Acne - clinical fact sheet and MCQ

Overview

Acne is a chronic inflammatory condition of the pilosebaceous unit in the skin. The condition arises exclusively in the presence of androgens and is typically due to increased sensitivity of the pilosebaceous unit to circulating androgens, rather than elevated androgen levels. 

Adolescents and young adults are more commonly affected. In males, acne tends to be more severe, with peak onset in early puberty and resolving by the third decade of life. Conversely, females often experience acne persisting into older age, even as late as their forties. Acne can also manifest in infants.

Due to the involvement of the pilosebaceous unit, the most commonly affected areas are those of high sebaceous gland density, such as the face, neck, chest, shoulders, and upper back. Beyond being a dermatological condition, acne can have significant emotional and social repercussions, potentially leading to depression or anxiety, which need to be considered when managing these patients.

Diagnosis

Contributors for an increased risk of acne include:

• systemic medications such as anticonvulsants and steroids

• excessive sunlight exposure, which can exacerbate inflammation and pro-fibrotic responses

• comedogenic topical products such as oil-based skincare products or cosmetics

• genetic factors (family history of acne in up to 90%)

• high glycaemic load diets and dairy products

• psychological stress

Red flags that may indicate an underlying hyperandrogenisation disorder in females include obesity, menstrual disorders, and hirsutism, in which case consider further investigations for endocrine conditions, such as polycystic ovary syndrome.

Diagnosis of acne is predominantly by clinical examination. Comedones (open or closed) must be present along with pustules or papules. Conditions that mimic acne include bacterial or fungal folliculitis, keratosis pilaris, and milia.

Acne severity can be defined as:

• mild: a few comedones, pustules, and papules, typically limited to the "T-zone" (forehead, nose, and chin), with no scarring

• moderate: numerous comedones, pustules, and papules, with occasional nodules but no scarring; lesions often extend to the trunk

• severe: nodules, cysts, and scarring affecting the face and trunk

Severity classification may also be influenced by the impact on quality of life.

Management

Management involves addressing contributing factors, minimising aggravating elements, and tailoring treatment to the severity and type of acne.

1. General measures:

• assess and modify factors such as contributing systemic drugs (eg, anabolic steroids, progestogen-only contraceptives, combined oral contraceptive pill with high-dose levonorgestrel) and potentially comedogenic (oil-based) skincare products

• evaluate dietary influences such as high glycaemic index foods and dairy products

• address occupational or environmental factors like exposure to comedogenic substances (eg, cooking grease in the kitchen) or humid environments (eg, spas and saunas)

• consider early referral to a dermatologist if:

1. acne is severe

2. scarring is evident

3. there is family history of severe scarring from acne

4. acne is refractory to treatment or repeatedly recurs

5. patient is demonstrating significant psychological distress

2. Mild acne:

• initial treatment involves over-the-counter (OTC) topical treatments such as benzoyl peroxide, salicylic acid, azelaic acid, or niacinamide

• combine products for an additive effect, but monitor for irritation

• when OTC products are inadequate:

1. if predominantly comedonal with minimal inflammation: change to a topical retinoid

2. if predominantly comedonal with some inflammation: change to a combination of topical benzoyl peroxide and topical retinoid

3. if predominantly inflammatory with some comedones: change to topical benzoyl peroxide with topical antibiotic for anti-inflammatory effect (cease antibiotic once inflammation has resolved)

4. if equally comedonal and inflammatory: change to combination topical retinoid and topical antibiotic (cease antibiotic once inflammation has resolved)

• if topical treatments are insufficient or not well-tolerated, add or switch to oral therapy as for moderate to severe acne outlined below

• note that acne severity does not always correlate with emotional distress; rapid escalation of treatment may be necessary if quality of life is significantly impacted.

3. Moderate to severe acne:

• inflammatory papules and pustules with some comedones: combine oral tetracycline antibiotics with topical benzoyl peroxide and a retinoid (cease antibiotic once inflammation has resolved)

• additional considerations for patients on antibiotics:

1. avoid long term use of oral antibiotics; replace with topical formulation for maintenance once inflammation is controlled

2. counsel patients on tetracyclines regarding sun protection, management of gastrointestinal upset, and symptoms of intracranial hypertension

• predominantly comedonal acne with minimal inflammation: consider early referral to a dermatologist for oral isotretinoin

4. Acne related to hyperandrogenism in females:

• combined oral contraceptive pill (COCP) may replace oral antibiotics or may replace topical treatment as an adjunct to oral antibiotics for moderate to severe acne

• consider spironolactone as an antiandrogen if COCP contraindicated or insufficient as monotherapy 

5. Acne in pregnant patients or those trying to conceive:

• retinoids are teratogenic and should be avoided in pregnant patients or those trying to conceive, but topical applications are considered low-risk in lactation (ensure baby does not come into contact with treated skin)

• spironolactone is contraindicated in pregnancy

• oral erythromycin may be considered as an alternative to tetracyclines in pregnant patients with moderate to severe acne

• cosmetic skin therapies such as laser therapy, microneedling, and chemical peels may be considered for temporary improvement but should be performed by properly trained clinicians

References

Therapeutic Guidelines. Acne. 2022. (last viewed January 2025).

Therapeutic Guidelines. Rosacea. 2022. (last viewed January 2025).

Therapeutic Guidelines. Seborrhoeic dermatitis. 2022. (last viewed January 2025).

Therapeutic Guidelines. Cutaneous lupus erythematosus. 2022. (last viewed January 2025).

Sutaria AH, Masood S, Saleh HM, et al. Acne Vulgaris. [Updated 2023 Aug 17]. In: StatPearls [Internet]. Treasure Island (FL): StatPearls Publishing; 2025. 

Piquero-Casals J, Morgado-Carrasco D, Rozas-Muñoz E, et al. Sun exposure, a relevant exposome factor in acne patients and how photoprotection can improve outcomes. J Cosmet Dermatol. 2023;22(6):1919-1928. doi: 10.1111/jocd.15726.

Drugs and Lactation Database (LactMed®) [Internet]. Bethesda (MD): National Institute of Child Health and Human Development; 2006. Tretinoin. [Updated 2024 Oct 15]. (last viewed January 2025).

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