Acne is a condition of the skin which causes spots, especially on the face, shoulders, and upper back. Acne tends to begin at puberty, and although most sufferers are over it within a few years, it may carry on for life.

Spots form in the glands of the skin that produce protective oils (sebaceous glands). The places where the spots usually occur are the face, shoulders, and upper back.

Acne may result in:

• Small spots known as "blackheads" (open comedones)
• Small spots that are white in colour, known as "whiteheads" (closed comedones)
• These may become infected by a germ or bacterium (Propionibacterium acnes) which makes the spot inflamed, and results in a larger raised spot (papule), a spot filled with pus (pustule), or a hardened lump (nodule)
• The largest spots are more likely to leave lasting scars

Some people are more at risk of developing an obvious or raised scar to any injury or cut. This reaction is known as keloid formation, and in people that have that tendency there is more scarring as a result of acne.

Acne begins with the changes of puberty and is due to the change in hormones. It seems that it is usually a case of the skin over-reacting to the hormone levels, rather than there being particularly high hormone levels in those people who get bad acne.

1. The glands produce too much of their oils (sebum).
2. There are tubes (ducts) that run to the surface of the skin from these glands. Too many of the cells lining the ducts are produced.
3. This leads to tiny plugs blocking the ducts.
4. The glands continue to secrete, leading to swelling behind the plug.
5. The blocked ducts become infected with a germ (Propionibacterium acnes), which leads to inflammation and the production of larger, redder spots, sometimes filled with pus.

Some of these treatments may be obtained direct from the supermarket, but if you have any more than a minor problem you should consult a pharmacist or your doctor. As with all other medications, anything that can have a useful effect is also capable of having unwanted or harmful effects. Read the instructions, and discuss any concerns with your pharmacist or doctor.

Be patient! Treatment may take a few weeks to start having useful effects. The approach should be one of regular use, not just treating a spot when it arrives.

• Washes and scrubs. These are antiseptic liquid cleansers, sometimes similar to the ones surgeons use on their hands before performing an operation. It is thought that these may be helpful, particularly combined with another form of treatment.

• Benzoyl peroxide. This is a chemical which is in many acne preparations. It opens up the blocked ducts, and helps to kill the bacteria. It comes in various strengths, and you should start on the lowest strength you can get (usually 2.5%) because it makes the skin red and raw to begin with when first used. You can work up to 10% strength. Benzoyl peroxide may bleach hair or clothing with which it comes into contact.

• There are other chemicals sometimes used in creams and gels such as: salicylic acid, nicotinamide, and azelaic acid.

• Creams, lotions etc., based on Vitamin A eg tretinoin, isotretinoin, and adapalene. These, as with benzoyl peroxide, irritate the skin. You should start off on a low strength and build up as the skin gets used to it. These preparations can also be used to get rid of wrinkles! These should not be used during pregnancy or breast feeding.

• Preparations to apply to the skin which contain antibiotics (topical antibiotics). There is one of these (containing tetracycline) that shows up on your face when illuminated with ultraviolet light. Beware, if you go to discothèques!

• Antibiotics by mouth can be helpful in more severe cases. Note that caution is needed in starting these if you are on the oral contraceptive pill, also they should not be used in pregnancy or while actively trying to become pregnant. Your doctor will advise.

• There is a hormonal treatment that helps clear acne in some women, and also acts as a contraceptive.

• Tablets based on Vitamin A. ERRORX these may only be prescribed by a skin specialist (dermatologist). These are very effective, also very expensive, and have a number of potential side effects, but for severe cases are thought to be worthwhile.

• Wash regularly, possibly with one of the antiseptic washes.
• Avoid covering yourself with thick layers of make up, and if you do, wash it off as soon as you can, certainly do not leave on overnight.
• Apply any medicinal creams you use regularly to the whole of the affected area.
• Try to resist the temptation to squeeze your spots. This can cause the area to become more inflamed and therefore more likely to scar. It can be dangerous to squeeze spots in the area around the cheek and nose, as infection can be caused to spread to more vital internal structures.

• US NIAMS Acne Q&A
• British Association of Dermatologists Acne information