Acne, like angst and a preference for loud music, is all but a rite of passage for most teenagers.

That's unsurprising: More than 75 per cent of teenagers in Singapore develop acne, said Assistant Professor Wong Soon Tee, consultant dermatologist and physician at Raffles Hospital.

Teens' hormonal surge during puberty causes acne to erupt.

But adults are not immune. Dr Chris Foo, consultant dermatologist at Raffles Hospital, said: 'Acne can persist even into adulthood. I have seen adults in their 30s and 40s still struggling with acne.'

It results from overproduction of the body's oil called sebum, inflammation of clogged pores by bacteria and abnormal shedding of dead skin cells.

Just below the skin surface is the pilosebaceous unit, comprising hair follicles and the sebaceous gland.

Hair follicles conduct sebum out of the skin, providing it with moisture.

But when there is increased oil production or slower removal of excess oil due to narrowing of the sebaceous gland's lining, the oil is trapped and accumulates there.

This allows the bacteria, Propionibacterium acnes, to thrive there, especially now that there is less oxygen since the hair follicles are plugged with dead skin cells.

Also, the trapped oil becomes food for the bacteria, which further multiply while excreting an inflammatory by-product. This inflames the sebaceous gland.

The result: the bump or swelling we call acne.

This term refers to not just pimples and pustules - which are pus-filled pimples - but also whiteheads and blackheads.

Acne can occur on the face, neck, shoulders, chest and back, where the most functional oil glands are found.

Genetics and hormones also play a part. Dr Chee Yew Wen, medical director of Wen & Weng Medical Group, said: 'Males tend to get more severe teenage acne but females are more prone to adult acne probably due to hormonal cycles.'

Acne in teenagers tends to occur on the T-zone - the area sweeping from the forehead down to the chin - and cheeks, while acne in adults tends to occur around the mouth and jawline.

On the effect of the hot and humid climate in Singapore, Dr Foo said: 'It may be a factor because it can lead to increased sweating and oil build-up on the skin which are risk factors for developing acne.'

The condition can be classified into four stages, from mild to severe, but it does not mean there is a linear progression.

Dr Wong said: 'For some patients, acne come on with a bang while others may forever have only blackheads or whiteheads.'

Acne can leave blemishes which fade with time or permanent skin irregularities like raised or deep, pitted scars. Such scars are formed when the body produces fibrous tissue in the skin as a healing response and this tissue contracts as skin heals, pulling the skin downwards.

Dr Leow Yung Hian, senior consultant dermatologist at the National Skin Centre, said that scarring is the end result of inflammatory acne.

Asked if facials will work in treating acne, Dr Derrick Aw, consultant dermatologist at National University Hospital, said: 'Some facials do help with acne, especially those with fruit acids.

'But sometimes beauticians are not qualified to identify what can or can't be extracted from your skin.'

Dr Wong added: 'Taking action against acne early prevents scarring. Prevention is better than cure.'

Furthermore, Dr Chee said, no treatment can completely reduce scars. 'We aim for an improvement of 50 to 60 per cent,' he said.

Treatment acts on the active lesions to prevent them from reforming and repairs the scars on the skin.

Topical treatments like benzoyl peroxide and retinol solutions or antibiotic solutions like clindamycin are effective in reducing sebum secretion and increasing cell turnover, thereby treating and preventing acne outbreaks.

Oral medication like antibiotics and oral contraceptives also help.

The drug Roacutane, also known as isotretinoin, is prescribed to patients with moderately severe acne. However, the drug can cause side effects like dry lips and hair, foetal abnormalities in pregnant women and increased cholesterol.

There is now a drug-free alternative. National University Hospital and some private clinics are using a new machine which uses a specific blue light which acts to destroy the acne-causing bacteria.

Dr Aw said: 'It's suitable for people who have bad acne but can't tolerate the antibiotic treatments or for women with bad acne who want to get pregnant.'

Aesthetic treatments like microdermabrasion, intense pulsed light (IPL) and laser therapies can also help to treat acne and improve the appearance of scars.

For example, IPL kills the bacteria, removes hair and shrinks the inflamed oil gland.

Dr Chee said: 'When the density of facial hair and the activity of the sebaceous gland are reduced, there is less blockage of the pores.

'IPL also helps to repair the red marks and mild acne scars by stimulating collagen growth.'

Doctors whom Mind Your Body spoke to said they tailor treatment according to individuals, depending on the severity of the acne and how quickly they want it cleared up.

Dr Foo said that there is an increasing awareness that acne should be treated aggressively in order to prevent scarring and that it is not just part and parcel of growing up.

'Acne can affect self esteem and also social relationships, especially in this day and age where image is so important,' he added.

Ms Danielle Chen, 27, said her dermatologist prescribed a range of topical treatments to control her acne.

'I feel better about my complexion now. I used to be very upset about my appearance as people would look and wonder what happened to my face,' she said.

She is not alone. Last year, the National Skin Centre treated more than 9,000 patients with acne.

Doctors told Mind Your Body that they see an average of 50 patients with acne a week. Dr Aw summed it up: 'Acne is the bread and butter of dermatologists.'

This article was first published in Mind Your Body, The Straits Times on Aug 6, 2008.