Professional Reference articles are written by UK doctors and are based on research evidence, UK and European Guidelines. They are designed for health professionals to use, so you may find the language more technical than the condition leaflets.
Acne vulgaris is a disorder of the pilosebaceous follicles found in the face and upper trunk. At puberty androgens increase the production of sebum from enlarged sebaceous glands that become blocked. Propionibacterium acnes is involved in lesion production although its exact role is unclear.It is a skin commensural but in acne it colonises the follicles.
Comedones (follicles impacted and distended by incompletely desquamated keratinocytes and sebum) may be open (blackheads) or closed (whiteheads). Inflammation leads to papules, pustules and nodules.
Acne can cause severe psychological problems, undermining self-assurance and self-esteem at a vulnerable time in life.
- Almost every teenager can expect to experience acne to some degree during the adolescent years although it is usually mild. Moderate-to-severe acne affects about 20% of young people.
- Genetic factors play a part and a positive family history is often a factor; concordance among twins has been demonstrated. The heritability is almost 80% in first-degree relatives. A positive family history is linked to earlier and more severe acne.
- Acne tends to affect boys more than girls.
- Acne tends to occur in adolescence, when hormones are in a state of flux. Since puberty is starting earlier, acne is being seen in younger patients.
- In girls it may flare up when they are premenstrual.
- Acne may be associated with polycystic ovary syndrome.
- Acne may result from abnormal production of androgens. This may occur in testosterone replacement therapy, abuse of anabolic steroids, Cushing's disease or in virilising tumours in women, such as arrhenoblastoma.
- Acne usually presents with a greasy skin with a mixture of comedones, papules and pustules, which present just after puberty and continue for a variable number of years, usually stopping in late teens or early 20s but uncommonly continuing well into adulthood.
- The face is affected in 99% of cases, the back in 60% and the chest in 15%.
- Acne runs a variable course with marked fluctuations.
- Nodulocystic acne: severe acne with cysts. Cysts can be painful. They may occur in isolation or be widespread over the face, neck, scalp, back, chest and shoulders.
- The severity of the condition varies enormously between individuals. It is unsightly but the degree of distress is sometimes disproportionate.
- Acne rosacea: usually presents in middle age or later in life.
- Folliculitis and boils: may present with pustular lesions similar to those seen in acne.
- Milia: small keratin cysts that may be confused with whiteheads. They tend to be whiter than acne whiteheads and are most commonly seen around the eyes.
- Perioral dermatitis.
- Pityrosporum folliculitis: predominates on the trunk.
- Usually no investigations are required.
- Investigations are occasionally required to explore a possible underlying cause - eg, virilising tumour.
- Skin lesion culture may be warranted in patients who do not respond to treatment, to exclude Gram-negative folliculitis.
Severe acne is a serious disease in that it is disfiguring, has enormous psychological impact and requires referral to a dermatologist.
- Usually acne is a mild and self-limiting condition but teenagers are very sensitive about it and so it is essential to be empathetic as well as providing advice and reassurance.
- Patients are traditionally advised to keep the face clean, although there is no convincing evidence linking acne with poor hygiene.
- A Cochrane review found some low-quality evidence from single trials that low glycaemic load diets may reduce total skin lesions. This was considered insufficient evidence to recommend dietary manipulation as a general measure. Likewise, similar low-quality evidence was found for the effectiveness of tea tree oil and bee venom.There is little evidence concerning the efficacy or lack of efficacy of exposure to sunlight.
- Use of the 1450-nm laser promotes improvement in acne. Interestingly, this improvement is seen bilaterally in studies in which only one side of the face is treated, suggesting a systemic effect.
- Blue light phototherapy can be useful for mild-to-moderate papulopustular acne.
- Many men who suffer significant acne into adult life choose to grow a beard to hide it.
- Topical treatments need to be applied to all affected areas and not just to existing lesions. They are difficult to apply to the back and so widespread acne requires systemic treatment.
- Salicylic acid 10% has a keratolytic effect on comedones but is considered less effective than topical retinoids.
- Azelaic acid is least irritating but it can cause hypopigmentation.
- For mild papulopustular acne, benzoyl peroxide reduces sebum production and comedones and inhibits the growth of P. acnes:
- It is mildly irritant and causes peeling after a few days.
- Start with 5% used sparingly; increase usage and/or concentration to 10% later.
- It tends to produce a burning sensation on the skin after application, especially if it is greasy.
- Benzoyl peroxide can be combined with topical clindamycin or erythromycin in gel preparations.
- Topical antibiotics:
- Topical antibiotics can be effective. Erythromycin, clindamycin and tetracycline are the ones most commonly prescribed but there is no evidence to suggest that any particular topical antibiotic is better than any other.
- Monotherapy should be strongly discouraged. Antibiotic resistance can be reduced and effectiveness increased by combining with a topical retinoid or benzoyl peroxide.
- Topical antibiotics should be prescribed for no more than 12 weeks where possible.
- Topical retinoids:
- Local treatment with isotretinoin, tretinoin or adapalene reduces comedones and has an anti-inflammatory effect.
- Avoid exposure to strong sunlight, which causes irritation that is greatest after a few weeks of treatment. The irritation can be treated with moisturisers. Adapalene is the least irritant.
- Systemic absorption is minimal but topical retinoids are still contra-indicated in pregnancy.
- Any systemic treatment often takes several months to show any improvement and should therefore be continued for 3-4 months, if tolerated, before effectiveness can be properly assessed.
- Systemic treatment may be combined with topical treatment.
- People with dark skin often need early systemic treatment because they can develop severe post-inflammatory pigmentation.
- Having reviewed the available literature, the European Dermatology Forum has concluded that no particular oral antibiotic demonstrates superiority with respect to efficacy, tolerability or safety.
- Antibiotics are thought to have an anti-inflammatory as well as anti-infective action.
- The most frequent adverse reactions for doxycycline are photosensitivity and oesophagitis but these are usually manageable. The safety profile of lymecycline is comparable to that of tetracycline. Doxycycline and lymecycline are generally preferred to tetracycline because they require less frequent administration. Clindamycin is normally reserved for severe infections. Minocycline is no longer recommended.
- Oral antibiotics have always been held to be more efficacious than topical antibiotics for mild-to-moderate papulopustular acne. However, the evidence base supporting this belief is equivocal. Topical benzoyl peroxide and benzoyl peroxide/erythromycin combinations are similar in efficacy to oral oxytetracycline and are not affected by propionibacterial antibiotic resistance. Oral antibiotics are more appropriate if the lesions are widespread. They also demonstrate superiority in moderate-to-severe papulopustular acne.
- Anti-androgen treatment:
- A standard oral contraceptive is an effective treatment for acne.
- A combination of 50 micrograms of ethinylestradiol with the anti-androgen cyproterone is available as co-cyprindiol (Dianette®). It has a 1.5-2 times greater risk of causing deep vein thrombosis than oral contraceptives and is only recommended when other treatments fail. It is an effective contraceptive but is not licensed as such and the patient must be told this. It should be stopped 4 or 5 menstrual cycles after the acne has resolved.
- Oral isotretinoin:[9, 10]
- The retinoid isotretinoin reduces sebum secretion.
- It is highly effective but toxicity problems confine its use to hospitals and under consultant supervision.
- Dry skin, lips and eyes are common. Raised serum lipids occur in a third of patients. Muscle aches and pains on strenuous exercise, hair thinning and acne flare-up also occur.
- The main problem is teratogenicity that continues to damage the fetus after discontinuation. Effective contraception is therefore essential in female patients, continued for one month after stopping treatment.
- Isotretinoin has had some causes for concern in that it has been associated with a variety of adverse psychiatric effects, including depression, psychosis, mood swings, violent behaviour, suicide and suicide attempts. However, a review of the evidence concluded that there is insufficient evidence to conclude a causal relationship between isotretinoin and psychiatric adverse events.
- Treatment for scarring:
- Laser resurfacing, dermabrasion and chemical peels are used in the treatment of acne scarring.
- Microdermabrasion is a simple outpatient procedure in which aluminum oxide crystals or other abrasive substances are blown on to the face and then vacuumed off, using a single handpiece. It has a limited role in the management of acne scars.
- Subcision is occasionally used to treat depressed acne scars. It involves inserting a tri-beveled hypodermic needle through a puncture in the skin surface and manoeuvering its edges to break down subcuticular fibrotic strands, thus releasing the skin from the underlying connective tissue.It appears to be equal in efficacy to collagen filler..
The following guidelines should be:
- People who have severe psychological problems (including body dysmorphic disorder) should be referred to a psychiatrist.
- Routine referral to a dermatologist should be made for:
- People who have developed, or are at risk of, scarring despite treatment in primary care.
- People who have moderate acne which has persisted after six months of treatment in primary care, or treatment failure in concordance with the patient's wishes.
- People in whom the diagnosis is uncertain.
- Referral should be made to an endocrinologist or gynaecologist if an endocrine cause is suspected (eg, polycystic ovary disease).
- An urgent referral should be made for people with a severe variant of acne with systemic symptoms (such as acne fulminans).
- Other people with severe acne should be referred for a 'soon' appointment, including people with painful, deep nodules or cysts (nodulocystic acne).
- Acne - even severe acne - can occur in infants and neonates.
- Infantile acne is rare. It is more common in boys.
- It most often presents as comedones, papules and pustules on the cheeks at 3-6 months of age.
- Treatment for mild acne is topical antiseptics and antibiotics. Low-strength topical retinoids may be used to treat comedones.
- Severe acne requires systemic antibiotics (tetracyclines must be avoided).
- Severe cystic acne can be treated with oral isotretinoin.
- Infantile acne usually disappears within one or two years but may persist to puberty.
- Acne causes a significant psychological and social morbidity, with anxiety, severe depression and suicidal ideation.There can be a serious lack of self-esteem leading to social isolation. Bullying and stigmatisation can occur. Young people have been reported to have the same psychological difficulties as those with more serious diseases such as asthma and diabetes.
- Any form of acne can lead to permanent scarring. Scarring usually results from deep lesions but superficial lesions can also cause scarring. Scarring is usually atrophic and hypertrophic or keloid scarring occurs less often. One person in five gets significant (ie socially obvious) scarring.
- Post-inflammatory hyperpigmentation may occur, especially in people with darker skin.
- Gram-negative folliculitis may occur as a complication of long-term oral erythromycin or tetracycline treatment. Treatment with trimethoprim may be effective.
Most cases clear up spontaneously with less than 12% of women and 3% of men being affected after the age of 25.
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Further reading & references
- Acne Vulgaris; DermIS (Dermatology Information System)
- Simpson RC, Grindlay DJ, Williams HC; What's new in acne? An analysis of systematic reviews and clinically significant Clin Exp Dermatol. 2011 Dec 36(8):840-3
- Schnopp C, Mempel M; Acne vulgaris in children and adolescents. Minerva Pediatr. 2011 Aug 63(4):293-304.
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