About 80 percent of teenagers are affected by acne between the ages of 13 and 17. However, many middle aged people also experience acne symptoms.

Contrary to popular belief, acne isn't caused by diet or hygiene, nor just youth. It can be hereditary. Acne isn't infectious, so you can't catch it.

The processes that cause acne are exactly the same in people with all skin colours. But the impact of acne can be worse if you have darker skin.

Acne typically causes one or more of the following symptoms:

• Greasy skin
• Blackheads (open comedones)
• Whiteheads (closed comedones)
• Red or yellow spots (pustules)
• Deep inflamed lesions (nodules and cysts)
• Scars

Complications of acne: There are a number of things that can make your acne worse. These include -

• If you pick and squeeze the spots, it may cause further inflammation and scarring.
• Excessive production of male hormones may cause acne. For example, testosterone from conditions such as polycystic ovary syndrome.
• Some contraceptive pills may make acne worse. This is due to the type of progestogen hormone in some pills. However, some other types of contraceptive pills can improve acne (see Treatments). Ask your GP for advice about which contraceptive pill to take.
• Some cosmetic products such as moisturisers can make acne worse if they are greasy.
• Some medicines can make acne worse. These include some epilepsy medicines and steroid creams and ointments that are used for eczema. Don't stop a prescribed medicine if you suspect it is making your acne worse, but tell your GP. He or she may be able to recommend an alternative medicine.
• Steroids can cause acne as a side-effect.

Causes of acne: Acne is caused by overactivity of the sebaceous glands that secrete oily substances on to your skin.

Smooth and supple

The surface of your skin has lots of small sebaceous glands just below the surface. These glands make sebum (a natural oil) that keeps the skin smooth and supple.

Tiny pores (holes in the skin) allow the sebum to come to the surface of your skin. Hairs also grow through these pores.

The sebaceous glands of people with acne are especially sensitive to normal blood levels of a hormone called testosterone, found naturally in both men and women.

If you are prone to acne, testosterone triggers the sebaceous glands to produce excess sebum.

The combination of these two effects causes a build-up of oil in your hair follicles. This causes blackheads and whiteheads to form. For some people, their acne doesn't progress beyond this stage.

However, in other people the build-up of oil in the hair follicles creates an ideal environment for a bacterium called Propionibacterium acne to grow.

These bacteria usually live harmlessly on your skin but when the conditions are right, they grow. They feed off the sebum and produce substances that cause an immune response. This inflames the skin and creates the redness associated with spots.

In more severe inflammatory acne, cysts develop beneath the skin's surface. If these cysts rupture, the infection can spread. This can result in scars.

acne isn't infectious, so you can't catch it.

Treating acne

A range of treatment options will help treat acne. As acne can't be cured, treatments aim to control the symptoms by:

• Preventing new spots forming
• Improving those already present
• Preventing scarring

It's important to keep spot-prone areas clean, so wash the affected area twice a day with an unperfumed cleanser. Mild skin peels and microdermabrasion will exfoliate and keep the pores from becoming blocked.

A number of over-the-counter remedies are available from pharmacies to treat mild acne. These usually contain antibacterial agents such as benzoyl peroxide.

Benzoyl peroxide can cause redness and peeling, especially to start with. This tends to settle down if you reduce the number of times you use it. You can then build up your use gradually.

Home treatments for acne won't work immediately. It can take weeks, sometimes months, for significant effects to be noticeable. If home treatments haven't worked after two months, or you have severe acne, you should visit your GP.

Links:
Introduction to acne
Acne - article 3
What does it cost?