What is the cause of acne?

Acne is the most common skin condition that people experience. Most people develop acne to some degree, but it primarily affects teenagers undergoing hormonal changes. Acne might be mild (few, occasional pimples), moderate (inflammatory papules), or severe (nodules and cysts). Scarring can occur. Treatment depends on the severity of the condition.

Acne is primarily a hormonal condition driven by male hormones, which typically become active during the teenage years. Sensitivity to such hormones — combined with surface (skin) bacteria and lipids (fatty acids) within sebaceous (oil) glands — yields acne. Common sites for acne are the face, chest, shoulders, and back—the sites of oil glands.


Acne lesions include comedones (whiteheads, blackheads), papules and pustules (small bumps, often with scarring), nodules, and cysts, often followed by scarring.

Although acne is essentially a normal physiologic occurrence, certain conditions might aggravate the disease.

  • Fluctuating hormone levels around the time of menses (women)
  • Manipulating (picking/prodding) acne lesions
  • Occlusive clothing and headgear, such as hats and sports helmets
  • Air pollution and certain weather conditions, especially high humidity

What is the treatment for acne?

Only three medicines have proven to be effective for the treatment of acne—benzoyl peroxide, retinoids, and antibiotics. Most patients require at least one or two agents, depending on disease severity.

  • Benzoyl peroxide is available as an over-the-counter product (such as Clearasil®, Stridex®) and by prescription (such as Benoxyl, PanOxyl®, Persagel). It targets surface bacteria, which often aggravate acne. Irritation (dryness) is a common side effect.
  • Retinoids (vitamin A derivatives) — such as Retin-A®, Differin®, and Tazorac® — are comedolytic, meaning they lyse or "break up" comedones (blackheads and whiteheads), the first lesions of acne. Most patients are candidates for retinoid therapy. The most common side effect is irritation.
  • Antibiotics, either topically applied to the skin (clindamycin, erythromycin) or taken systemically (tetracycline and its derivatives) control surface bacteria that aggravate and often foster acne. Antibiotics are more effective when combined with benzoyl peroxide or retinoids.

The oral retinoid isotretinoin (Accutane®) is reserved for those patients with severe (nodular or cystic) disease. Accutane shrinks the size of oil glands, the anatomic origin of acne. Without active, plump oil glands, acne actively diminishes. Side effects can be worrisome (dry skin, elevated lipids) and even devastating (birth defects). Women of childbearing age must practice birth control before and during treatment with Accutane, and for several months afterward, often a year. The use of Accutane requires rigorous testing (lipids, pregnancy) and follow-up for the prescribed period (five months).

Hormone therapy might be helpful for some women with acne, especially for those with signs and symptoms (irregular periods, thinning hair) of androgen (male hormone) excess. The hormone therapy consists of low-dose estrogen and progesterone (birth control pills).


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What causes acne?

The exact cause of acne is not known, but one important factor is an increase in hormones called androgens. These male sex hormones increase in both boys and girls during puberty. Some things that can make acne worse include friction caused by leaning on or rubbing the skin, harsh scrubbing, picking or squeezing blemishes, and emotional stress. Acne is not caused by chocolate, fatty foods, or other kinds of foods.

What is the best treatment for acne?

Over the counter medications, such as Clearasil, may be helpful for mild acne, but they are of little use for those with significant disease. Depending on an individual’s particular situation, there are a variety of medications that may help including:

Benzoyl peroxides, which can be purchased without a prescription, kill bacteria but promote a mild degree of skin irritation. This product is available as bar soap, liquid wash, cream lotion and gel.

Topical antibiotics such as the sulfa drugs erythromycin and clindamycin are not available without a prescription. These products benefit people with mild to moderate disease acne and usually do not produce side effects.

Azeolic acid, applied to the skin once or twice daily, is safe and effective for mild acne. However, it can bleach the skin in persons with pigmented skin.

Oral antibiotics are effective for moderate to severe acne. However, some studies have shown that their use in patients taking oral contraceptives can cause the birth control pill to fail. Those who have known allergies to specific antibiotics should inform their physician.

Retinoids are a derivative of Vitamin A. derivative. The topical form (RetinA, Differin or Avita) is used for patients with mild to moderate acne. The oral form (Accutane) is prescribed for severe, disfiguring acne, and, in select cases, is the only medication that helps. Its disadvantages include sun sensitivity and its potential to cause severe birth defects if taken during pregnancy.

Comedogenicity – What is it and how can it be prevented?

Acne-like plugs in skin pores which may appear after a few months of using some cosmetics are medically known as comedones. This condition is not to be confused with irritation from cosmetic which happens very quickly. Typically, comedogenic reactions to cosmetic ingredients occur in oily areas of facial skin. Since the offending product itself, or its ingredients, may not be oily or greasy, how can you tell if a cosmetic is likely to clog pores?

Your best defense against developing comedones is to become familiar with the terminology and ingredients on the labels of your cosmetic products. For example, "oil-free" and "non-comedogenic" do not necessarily have the same meaning because some comedogenic ingredients are not oils. And some ingredients, such as mineral oil and petrolatum, are not comedogenic, even though their names suggest they might be. "Natural" does not mean non-comedogenic because many natural oils, such as coconut oil, are known to clog pores.

Here are a few guidelines to consider when selecting a cosmetic product:
  • If your skin is acne-prone, avoid cosmetics in a cake form. Highly comedogenic agents are routinely added to pressed foundations and blushes to maintain their shape.
  • Choose water-based products, because they usually contain fewer comedogenic ingredients.
  • Be cautious with powdered products, although "loose" is better than "pressed."
  • Visible aging of the skin is caused mostly by photodamage and not dry skin. Choose a sunscreen in a non-comedogenic formulation to help reduce sun exposure.