Retinoids, available by prescription, such as Retin-A (tretinoin), Differin (adapalene) or Tazorac (tazarotene) and other keratolytic agents (alphaglycolic, salicylic or lactic acid) act primarily to unblock pores and prevent formation of blackheads and whiteheads. Some of these preparations can be quite drying as well as irritating. Because retinoic acid is derived from vitamin A, some people have attempted to self-treat their acne by taking large amounts of vitamin A supplements. This is not recommended because vitamin A taken by mouth does not have the same effects as topical vitamin A and because serious side effects, including liver damage, could result from this practice. All of the retinoids decrease the skin's natural UV protection, making users of these products more sensitive to sun exposure and increasing risk of sunburn. Therefore, avoid prolonged exposure to sun and sunlamps and use sunscreen daily.

Oral antibiotics (available by prescription only) decrease bacteria on the skin, alter sebum composition and/or reduce inflammation. They may be recommended for moderate to severe acne or acne that has not responded to topical medications. However, improvement may not be apparent for up to three months after treatment begins. Oral antibiotics may be used in combination with some topical agents. Common types include tetracycline, minocycline, erythromycin and doxycycline.

Hormone pills (by prescription only) that include spironolactone and cyproterone acetate shrink sebaceous glands, decreasing the amount of sebum produced. Most women who take birth control pill notice no change in acne but some note an increase or decrease in acne. Males should not take hormone pills due to side effects (e.g. breast enlargement, inability to achieve or maintain erection).

Accutane (isotretinoin, by prescription only) is a synthetic vitamin A derivative, used since 1982 for treatment of severe inflammatory cystic acne that has not responded well to other treatments. This medication requires careful medical supervision because of side effects and precautions. For example, pregnant women should not use Accutane because it causes birth defects in nearly 100% of cases.

Surgery includes extraction of blackheads or whiteheads, cryosurgery (a freezing technique) and injection of steroids into the lesions. These methods can be used to treat individual lesions as an adjunct to overall management of acne.

For more information:

UHS clinicians manage acne and can treat most cases. If additional consultation is needed, the clinician will refer students to a dermatologist at UHS. You must have a referral (written consultation request) from a UHS clinician to visit a dermatologist. To visit UHS, see Schedule an Appointment.

The UHS Pharmacy carries acne products.

AcneNet  offers extensive information about acne, treatment and skin care from the American Academy of Dermatology.