Acne is an inflammation of the skin that causes blackheads, whiteheads, and red spots usually called "pimples" or "zits." The most common type of acne is acne vulgaris (vulgaris means common). Acne appears most often on the face, but can also be a nuisance on your chest, back, and upper arms. Acne affects about 90% of adolescents, as well as around 20% of Canadians. It accounts for more doctor visits than any other skin problem.

Acne isn't life-threatening, but it can be upsetting and disfiguring and cause psychosocial problems. Acne can also lead to serious and permanent scarring.

Acne forms when hair follicles become blocked by dead skin cells mixed with sebum. Sebum is an oily substance produced by glands called sebaceous glands that are attached to the hair follicles. In people with acne, these glands overproduce sebum that mixes with dead skin cells to form a plug that blocks the follicles. This creates the environment for a bacteria species that commonly lives on your skin called Cutibacterium acnes to overgrow and cause inflammation.

Hormones can cause an outbreak of pimples, or increase the number you get. The hormones that are active during puberty also trigger your sebaceous glands to grow and produce more sebum. Sebaceous glands are highly sensitive to hormone changes. The hormones with the greatest effect on the oil glands are the androgens, the male hormones. Both men and women have androgens, but men have more.

In women, these hormones can also cause acne during the menstrual cycle, and that's why women often find that acne continues into adulthood.

Eating junk food and chocolate normally has nothing to do with acne. Greasy hair and skin also don’t directly cause acne on their own, but they're often a sign of overactive sebaceous glands, which can cause acne. Research suggests that stress may worsen existing acne, but it doesn't cause it directly.

A tendency to get acne can run in families. Family history can increase the chances of getting severe acne. However, the role of family history is less certain for mild acne, as young adolescents commonly have mild acne regardless of family history.

Things that irritate your skin can also cause or worsen acne. These include:

• rubbing or friction from clothing
• certain medications (e.g., corticosteroids)
• skin contact with certain sports equipment
• certain cosmetics (oil-based cosmetics)
• skin exposure to extreme temperatures

Acne symptoms vary from person to person. They include:

• blackheads (black spots the size of a pinhead) are open right on the surface of your skin (superficial) and don't leave scars
• whiteheads or pustules, the most common type of acne, are usually the first lesions people get - they don't turn black because they're not exposed to the air
• deep pustules and cysts look irritated; they're usually red and swollen with visible pus
• deep acne can be more severe – it's usually red, inflamed, warm, tender, filled with pus, and painful to touch

Deep acne often appears on the back and chest. It's usually the most difficult type of acne to treat and may leave scarring. Deep acne includes pustules and cysts, both of which can appear on the skin's surface. Some, however, are deep in the layers of the skin. If they burst, the pus that's released will cause more lesions.

Deep acne can lead to scarring. Picking at or squeezing the pimples often leaves a pitted appearance that may or may not be permanent. Scarring is more common in men because deep acne affects more men than women.

Acne is diagnosed by its appearance. Your doctor may do a physical exam and look at your medical and personal history to rule out any other possibilities. Your doctor may ask about things like cosmetics and any medications you're taking.

There are many treatments available for acne, and some people may need more than one type of therapy. Your treatment will depend on the type, location, and severity of your acne. Because it could take a while for acne lesions to mature, many of these treatments will need several months before you can judge their effectiveness. Occasionally during treatment, the acne may worsen in the beginning before it improves. Below are some of the common treatments given for acne:

Topical

• Non-prescription acne products include benzoyl peroxide, salicylic acid, and glycolic acid. When used alone, they are effective for milder cases of acne. They are peeling agents that unplug clogs and help the skin shed dead cells. Benzoyl peroxide is also antibacterial.
• Topical antibiotics can be used in combination to treat the acne bacteria that causes inflammatory acne.
• Retinoids are often used for non-inflammatory acne, but are helpful for inflammatory acne as well. They work by making your skin turn over faster and can cause skin irritation in the beginning (though this often goes away as your skin gets used to the treatment).

Topical products should be applied to the entire affected area, not just to individual pimples. There are many combination products available that contain different combinations of the above.

Oral

• For some women, taking birth control pills can help regulate the hormones that cause acne flare-ups.
• For more severe inflammatory acne, an antibiotic (e.g., tetracycline*, minocycline, doxycycline) pill may be given.
• Isotretinoin, a strong oral retinoid, is very effective in treating severe acne, but because of its potential side effects it is typically only used when multiple other treatments have failed, especially in women of child-bearing age.

Some of these treatments can make your skin more sensitive to the sun. They should be used along with appropriate sun protection. Talk to your doctor or pharmacist about the risks and benefits of the different treatment options you are considering.

Follow these basic guidelines to help prevent and treat acne:

• Wash your face twice daily with a mild, unscented soap or soap-less cleanser.
• Pat (don't rub) your skin dry with a clean towel.
• Don't pop, squeeze, or pick at pimples.
• Avoid scrubbing or vigorous washing with a harsh or rough (abrasive) soap.
• Use a fresh washcloth every day.
• Avoid the use of oil-based cosmetics.
• Keep your hair clean, and be careful about what touches your face.
• Wash off sweat and oil as soon as possible.
• Although there are no dietary recommendations for avoiding acne, some people find their acne worsens with certain foods. If that's the case, avoid consuming these foods.
• Oral steroid therapy may be given in some cases.