Acne vulgaris

What is 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, also known as cutibacterium acnes, is involved in lesion production although its exact role is unclear. It is a skin commensal but in acne it colonises the follicles, possibly due to the fact that, during adolescence, the sebaceous glands become hypersensitive to normal circulating volumes of androgens.¹²

Acne vulgaris comprises of:

• Superficial lesions

  • Comedones (follicles impacted and distended by incompletely desquamated keratinocytes and sebum) which may be open (blackheads) or closed (whiteheads). Inflammation leads to papules, pustules and nodules.

  • Papules

  • Pustules

• Deeper lesions

  • Nodules

  • Pseudocysts

Acne can cause severe psychological problems, undermining self-assurance and self-esteem at a vulnerable time in life.

How common is acne vulgaris? (Epidemiology) ¹²

• 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.

• Worldwide, between 35% and 95% of people are thought to become affected by acne vulgaris.³

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

• It is more common in urban than rural areas.

• Although most common in adolescence, it can persist into adulthood or start in adulthood though this is less common.

• Studies suggest that people of Asian or African origin are more likely to develop severe acne whereas mild acne is more common in white people.

• Hyperpigmentation due to acne vulgaris is also more common in darker skin.

• There is a genetic component to acne vulgaris; people with a first degree relative who was affected have a 3 times higher chance of developing acne themselves.

• Specific gene expressions have been found to have an increased incidence in acne.²

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.

Symptoms of acne vulgaris (presentation)²³⁴

• Acne usually presents with a greasier 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, and rarely continuing into adulthood.

• The face is most commonly affected, with the back and chest also relatively commonly affected.

• Acne tends to run a variable course with marked fluctuations.

• 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 diagnosis¹

• 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.

Diagnosing acne vulgaris (investigations)¹

• Usually no investigations are required.

• Investigations are occasionally required to explore a possible underlying cause - eg, virilising tumour.

Management of acne vulgaris⁵

Acne can be divided into mild, moderate and severe categories. Treatment depends on which category the patient falls into. Although most cases are mild and self-limiting, it can still have an impact on self-confidence. Treatment is recommended at any severity.

Severe acne is a serious disease in that it is scarring, disfiguring, has enormous psychological impact and requires referral to a dermatologist.

General management advice

Patients are traditionally advised to keep the face clean, although there is no convincing evidence linking acne with poor hygiene.⁶Gentle cleansers have been shown to be more beneficial than soaps which can increase acne lesions.²

There is variable evidence linking diet to acne. There is some evidence that regular consumption of omega-3 fatty acids reduces the number of acne lesions; there is also evidence that diets lower in sugar and diets lower in milk (though not other dairy products) reduce the number of acne lesions.⁷

There is a lack of evidence to support the use of complementary and alternative medicines, such as herbal medicine, acupuncture, or wet-cupping therapy.⁸

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 acne.⁹

Referral to specialist care

Urgently refer people with acne fulminans ¹⁰on 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:

• Acne conglobata.

• Nodulo-cystic acne.

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

• Acne with scarring.

• Acne with persistent pigmentary changes.

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

Consider referring people to a consultant dermatologist-led team if their acne of any severity 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.

Medical Treatment of acne vulgaris

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

Consider topical benzoyl peroxide monotherapy as an alternative treatment to those below if other treatments are contra-indicated, or the person wishes to avoid using a topical retinoid, or an antibiotic (topical or oral). This can also be bought over the counter. Warn the patient and their family of the risk of bleaching towels, bed linen and clothes unless washed off correctly.

Mild to moderate acne

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

• Topical adapalene with topical benzoyl peroxide.

• Topical tretinoin with topical clindamycin.

• Topical benzoyl peroxide with topical clindamycin.

Moderate to severe acne

• Topical adapalene with topical benzoyl peroxide.

• Topical tretinoin with topical clindamycin.

• Topical azelaic acid with either oral lymecycline 408 mg once a day or oral doxycycline 100 mg once a day.

• A fixed combination of topical adapalene with topical benzoyl peroxide, together with either oral lymecycline 408 mg or oral doxycycline 100 mg once daily.

• 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).

Severe acne

Start treatment with a combination of oral antibiotics and topical treatment whilst awaiting dermatology assessment.

Advice related to medication

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 using an 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.⁴

Oral isotretinoin should not generally 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. In the UK, oral isotretinoin can only be prescribed by consultant dermatologists who need to maintain all follow up of the patient, including liver function tests and mental health assessments.

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: 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 referral for 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 dermatologists are giving isotretinoin as a course of treatment for acne, it is important that they 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 unstable.¹¹

More recent studies suggest that depression and increased suicidality are seen on isotretinoin, though all studies comment on the fact that teenage patients with acne have increased depression before treatment. No causal link has yet been established between isotretinoin and depression. ¹²

Other neuropsychiatric disorders have been reported in patients taking isotretinoin, including mania, violence, aggression, and psychosis, as well as depression and suicide. The author of a recent comprehensive literature review advised that, whilst these effects were not common, particularly in the context of significantly increased numbers of prescriptions for isotretinoin worldwide, they are of concern and that clinicians should consider the benefits of treatment on an individual basis for each patient.¹³

Historically, these side effects have always been reported as stopping once the medication is stopped. However there are more recent reports of long-term adverse effects, mainly persistent neuropsychiatric disturbances and sexual dysfunction.¹⁴

Intralesional corticosteroids

Severe inflammatory cysts may sometimes be treated with intralesional injection of triamcinolone acetonide. This would be done by a member of a consultant dermatologist-led team but remains 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. Co-cyprindiol should not be used for longer than 6 months.

• Consider referring people with acne and polycystic ovary syndrome with additional features of hyperandrogenism to an 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 scarring¹⁵

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.

Complications of acne vulgaris^{16 1}

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.

Prognosis¹²

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.