Acne vulgaris

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 unclear¹ . It is a skin commensural but in acne it colonises the follicles² .

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.

Epidemiology²

• Acne is one of the most common skin conditions in the UK leading to 3.5 million visits to primary care every year.

• Western industrialised countries have much higher rates of acne than some non-industrialised countries.

• Up to 95% of adolescents in Western industrialised countries are affected by acne. 20-35% develop moderate or severe acne.

• Of people with acne:

  • 85% are aged 12-24 years.

  • 8% are aged 25-34 years.

  • 3% are aged 35-44 years.

• Acne is more common in males during adolescence. In adulthood, the incidence is higher in women.

Acne may be associated with polycystic ovary syndrome. Acne may result from abnormal production of androgens. This may occur in testosterone replacement therapy, in abuse of anabolic steroids, in Cushing's syndrome or in virilising tumours in women, such as arrhenoblastoma.

Presentation³

• 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 conglobata is a severe form of nodulo-cystic acne with interconnecting sinuses and abscesses. Acne fulminans is a very serious form of acne conglobata associated with systemic symptoms.See the separate Acne Conglobata and Rarer Forms of Acne article.

Differential diagnosis²

• 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.

• Drug-induced acne - eg, corticosteroids, phenytoin, carbamazepine, lithium, isoniazid, vitamins B1, B6 and B12.

• Pityrosporum folliculitis: predominates on the trunk.

Investigations²

• 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.
  

Management⁴

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 hygiene¹ .

A Cochrane review found some low-quality evidence from single trials that low-glycaemic-load diet, tea tree oil, and bee venom may reduce total skin lesions, but there was a lack of evidence to support the use of other complementary and alternative medicines, such as herbal medicine, acupuncture, or wet-cupping therapy⁵ .

There is little evidence concerning the efficacy or lack of efficacy of exposure to sunlight. High-quality evidence on the use of light therapies for people with acne is lacking. There is low certainty of the usefulness of methyl aminolevulinate-photodynamic therapy (red light) or aminolevulinic acid-photodynamic therapy (blue light) as standard therapies for people with moderate to severe acne⁶ .

There is insufficient evidence to support any specific diets for treating acne.

Referral to specialist care

Urgently refer people with acne fulminans on the same day to the on-call hospital dermatology team, to be assessed within 24 hours.

Refer people to a consultant dermatologist-led team if any of the following apply:

• Diagnostic uncertainty.

• Acne conglobata.

• Nodulo-cystic acne.

Consider referring people to a consultant dermatologist-led team if they have:

• Mild to moderate acne that has not responded to two completed courses of treatment.

• Moderate to severe acne which has not responded to previous treatment that contains an oral antibiotic.

• Acne with scarring.

• Acne with persistent pigmentary changes.

Consider referring people to a consultant dermatologist-led team if their acne of any severity, or acne-related scarring, is causing or contributing to persistent psychological distress or a mental health disorder.

Consider referral to mental health services if a person with acne experiences significant psychological distress or a mental health disorder, including those with a current or past history of:

• Suicidal ideation or self-harm.

• Severe depressive or anxiety disorder.

• Body dysmorphic disorder.

Skincare advice

• Non-alkaline (skin pH neutral or slightly acidic) synthetic detergent (syndet) cleansing product twice daily on acne-prone skin.

• If use skincare products (eg, moisturisers, make-up or sunscreens), avoid oil-based products (which are likely to block skin pores). Remove make-up at the end of the day.

• Avoid persistent picking or scratching of acne lesions, which can increase the risk of scarring.

National Institute for Health and Care Excellence (NICE) recommendations

Always emphasise the importance of completing the course of treatment, because positive effects can take 6-8 weeks to become noticeable.

First-line treatment options
A 12-week course of one of the following first-line treatment options:

• Any severity:

  • Topical adapalene with topical benzoyl peroxide.

  • Topical tretinoin with topical clindamycin.

• Mild to moderate acne:

  • Topical benzoyl peroxide with topical clindamycin.

• Moderate to severe acne:

  • Topical adapalene with topical benzoyl peroxide, together with either oral lymecycline or oral doxycycline.

  • Topical azelaic acid with either oral lymecycline or oral doxycycline.

• For people with moderate to severe acne who cannot tolerate or have contra-indications to oral lymecycline or oral doxycycline, consider replacing with trimethoprim or an oral macrolide (eg, erythromycin).

Consider topical benzoyl peroxide monotherapy as an alternative treatment if the above treatments are contra-indicated, or the person wishes to avoid using a topical retinoid, or an antibiotic (topical or oral).

To reduce the risk of skin irritation associated with topical treatments, such as benzoyl peroxide or retinoids, start with alternate-day or short-contact application (for example, washing off after an hour). If tolerated, progress to using a standard application.

Topical retinoids and oral tetracyclines are contra-indicated during pregnancy. Therefore effective contraception is essential, or an using alternative treatment.

If a person receiving treatment for acne wishes to use hormonal contraception, consider using the combined oral contraceptive pill in preference to the progestogen-only pill.

Oral isotretinoin should not be used unless adequate courses of standard therapy with systemic antibiotics and topical therapy have been tried and take this into account when choosing any initial treatment options.

Do not use the following to treat acne: monotherapy with a topical antibiotic, monotherapy with an oral antibiotic, or a combination of a topical antibiotic and an oral antibiotic.

Review
Review first-line treatment at 12 weeks and:

• If treatment includes an oral antibiotic, if their acne has completely cleared consider stopping the antibiotic but continuing the topical treatment.

• In people whose treatment includes an oral antibiotic, if their acne has improved but not completely cleared, consider continuing the oral antibiotic, alongside the topical treatment, for up to 12 more weeks.

Only continue a treatment option that includes an antibiotic (topical or oral) for more than six months in exceptional circumstances. Review at three-monthly intervals, and stop the antibiotic as soon as possible. Be aware that the use of antibiotic treatments is associated with a risk of antimicrobial resistance

If a person's acne has cleared, consider maintenance options.

If acne fails to respond adequately to a 12-week course of a first-line treatment option and at review the severity is:

• Mild to moderate: offer another option from the table of treatment choices.

• Moderate to severe, and the treatment did not include an oral antibiotic: offer another option which includes an oral antibiotic from the table of treatment choices.

• Moderate to severe, and the treatment included an oral antibiotic: consider referral to a consultant dermatologist-led team.

If mild to moderate acne fails to respond adequately to two different 12-week courses of treatment options, consider referral to a consultant dermatologist-led team.

Oral isotretinoin treatment
Consider oral isotretinoin for people older than 12 years who have a severe form of acne that is resistant to adequate courses of standard therapy with systemic antibiotics and topical therapy - eg, nodulo-cystic acne, acne conglobata, acne fulminans, or acne at risk of permanent scarring.

When considering oral isotretinoin for acne take into account the person's psychological well-being, and refer them to mental health services before starting treatment if appropriate.
Isotretinoin can cause serious harm to a developing baby if taken during pregnancy.

When giving isotretinoin as a course of treatment for acne review their psychological well-being during treatment, and monitor them for symptoms or signs of depression. Advise on the importance of seeking help if they feel their mental health is affected or is worsening.

A 2017 meta-analysis revealed no increased risk of depression while on isotretinoin and an improvement in depressive symptoms after treatment, although rare cases of mood exacerbation have been reported in patients who are clinically unstable⁷ .

If an acne flare (acute significant worsening of acne) occurs after starting oral isotretinoin, consider adding a course of oral prednisolone. When a person with acne fulminans is started on oral isotretinoin, consider adding a course of oral prednisolone to prevent an acne flare.

Photodynamic therapy
Consider photodynamic therapy for people aged 18 and over with moderate to severe acne if other treatments are ineffective, not tolerated or contra-indicated.

Intralesional corticosteroids
Severe inflammatory cysts may be treated with intralesional injection of triamcinolone acetonide. This should be done by a member of a consultant dermatologist-led team. In June 2021 this was an off-label use for triamcinolone acetonide.

Treatment options for people with polycystic ovary syndrome

• Treat acne using a first-line treatment option.

• If the chosen first-line treatment is not effective, consider adding ethinylestradiol with cyproterone acetate (co-cyprindiol) or an alternative combined oral contraceptive pill.

• Consider referring people with acne and polycystic ovary syndrome with additional features of hyperandrogenism to an appropriate specialist - eg, a reproductive endocrinologist.

Relapse

• If acne responds adequately to a course of an appropriate first-line treatment but then relapses, consider either another 12-week course of the same treatment, or an alternative 12-week treatment.

• If acne relapses after an adequate response to oral isotretinoin and is currently mild to moderate, offer an appropriate treatment option. If acne relapses after an adequate response to oral isotretinoin and is currently moderate to severe, offer a 12-week course of an appropriate treatment option.

• If acne relapses after a second course of oral isotretinoin and is currently moderate to severe, further care should be decided by the consultant dermatologist-led team.

Maintenance

• Encourage continued appropriate skin care.

• Maintenance treatment is not always necessary. Consider maintenance treatment in people with a history of frequent relapse after treatment.

• Consider a combination of topical adapalene and topical benzoyl peroxide as maintenance treatment. If this is not tolerated, or if one component of the combination is contra-indicated, consider topical monotherapy with adapalene, azelaic acid,or benzoyl peroxide.

• Review maintenance treatments for acne after 12 weeks to decide if they should continue.

Management of acne-related scarring⁸
Early treatment of active acne remains the best way to prevent or limit acne-related scarring. Treatment options for acne scarring include various forms of laser treatment, dermabrasion, chemical peels, micro-needling, radiofrequency, fillers, punch excision and punch elevation, and subcision.

NICE recommends:

• If a person's acne-related scarring is severe and persists a year after their acne has cleared, refer to a consultant dermatologist-led team with expertise in scarring management.

• CO₂ laser treatment (alone or after a session of punch elevation), or glycolic acid peel may be considered.

Infantile acne⁹

• 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.

Complications^{2 10}

Potential sequelae of acne, such as scarring, dyspigmentation, and low self-esteem, may result in significant morbidity.

• 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.

  • The risk of scarring increases with the severity and duration of acne.

• 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.

Prognosis²

Acne can persist for many years. It tends to affect adolescents and usually resolves after the end of growth. However, it may persist into adulthood, either as a continuation of adolescent acne or due to development of late-onset disease.