What is acne and what causes it?

Acne is a common condition affecting 90% of teenagers to some degree, particularly around puberty. It usually lasts about 5 years but in some people it can persist for many years.

During adolescence, there is an increase in the production of oil (sebum) in the skin which makes the skin greasier. If your skin pores get blocked, there is a collection of sebum and dead skin cells, causing a ‘spot’. These can appear as blackheads (the spot appears to have a black head) or whiteheads (these can often be felt under the skin and may be seen better when the skin is stretched as white spots). If these get inflamed or infected with a bacterium called P.acnes, then the spot becomes red and angry.

Therefore the appearance and severity of acne can vary considerably between individuals and your treatment will be tailored to the type of acne you suffer from.


The aim is to clear the majority of spots without any scarring of the skin and to prevent new spots from emerging. It takes time for acne to clear and it may take 8-12 weeks to see an improvement. It is important to continue using acne creams such as benzoyl peroxide or retinoids to maintain clear skin.

Skin care in acne prone skin

Wash the skin gently with a mild soap and lukewarm water. Do not rub vigourously or use exfoliating agents like face washes with granules. Excessive scrubbing may provoke further inflammation in the skin.

Use a light moisturiser and if the acne creams dry out your skin, then try and use a fragrance-free, water-based moisturiser. Do not use oily moisturisers.

Acne creams

These should be applied to the whole affected area of the face and not to individual spots. This is to prevent new spots from developing in the acne-prone sites.

There are lots of different types of acne creams and lotions. They are usually agents which dry out the skin and reduce inflammation and are sometimes found in combination with an antibiotic.

Benzoyl Peroxide cream
This can be bought from a pharmacy and comes in different strengths (2.5%, 5%, 10%). It works to reduce blackheads and whiteheads and also reduces inflammation in the skin as well as killing bacteria.

Use the lowest strength first as this causes the least skin irritation. Work up the strength gradually. Wash your face and apply the cream 30 minutes thereafter. Apply it once a day at first and then twice a day when your skin is used to it.

It may bleach bed linen/towels that come into contact with it.

Retinoid gels (Adapalene, Tretinoin, Isotretinoin)
They are good at unplugging pores and treating blackheads and whiteheads and mildly inflamed acne. They are usually the treatment of choice for maintaining clear skin even after courses of tablets by mouth.

The skin may go red and feel irritated and peel initially which settles over time. Your skin may become more sensitive in the sunlight, so apply the creams at night and wash off in the morning. Apply sun-protection cream during the day as required.

If the side effects do not settle, apply it less frequently and leave it on the skin for a shorter duration.

These are not to be used if you are pregnant or are planning a pregnancy. Please discuss contraception with your doctor.

Topical antibiotics
These reduce inflammation as well as bacteria numbers. They do not unplug pores and so are often found in combination with one or the other of the above 2 types of creams. These are used when your spots are inflamed- red and angry.

Tablets for acne

These kill bacteria and reduce inflammation. They do not unplug pores so should be used in combination with benzoyl peroxide or a retinoid cream. They must be used for a minimum of 3 months before you can tell whether they are effective or not.

The tetracycline group of antibiotics is most commonly used. These include oxytetracyline , which should be taken on an empty stomach and doxycyline, lymecycline and minocylcine which can all be taken on a full stomach.

These are not to be taken if you are intending to become pregnant, are pregnant or breastfeeding. Please talk to your doctor about contraception whilst taking these. They should not be used in children under 12 years of age.

Other antibiotics used in acne are erythromycin and trimethoprim and may be chosen if tetracyclines are unsuitable.

The Combined Contraceptive Pill
Dianette may be helpful in women where there is an acne flare around their periods. It is also useful when there is excessive facial hair growth in addition to acne. Yasmin, another contraceptive pill, is also sometimes used.

Isotretinoin tablets
This agent reduces the amount of sebum (oil) produced and dries out the skin. It is extremely effective even in severe cases. It is usually prescribed by a specialist when other treatments have failed as there is a risk of serious side effects associated with it, which will need careful monitoring. It is very important that you are not pregnant or fall pregnant whilst on this medication.

How to maintain clear skin

Acne treatment works well if used properly and for long enough periods. It is very important to use a retinoid cream or benzoyl peroxide gel as maintenance to keep acne from returning. These are safe to use indefinitely, even for years.


Patient UK

British Association of Dermatologists

Primary Care Dermatology Society

NZ Derm Net