Acne is an inflammatory disease of the skin, caused by changes in the pilosebaceous units (skin structures consisting of a hair follicle and its associated sebaceous gland).

The condition is common in puberty as a result of an abnormal response to normal levels of the male hormone testosterone. The response for most people diminishes over time and acne thus tends to disappear, or at least decrease, after one reaches their early twenties. There is, however, no way to predict how long it will take for it to disappear entirely, and some individuals will continue to suffer from acne decades later, into their thirties and forties and even beyond. Acne affects a large percentage of humans at some stage in life.

The term acne comes from a corruption of the Greek О¬ОєОјО® (acme in the sense of a skin eruption) in the writings of AГ«tius Amidenus.

Symptoms

The most common form of acne is known as "acne vulgaris", which means common acne. Excessive secretion of oils from the glands combines with naturally occurring dead skin cells to block the hair follicles. Oil secretions build up beneath the blocked pore, providing a perfect environment for the skin bacteria Propionibacterium acnes to multiply uncontrolled. In response, the skin inflames, producing the visible lesion. The face, chest, back, shoulders and upper arms are especially affected.

The typical acne lesions are: comedones, papules, pustules, nodules and inflammatory cysts. These are the more inflamed form of pus-filled or reddish bumps, even boil-like tender swellings. Non-inflamed 'sebaceous cysts', more properly called epidermoid cysts, occur either in association with acne or alone but are not a constant feature. After resolution of acne lesions, prominent unsightly scars may remain.

Aside from scarring its main effects are psychological, such as reduced self-esteem and depression. Acne usually appears during adolescence, when people already tend to be most socially insecure.

Causes of acne

Exactly why some people get acne and some do not is not fully known. It is known to be partly hereditary. Several factors are known to be linked to acne:

• Hormonal activity, such as menstrual cycles
• Stress, through increased output of hormones from the adrenal (stress) glands
• Hyperactive sebaceous glands, secondary to the three hormone sources above
• Accumulation of dead skin cells
• Bacteria in the pores, to which the body becomes 'allergic'
• Skin irritation or scratching of any sort will activate inflammation
• Anabolic steroids - the body-building steroids
• Any medication containing halogens (iodides, chlorides, bromides), lithium, barbiturates, or androgens
• Exposure to high levels of chlorine compounds, particularly chlorinated dioxins, can cause severe, long-lasting acne, known as Chloracne

Traditionally, attention has focused mostly on hormone-driven over-production of sebum as the main contributing factor of acne. More recently, more attention has been given to narrowing of the follicle channel as a second main contributing factor. Abnormal shedding of the cells lining the follicle, abnormal cell binding ("hyperkeratinization") within the follicle, and water retention in the skin (swelling the skin and so pressing the follicles shut) have all been put forward as mechanisms involved.

Several hormones have been linked to acne: the male hormones testosterone, dihydrotestosterone (DHT) and dehydroepiandrosterone sulfate (DHEAS), as well as insulin-like growth factor 1 (IGF-I). In addition, acne-prone skin has been shown to be insulin resistant.

Misconceptions about causes

There are many misconceptions and rumours about what causes the condition:

• Diet. Chocolate, potato chips and sugar, among others, have not been shown to affect acne. This means that the scientific studies done to date did not find a statistically significant difference between acne in two groups of people, one group eating the food in question and one group avoiding it. However, one recent study [1], based on a survey of 47,335 women, did find a positive epidemiological association between milk consumption and acne, particularly skimmed. The researchers hypothesize that the association may be caused by hormones (such as bovine IGF-I) present in cow milk; but this has not been definitively shown. Seafood, on the other hand, may contain relatively high levels of iodine, but probably not enough to cause an acne outbreak. Still, people who are prone to acne may want to avoid excessive consumption of foods high in iodine. It has also been suggested that there is a link between a diet high in refined sugars and acne. According to this hypothesis, the startling absence of acne in non-westernized societies could be explained by the low glycemic index of these tribes' diets. [2] Further research is necessary to establish whether a reduced consumption of high-glycemic foods (such as soft drinks, sweets, white bread) can significantly alleviate acne, though consumption of high-glycemic foods should in any case be kept to a minimum, for general health reasons. [3]
• Deficient personal hygiene. Acne is not caused by dirt. This misconception probably comes from the fact that acne involves skin infections. In fact the blockages that cause acne occur deep within the narrow follicle channel, where it is impossible to wash them away. These plugs are formed by the cells and sebum created there by the body. The bacteria involved are the same bacteria that are always present on the skin. It is advisable to clean the skin on a regular basis, but doing so will not prevent acne. Anything beyond very gentle cleansing can actually worsen existing lesions and even encourage new ones by damaging or overdrying skin.
• Sex. Common myths state that either celibacy or masturbation cause acne and, conversely, that sexual intercourse can cure it. There is no scientific evidence suggesting that any of these are factual. It is true, anger and stress, affect hormone levels and thus bodily oil production, which can cause acne.

Treatments

Available treatments

There are many products sold for the treatment of acne, many of them without any scientifically-proven effects. However, a combination of treatments can greatly reduce the amount and severity of acne in many cases. It is highly advisable to ask a dermatologist about the tradeoffs between these treatments for any individual case, especially when considering using any of them in combination. There are a number of treatments that have been proven effective:

• Killing the bacteria that are harbored in the blocked follicles. This is done either by the intake of antibiotics like the "three 'cyclines" (tetracycline, doxycycline and minocycline), or by treating the affected areas externally with bactericidal substances like benzoyl peroxide or erythromycin. However, reducing the P. acnes bacteria will not, in itself, do anything to reduce the oil secretion and abnormal cell behaviour that is the initial cause of the blocked follicles. Additionally the antibiotics are becoming less and less useful as resistant P. acnes is becoming common. Benzoyl Peroxide has the advantage of being a strong oxidiser and does not appear to generate resistance. Acne will generally reappear quite soon after the end of treatment—days later in the case of topical applications, and weeks later in the case of oral antibiotics.

• Reducing the secretion of oils from the glands. This is done by a daily oral intake of vitamin A derivatives like isotretinoin (marketed as Accutane) over a period of a few months. Isotretinoin has been shown to be very effective in treating severe acne and is effective in well over 80% of patients. The drug has a much longer effect than anti-bacterial treatments and will often cure acne for good. The treatment requires close medical supervision by a dermatologist because the drug has many known side effects (which can be severe). About 25% of patients may need a second treatment for another few months to obtain desired results. The most common side effects are dry skin and nosebleed. Reports that it can also permanently damage the liver are unsubstantiated, and routine testing is considered unnecessary by many dermatologists. Some press reports suggest that isotretinoin may cause depression but as of September 2005 there is no agreement in the medical literature as to the risk. The drug also causes birth defects if women become pregnant while taking it or take it while pregnant. For this reason, female patients are required to use two separate forms of birth control or vow abstinence while on the drug. Because of this, the drug is supposed to be given as a last resort after milder treatments have proven insufficient. Very restrictive rules for use will be in force in the USA beginning in 2006. [4] This has occasioned widespread editorial comment. [5]

• Normalizing the follicle cell lifecycle. A group of medications for this are topical retinoids such as tretinoin (brand name Retin-A), adapalene (brand name Differin) and tazarotene (brand name Tazorac). Like isotretinoin, they are related to vitamin A, but they are administered as topicals and generally have much milder side effects. They can, however, cause significant irritation of the skin. The retinoids appear to influence the cell creation and death lifecycle of cells in the follicle lining. This helps prevent the hyperkeratinization of these cells that can create a blockage. Retinol, a form of vitamin A, has similar but milder effects and is used in many over-the-counter moisturizers and other topical products. Effective topical retinoids have been in use over 30 years but are available only on prescription so are not as widely used as the other topical treatments.

• Exfoliating the skin. This can be done either mechanically, using an abrasive cloth or a liquid scrub, or chemically. Common chemical exfoliating agents include salicylic acid and glycolic acid, which encourage the peeling of the top layer of skin to prevent a build-up of dead skin cells which combine with skin oil to block pores. It also helps to unblock already clogged pores. Note that the word "peeling" is not meant in the visible sense of shedding, but rather as the destruction of the top layer of skin cells at the microscopic level. Depending on the type of exfoliation used, some visible flaking is possible. Moisturizers and anti-acne topicals containing chemical exfoliating agents are commonly available over-the-counter.

• Hormonal treatments. In females, acne can be improved with a combined oestrogen/progestogen contraceptive pill. Cyproterone (Diane 35) is particularly effective at reducing androgenic hormone levels and until recently was the best oral contaceptive treatment. It is not available in the USA, but a newer oral contraceptive containing the progestin drospirenone is now available with fewer side effects than Diane 35 / Dianette. Both can be used where blood tests show abnormally high levels of androgens, but are effective even when this is not the case.

• Phototherapy. It has long been known that short term improvement can be achieved with sunlight. However studies have shown that sunlight worsens acne long-term, presumably due to UV damage. More recently, visible light has been successfully employed to treat acne - in particular intense blue light generated by purpose-built fluorescent lighting, LEDs or lasers. Used twice weekly, this has been shown to reduce the number of acne lesions by about 64% [6]; and is even more effective when applied daily. The mechanism appears to be that porphyrins produced by P. acnes generate free radicals when irradiated by blue light. Particularly when applied over several days, these ultimately kill the bacteria [7]. Extensive basic science and clinical work first initiated by dermatologists Yoram Harth and Alan Shalita have shown that intense blue/violet light (405-425 nanometer) can decrease the number of inflammtory acne lesion by 60-70% in 4 weeks of therapy. Since porphyrins are not otherwise present in skin, and no UV light is employed, it appears to be safe, and has been licensed by the U.S. FDA [8]. The treatment apparently works even better if used with red visible light; and overall it has better clearance than benzoyl peroxide. Unlike most of the other treatments few if any negative side effects are typically experienced, and bacterial resistance is unlikely. After treatment, clearance can be longer lived than is typical with topical or oral antibiotic treatments, several months is not uncommon. However, the equipment is relatively expensive, and the treatment works best for mild-moderate acne.

Less widely used treatments include:

• Azelaic acid (brand names Azelex, Finevin, Skinoren) is suitable for mild, comedonal acne. [9]
• Zinc. Orally administered zinc gluconate has been shown to be effective in the treatment of inflammatory acne, although less so than tetracyclines. [10] [11]

• Alternative treatments. Nicholas Perricone's controversial book The Acne Prescription proposes an alternative treatment for adult acne, including a strict diet (dairy is totally avoided in all but two recipes) and topicals containing alpha lipoic acid. Perricone's claims did not seem to be backed up by strong scientific evidence until the publication of the acne / milk link in early 2005. There are no double-blind studies proving the effectiveness of fatty acids against acne.

Popping a pimple or any physical acne treatment should not be attempted by anyone but a qualified dermatologist. Pimple popping irritates skin, can spread the infection deeper into the skin and can cause permanent scarring.

Home remedies: Some people claim that several things in your kitchen like nutmeg, honey, cinnamon, garlic, orange peel, sandalwood, etc can cure your acne. None of these methods have been scientifically proven. One page with such information is [12].

Future treatments

Lasers (surgery?) have been in use for some time to reduce the scars left behind by acne, but research is now being done on lasers for prevention of acne formation itself. The laser is used to produce one of the following effects:

• to burn away the follicle sac from which the hair grows
• to burn away the sebaceous gland which produces the oil
• to induce formation of oxygen in the bacteria, killing them

Since lasers and intense pulsed light sources cause thermal damage to the skin there are concerns that laser or intense pulsed light treatments for acne will induce hyperpigmented macules (spots) or cause long term dryness of the skin. As of 2005, this is still mostly at the stage of medical research rather than established treatment.

Because acne appears to have a significant hereditary link, there is some expectation that cheap whole-genome DNA sequencing may help isolate the body mechanisms involved in acne more precisely, possibly leading to a more satisfactory treatment. (Crudely put, take the DNA of large samples of people with significant acne and of people without, and let a computer search for statistically strong differences in genes between the two groups). However, as of 2005 DNA sequencing is not yet cheap and all this may still be decades off. It is also possible that gene therapy could be used to alter the skin's DNA.

Preferred treatments by types of acne vulgaris

Note: always consult a dermatologist to know what is best for you.

• Comedonal (non-inflammatory) acne: local treatment with azelaic acid, salicylic acid, topical retinoids, benzoyl peroxide.
• Mild papulo-pustular (inflammatory) acne: benzoyl peroxide or topical retinoids, topical antibiotics (such as erythromycin).
• Moderate inflammatory acne: benzoyl peroxide or topical retinoids combined with oral antibiotics (tetracyclines). Isotretinoin is an option.
• Severe inflammatory acne, nodular acne, acne resistant to the above treatments: isotretinoin, or contraceptive pills with cyproterone for females with virilization or drospirenone for any female.

Acne scars

Severe acne often leaves small scars where the skin gets a "volcanic" shape. Acne scars are very hard (and expensive) to treat and it is unusual for the scars to be successfully removed completely. In those cases, scar treatment may be appropriate. The most commonly used forms of scar treatments are:

• Dermabrasion. The top layer of the skin is removed with a high-speed rotary wire brush or diamond-coated fraise (a grinding wheel) to make the scar look less pitted. It makes the scar less visible but does not remove it completely. Multiple treatments may be necessary to get the desired results. This procedure is usually performed by a dermatologist or cosmetic surgeon and is less commonly done now because of the risk of blood-borne diseases.
• Microdermabrasion is a newer technique that has a similar effect to traditional dermabrasion, but is less radical. While dermabrasion is a surgical procedure, microdermabrasion is performed by blasting tiny crystals at the skin or rubbing the skin with a rough tool under suction. Many dermatologists and cosmetic surgeons offer this procedure.
• Laser resurfacing. A laser is used to burn off the top layer of the skin. This procedure is commonly known by the brand names of the machines used to perform it, including SmoothBeam. Many dermatologists and cosmetic surgeons offer this procedure.
• Punch excision. The scar is excised with a punch tool and the edges are sutured together. This procedure is usually performed by a dermatologist or cosmetic surgeon.
• Chemical peels (also known as acid peels). A type of organic acid, most commonly glycolic, salicylic, or lactic, is applied to the skin so that a smoother layer can surface. Despite its unpleasant name, superficial peels are painless if performed properly and require no anaesthetic. Peels are typically performed several times over a period of weeks or months. The procedure can also be beneficial for active acne. Many dermatologists and cosmetologists offer this procedure, although the peels given by dermatologists are generally of a higher concentration and therefore potentially more effective. Deep peels are more aggressive and painful and require significant expertise.
• Subcision. The scar is detached from deeper tissue, allowing a pool of blood to form under the scar which helps form a connective tissue under the scar, levelling it with the surface. This procedure is usually performed by a dermatologist or cosmetic surgeon.
• Dermal filler. The scar is filled with an injectable dermal filler. There are several trade names.

Similar conditions

• Keratosis pilaris is a skin condition that is often confused with acne.

• Rosacea (ro-ZAY-she-ah) sometimes called "Adult Acne" occurs in people of all ages, especially older women when they go through menopause. Two famous men with the affliction are W.C. Fields and former United States President Bill Clinton. The disorder is characterized by redness, pimples, and, in advanced stages, thickened skin. People who suffer from flushing or blush easily are most at risk of developing rosacea.

References

• James, W. D. (2005, April 7). Acne. In The New England Journal of Medicine, 352, 1463 – 1472.
• Webster, G. F. (2002, 31 August). Acne vulgaris. BMJ, 475-479.[13]

External links

• Acne Information - Provides information on what acne is, treatments, and scarring. A little out of date
• Acne Fact Sheets
• Acne vulgaris: more than skin deep (on the psychological effects of acne)
• Acne.org Good overall information, in particular outlines exactly how to use Benzoyl Peroxide correctly and what other treatments work well with it