Acne is a skin condition that occurs when your hair follicles become plugged with oil and dead skin cells. It often causes whiteheads, blackheads or pimples, and usually appears on the face, forehead, chest, upper back and shoulders.

Acne is most common among teenagers, though it affects people of all age

Effective treatments are available, but acne can be persistent. The pimples and bumps heal slowly, and when one begins to go away, others seem to crop up.

Depending on its severity, acne can cause emotional distress and scar the skin. The earlier you start treatment, the lower your risk of such problems.

Acne signs and symptoms vary depending on the severity of your condition:

• Whiteheads (closed plugged pores)
• Blackheads (open plugged pores)
• mall red, tender bumps (papules)
• Pimples (pustules), which are papules with pus at their tips
• Large, solid, painful lumps beneath the surface of the skin (nodules)
• Painful, pus-filled lumps beneath the surface of the skin (cystic lesions)

If self-care remedies don't clear your acne, see your primary care doctor. He or she can prescribe stronger medications. If acne persists or is severe, you may want to seek medical treatment from a doctor who specializes in the skin (dermatologist).

For many women, acne can persist for decades, with flares common a week before menstruation. This type of acne tends to clear up without treatment in women who use contraceptives.

In older adults, a sudden onset of severe acne may signal an underlying disease requiring medical attention.

The Food and Drug Administration (FDA) warns that some popular nonprescription acne lotions, cleansers and other skin products can cause a serious reaction. This type of reaction is quite rare, so don't confuse it with the redness, irritation or itchiness where you've applied

Four main factors cause acne:

• Excess oil production
• Hair follicles clogged by oil and dead skin cells
• Bacteria
• Excess activity of a type of hormone (androgens)

Acne typically appears on your face, forehead, chest, upper back and shoulders because these areas of skin have the most oil (sebaceous) glands. Hair follicles are connected to oil glands.

The follicle wall may bulge and produce a whitehead. Or the plug may be open to the surface and darken, causing a blackhead. A blackhead may look like dirt stuck in pores. But actually the pore is congested with bacteria and oil, which turns brown when it's exposed to the air.

These factors can trigger or aggravate acne:

• Hormones- Androgens are hormones that increase in boys and girls during puberty and cause the sebaceous glands to enlarge and make more sebum. Hormonal changes related to pregnancy and the use of oral contraceptives also can affect sebum production. And low amounts of androgens circulate in the blood of women and can worsen acne.
• Certain medications- Examples include drugs containing corticosteroids, testosterone or lithium.
• Diet- Studies indicate that certain dietary factors, including skim milk and carbohydrate-rich foods — such as bread, bagels and chips — may worsen acne. Chocolate has long been suspected of making acne worse. A small study of 14 men with acne showed that eating chocolate was related to a worsening of symptoms. Further study is needed to examine why this happens and whether people with acne would benefit from following specific dietary restrictions.
• Stress- Stress can make acne worse.

These factors have little effect on acne:

• Greasy foods- Eating greasy food has little to no effect on acne. Though working in a greasy area, such as a kitchen with fry vats, does because the oil can stick to the skin and block the hair follicles. This further irritates the skin or promotes acne.
• Hygiene- Acne isn't caused by dirty skin. In fact, scrubbing the skin too hard or cleansing with harsh soaps or chemicals irritates the skin and can make acne worse.
• Cosmetics- Cosmetics don't necessarily worsen acne, especially if you use oil-free makeup that doesn't clog pores (noncomedogenics) and remove makeup regularly. Nonoily cosmetics don't interfere with the effectiveness of acne drugs.

• Age- People of all ages can get acne, but it's most common in teenagers.
• Hormonal changes- Such changes are common in teenagers, women and girls, and people using certain medications, including those containing corticosteroids, androgens or lithium.Family history. Genetics plays a role in acne. If both parents had acne, you're likely to develop it, too.
• Greasy or oily substances- You may develop acne where your skin comes into contact with oily lotions and creams or with grease in a work area, such as a kitchen with fry vats.
• Friction or pressure on your skin- This can be caused by items such as telephones, cellphones, helmets, tight collars and backpacks.
• Stress- Stress doesn't cause acne, but if you have acne already, it may increase acne

If you've tried over-the-counter (nonprescription) acne products for several weeks and they haven't helped, your doctor can prescribe medications.

Acne medications work by reducing oil production, speeding up skin cell turnover, fighting bacterial infection or reducing inflammation — which helps prevent scarring. With most prescription acne drugs, you may not see results for four to eight weeks, and your skin may get worse before it gets better. It can take many months or years for your acne to clear up completely.

The treatment regimen your doctor recommends depends on your age, the type and severity of your acne, and what you are willing to commit to. For example, you may need to wash and apply medications to the affected skin twice a day for several weeks. Often topical medications and drugs you take by mouth (oral medication) are used in combination. Pregnant women will not be able to use oral prescription medications for acne.

Talk with your doctor about the risks and benefits of medications and other treatments you are considering.

The most common topical prescription medications for acne are as follows:

• Retinoids and retinoid-like drugs- These come as creams, gels and lotions. Retinoid drugs are derived from vitamin A and include tretinoin (Avita, Retin-A, others), adapalene (Differin) and tazarotene (Tazorac, Avage). You apply this medication in the evening, beginning with three times a week, then daily as your skin becomes used to it. It works by preventing plugging of the hair follicles.
• Antibiotics- These work by killing excess skin bacteria and reducing redness. For the first few months of treatment, you may use both a retinoid and an antibiotic, with the antibiotic applied in the morning and the retinoid in the evening. The antibiotics are often combined with benzoyl peroxide to reduce the likelihood of developing antibiotic resistance. Examples include clindamycin with benzoyl peroxide (Benzaclin, Duac, Acanya) and erythromycin with benzoyl peroxide (Benzamycin). Topical antibiotics alone aren't recommended.
• Salicylic acid and azelaic acid- Azelaic acid is a naturally occurring acid found in whole-grain cereals and animal products. It has antibacterial properties. A 20 percent azelaic acid cream seems to be as effective as many conventional acne treatments when used twice a day for at least four weeks. It's even more effective when used in combination with erythromycin. Prescription azelaic acid (Azelex, Finacea) is an option during pregnancy and while breast-feeding. Side effects include skin discoloration and minor skin irritation.Salicylic acid may help prevent plugged hair follicles and is available as both wash-off and leave-on products. Studies showing its effectiveness are limited.
• Dapsone- Dapsone (Aczone) 5 percent gel twice daily is recommended for inflammatory acne, especially in adult females with acne. Side effects include redness and dryness.Evidence is not strong in support of using zinc, sulfur, nicotinamide, resorcinol, sulfacetamide sodium or aluminum chloride in topical treatments for acne.

Antibiotics- For moderate to severe acne, you may need oral antibiotics to reduce bacteria and fight inflammation. Usually the first choice for treating acne is tetracycline — such as minocycline or doxycycline — or a macrolide.

Oral antibiotics should be used for the shortest time possible to prevent antibiotic resistance.

Antibiotics may cause side effects, such as an upset stomach and dizziness. These drugs also increase your skin's sun sensitivity.

Combined oral contraceptives- Four combined oral contraceptives are approved by the FDA for acne therapy in women who also wish to use them for contraception. They are products that combine estrogen and progestin (Ortho Tri-Cyclen, Yaz, others). You may not see the benefit of this treatment for a few months, so using other acne medications with it the first few weeks may help.

The most common side effects of these drugs are weight gain, breast tenderness and nausea. A serious potential complication is a slightly increased risk of blood clots.

Anti-androgen agents- The drug spironolactone (Aldactone) may be considered for women and adolescent girls if oral antibiotics aren't helping. It works by blocking the effect of androgen hormones on the sebaceous glands. Possible side effects include breast tenderness and painful periods.

Isotretinoin- Isotretinoin (Amnesteem, Claravis, Sotret) is a powerful drug for people whose severe acne doesn't respond to other treatments.

These therapies may be suggested in select cases, either alone or in combination with medications.

• Lasers and photodynamic therapy- A variety of light-based therapies have been tried with some success. But further study is needed to determine the ideal method, light source and dose.
• Chemical peel- This procedure uses repeated applications of a chemical solution, such as salicylic acid, glycolic acid or retinoic acid. Any improvement in acne is not long lasting, so repeat treatments are usually needed.
• Extraction of whiteheads and blackheads- Your doctor may use special tools to gently remove whiteheads and blackheads (comedos) that haven't cleared up with topical medications. This technique may cause scarring.
• Steroid injection- Nodular and cystic lesions can be treated by injecting a steroid drug directly into them. This therapy has resulted in rapid improvement and decreased pain. Side effects may include thinning in the treated area.