What causes acne?
No matter what your friends say, eating chocolate, fries, and other greasy food doesn't give you zits. The real culprits are your genes (acne runs in families) and testosterone, a hormone present in both men and women.
At puberty, your body starts producing more testosterone and other androgens. Besides making your voice break and causing facial hair to sprout, they make the sebaceous glands in your skin produce more oil to keep your hair nice and shiny. In families prone to acne, the oil, hair, and cells that line a pore begin to stick together and plug it up. The extra oil builds up and allows bacteria (mostly a type called Propionibacterium acnes) to grow more easily, which in turn attracts white blood cells to fight them off. The result is those dreaded pimples and blackheads that nearly all of us have had to deal with in high school.
Young men produce 10 times more androgens than young women, so they're more likely than women to develop severe acne during their teens and early 20s. Men are also more likely to have persistent cases (women's acne is typically cyclic). Thankfully, acne usually clears up on its own by the time you hit your 30s. We're not sure why, but some dermatologists believe that we eventually "burn out" the sensitive pores.
Lots of other things can trigger acne-like rashes or aggravate a breakout, including:
Changing hormone levels, especially during puberty, menstruation, and pregnancy•Hot, humid weather•Sweat, pollution, and smoke•Pressure or friction on skin from tight collars, telephones, or bike helmets•Greasy or oil-based lotions, cosmetics, and hair products •Some medications: Lithium (Eskalith, Lithane), steroids, and hormones such as testosterone and estrogenMedical experts aren't agreed that stress actually causes acne. The National Institute of Arthritis and Musculoskeletal and Skin Diseases says it doesn't but that it can make it worse. Still others say stress can produce hormonal changes that, in turn, can trigger a flareup.

I never had acne as a teenager -- why do I have it now?

Up to 80 percent of people in their 20s and 30s have acne, and it's more common among men than women. The short answer is that no one knows why some people get acne (or get worse acne) as adults. The basic cause is the same as teenage acne, and so is the treatment. If your acne developed suddenly, though, it may be worth a trip to the doctor to rule out a hormone imbalance, allergy, or the effects of the medication you're taking.
Your doctor will also be able to tell you if the rash on your skin is actually rosacea, a chronic inflammatory disorder characterized by redness in the face and neck.

What is the best way to treat acne?

One thing you shouldn't do is pick or pop your pimples. Although it may be tempting, you can cause redness and swelling, and possibly an infection or scarring. Squeezing a zit can force the infection deeper into the skin, making the problem worse.
Any well-stocked pharmacy carries a wide assortment of acne treatments -- lotions, creams, gels, solution-soaked pads, soaps, you name it. These treatments all work by preventing new outbreaks, so use them all over the areas of your skin that are prone to acne. What you choose depends on your skin type. Different ingredients do different things:
Benzoyl peroxide has an antibacterial effect and also helps dry out the oil that bacteria feed on. It actually works better on Propionibacterium acnes (P. acnes) than most real topical antibiotics such as erythromycin, but there's no compelling evidence that pricier 10 percent solutions work any better than basic 2.5 percent solutions.•Salicylic acid (beta hydroxy acid) and glycolic acid (an alpha hydroxy acid) are exfoliants -- they help break down and peel away the skin on the surface, which keeps pores clear. Stick to 2 percent solutions of salicylic acid -- higher concentrations can be very harsh.•Sulfur and resorcinol also help break down whiteheads and blackheads.•Propylene glycol and alcohol (including ethanol and propanol) are astringents -- they dry out the skin. They're usually listed under "inactive ingredients." •Water-based treatments are less drying than those with alcohol. If your skin gets too dry, the problem can be aggravated when the sebaceous glands overproduce oil to counteract the dryness.If you have sensitive or dry skin, look for a cream -- they're gentler and less irritating. If your skin is oily, you may prefer a gel, lotion, or solution because they have more astringents. Lotions spread well on hairy skin, like your chin, jaw, and hairline, but ingredients such as propylene glycol found in both gel and lotions could cause a burning irritation. Sticky strips and glue-like deep cleansing masks (such as Biore products) can be effective in pulling out superficial whiteheads and blackheads.

Are there any natural treatments for acne?

Tea tree oil, a topical antiseptic, may be worth a try. A study compared 5 percent benzoyl peroxide with 5 percent tea tree oil. Both significantly reduced the number of pimples, but tea tree oil took longer to kick in. You can find prediluted tea tree oil for spot treatment, or buy some essential oil (with at least 30 percent terpinen-4-ol) and dilute it down to 5 to 15 percent in water.
Historically, herbalists in Asia and Europe have used herbs, including burdock root to clear up acne, eczema, and other skin conditions, but there have been very few modern studies of their effectiveness. At least two Asian herbal "kampo" formulations for acne (oren-gedoku-to and keigai-rengyo-to) have been shown to kill P. acnes in lab studies.
Steaming your skin or wearing facial masks may open your pores temporarily and make it easier to remove pesky blackheads (with special tools that squeeze gently and evenly), but it won't help your acne in the long run. Homeopathic remedies for acne haven't been well studied.
Anything you do to reduce stress -- and the resulting change in hormones -- is ultimately beneficial for your skin. Try to identify your own triggers and do your best to avoid them. If your jawline is always irritated, for example, take a look at how you hold your phone to your face. If you break out before big meetings, see if regular workouts, breathing exercises, or meditation sessions help you cope. And even when a breakout clears up, continue your skincare routine to keep those zits from storming back.

When should I see a doctor?

If your acne doesn't improve after using over-the-counter products for a couple of months, consider talking to your doctor or a dermatologist, especially if your acne makes you self-conscious or interferes with your social life. About two-thirds of all teenagers want to see a doctor about their acne, but only one-third actually do. There are lots of prescription drugs available to treat acne, and there's probably one that can help you.
For moderate cases, a dermatologist may prescribe topical antibiotic medicines, usually combined with a retinoid (vitamin A analog) such as tretinoin (Retin-A and other brand names) the gentler adapalene (Differin), azelaic acid (Azelex) or the tazarotene (Tazorac), which has been approved by the Food and Drug Administration (FDA) for acne use.
Severe acne with red and inflamed pimples requires more potent oral antibiotics such as erythromycine, tetracycline, or doxycycline. If your acne doesn't respond to these treatments, your doctor may prescribe another famous vitamin A acid, oral isotretinoin (Accutane). It works by drying up the oil in your glands but since it can have side effects (including dry skin, nosebleeds, and elevated liver enzymes and blood fats) it's considered a "last resort" treatment. However, avoid Accutane if you are pregnant or considering pregnancy.

How long before I see results?

If you have a hot date coming up, be warned -- no treatment will work right away. You'll see a gradual difference in a few weeks, although it could take months for your skin to really clear up. Most dermatologists recommend sticking with a treatment for one to two months before making a change. However, if something clearly isn't working, you should ask about trying something else -- many strains of bacteria involved in acne have become resistant to certain antibiotics, and you could have a stubborn strain.

What's a good skincare routine when you have acne?

Wash your skin twice a day gently with water and a mild soap, but don't overdo it. Using a harsh soap and scrubbing too hard can actually make acne worse, and toners with alcohol can overdry your skin, especially if you're using other strong acne treatments. After a hard workout, shower and shampoo right away so sweat doesn't combine with surface oils to block pores.
Be sure to use skin-care products that won't clog your pores (these are sometimes labeled "non-comedogenic") such as oil-free skin creams and sunscreens. Also, some hairsprays and styling products can irritate your skin -- see what happens if you stop using them for a while, or switch brands if you can't tame your hair without them.
Shaving can be tricky when you have to navigate bumps and pits on your face. Electric razors can give you a close shave over scarred skin with less chance of nicking yourself. If you use a safety razor, be sure to soften the skin with soap and warm water before using shaving cream. Shave as lightly as possible on inflamed or scarred areas, and always use a sharp blade.

What can I do about severe acne scars?

Dermatologists and plastic surgeons have a host of methods to repair skin scarred by acne. Chemical peels employ an acid to dissolve the superficial top layers of damaged skin. In dermabrasion, a wire brush buffs or sands down irregular acne scars. Microdermabrasion is a technique in which aluminum oxide crystals are used to gently scrape away the scarred skin. Repeated treatments may be needed. Lasers are used to fix complex scars by vaporizing the outer layers of skin so the underlying skin will eventually heal more tightly and smoothly. Doctors can also inject fat or other filler substances into depressed scars to soften the scar tissue and minimize the pitting.