Acne vulgaris is a chronic skin condition that most commonly affects adolescents and young adults, but it can occur at any age. The etiology of acne is multifactorial: genetic predisposition, hormonal effects on sebum production, bacterial colonization with Cutibacterium acnes, and/or keratin plugs from follicular hyperkeratosis. Acne manifests as noninflammatory comedonal acne and/or inflammatory acne, e.g., papules and/or nodules that are often located on the face, shoulders, upper chest, and back. History and physical examination are usually sufficient for diagnosis. Diagnostic studies are only indicated for differential diagnosis or if an underlying medical condition is suspected, e.g., polycystic ovary syndrome (PCOS). Prompt pharmacological treatment is recommended to prevent complications of acne. Treatment is based on the severity of acne and the type of lesion; options include topical and systemic medications.
- Prevalence: the most prevalent chronic skin condition in the US, affecting ∼ 50 million people 
- Age of onset: typically by 11–12 years, with symptoms usually disappearing around 20–30 years of age 
- Sex: more common in male individuals during adolescence; , but more common in women during adulthood
Epidemiological data refers to the US, unless otherwise specified.
Causes of acne vulgaris
- Genetic predisposition 
- Hormonal factors
- Follicular hyperkeratosis: Higher keratinocyte activity and decreased keratinocyte shedding in pilosebaceous units leads to the formation of comedones.
- Bacterial colonization with Cutibacterium acnes; (formerly known as Propionibacterium acnes) → inflammatory reactions with formation of papules, nodules, pustules, and/or cysts
Risk factors for acne vulgaris
- Commonly found in areas with sebaceous glands (predilection sites: face, shoulders, upper chest, and back)
- Noninflammatory acne: comedonal acne
- Inflammatory acne: Affected areas are red and can be painful.
- Severity 
- Mild acne
- Moderate acne
- Severe acne: extensive skin involvement
Patients with inflammatory acne are at risk for scarring. 
Subtypes and variants
Acne fulminans 
- Rare disease (approx. 200 documented cases)
- Age of onset: 13–22 years
- ♂ > ♀ (3:1)
- Mainly individuals of northern European descent
- Adverse effect of (most common)
- Primary lesions
- Systemic manifestations
- Refer urgently to dermatology.
- Discontinue isotretinoin if lesions develop while taking this medication.
- Initiate monotherapy with systemic corticosteroids for at least 2–4 weeks.
- Once lesions have improved, continue systemic corticosteroids while initiating low-dose isotretinoin.
- Patients with treatment resistance : Consider cyclosporine, biologics (e.g., infliximab, anakinra), or dapsone.
- Acne vulgaris is usually a clinical diagnosis.
- Consider diagnostic studies if an underlying pathology or alternative diagnosis is suspected, e.g.: 
Routine testing for C. acnes is not recommended because it does not alter management. 
- Perform a thorough clinical evaluation and address any underlying risk factors for acne vulgaris.
- Provide supportive care instructions.
- Start .
- Manage patient expectations.
- It may take 4–6 weeks for the affected skin to start improving and ≥ 2 months for resolution. 
- Trial and error is often required to find the best regimen.
- Reassess therapy response and provide as indicated.
- Consider referral to a dermatologist for:
Early pharmacological treatment is recommended to prevent . 
Supportive care 
- Provide general skin care instructions. 
- Use a gentle facial cleanser and avoid excessive cleaning and scrubbing (e.g., with exfoliants). 
- Avoid skin care products (e.g., moisturizers, cosmetics) that are comedogenic.
- Do not pick at acne lesions.
- For individuals with endocrine-related acne (e.g., due to PCOS, obesity), recommend maintaining a healthy BMI.
- Dietary restrictions and supplements (e.g., fish oil) are not supported by current evidence. 
Overview of pharmacological therapy 
The preferred initial treatment regimen is based on the lesion type and severity of acne.
|Overview of initial acne treatment by severity |
Procedural interventions 
Although there is insufficient evidence on the efficacy of procedural interventions, they may be considered by a dermatologist.
- Topical treatments are used to treat all stages of acne.
- A mixture of topical therapies is often required; use of fixed combination products may improve adherence.
- When prescribing, consider the following to optimize therapy : 
- Medication concentration
- Type of topical formulation (e.g., gel, lotion)
- Duration of skin contact
Topical retinoids 
- Retinoids are vitamin A derivatives with an anti-inflammatory and comedolytic effect.
- Used as monotherapy for comedonal acne or adjunctive therapy for acne of any severity
- Applied at night as some preparations are not photostable and all retinoids can cause photosensitivity
Commonly used agents 
- Tazarotene 
- Adapalene alone or in combination with benzoyl peroxide 
- Tretinoin alone or in combination with clindamycin 
Topical antibiotics for acne 
- Help manage acne through both a bactericidal and anti-inflammatory effect
- Used as an adjunctive therapy for acne
Commonly used agents
- Preferred: clindamycin alone or in combination with benzoyl peroxide 
- Alternative: erythromycin alone or in combination with benzoyl peroxide 
Avoid using topical antibiotics as monotherapy and limit the length of therapy to 12 weeks to prevent the development of drug-resistant bacteria.
Other topical agents 
- Consider as monotherapy treatment for mild acne or adjunctive treatment for moderate acne
- Options include: 
General principles 
- Indicated for moderate to severe inflammatory acne
- Always combine with topical treatments (i.e., benzoyl peroxide or a retinoid) to:
- Limit treatment to < 4 months to prevent antibiotic resistance. 
Recommended antibiotics 
- First line: tetracyclines
- Alternative: macrolides
Alternative oral antibiotics (e.g., cephalosporins, penicillins, or trimethoprim/sulfamethoxazole) are not recommended for treating acne because of limited evidence, but can be considered if preferred regimens are not tolerated or acceptable (e.g., during pregnancy). 
- Medications with an antiandrogenic effect (e.g., COCPs and aldosterone antagonists) can help female individuals with inflammatory acne.
- Choice of antiandrogenic treatment is based on:
- Patient preference
- Presence of
- Glucocorticoids can be used for select indications in patients of both sexes.
Combined oral contraceptive pill (COCP) 
- Can be used alone or in combination with other acne therapies
- Prior to initiation, exclude contraindications and discuss .
- Acne in patients seeking contraception
- Consider in female individuals of reproductive age with acne and: 
- Symptoms that worsen with menstruation
- Limited response to other acne therapies
- Triphasic norgestimate/ethinyl estradiol
- Triphasic norethindrone acetate/ethinyl estradiol/ferrous fumarate
- Drospirenone/ethinyl estradiol
- Drospirenone/ethinyl estradiol/levomefolate
Users of progestin-only contraception often report worsening of acne. It is unclear what impact the new progestin-only pill containing drospirenone, an antiandrogenic progestin, has on hormonal acne. 
- Spironolactone (off label) can be used for hormonal acne. 
- Can be used in combination with COCP or as an alternative for patients with .
- Evidence on efficacy is limited but side effects are usually mild at lower doses.
Contraception is generally recommended for women of reproductive age who are taking spironolactone, which can have antiandrogenic effects on a developing fetus (e.g., feminization of a male fetus). 
- Indicated for use as an adjunctive therapy in certain scenarios:
- Consider referral to a dermatologist for management.
Acne can worsen with rapid titration of glucocorticosteroids; avoid long-term treatment to minimize the . 
General principles 
- Isotretinoin is a systemic vitamin A derivative.
- Decreases the concentration of C. acnes and inflammation by decreasing sebum production and promoting comedolysis 
- Severe; , nodular, recalcitrant acne
- Moderate acne requiring therapy escalation
- Absolute contraindications include:
- Relative contraindications include:
Initiating isotretinoin therapy 
- Discuss risks and benefits of therapy with patients.
- Explain the mandatory iPLEDGE risk management program and enroll the patient.
One month prior to treatment for patients who can become pregnant:
- Perform the first of two serum and/or urine pregnancy tests to confirm the patient is not pregnant.
- Provide birth defects. and risk for
- Initiate two methods of contraception. 
- Repeat the pregnancy test after at least 30 days of using two approved forms of contraception, prior to starting isotretinoin. 
- Obtain baseline liver chemistries, cholesterol, and triglycerides.
- Stop any medications that may interact with isotretinoin, e.g., oral tetracyclines. 
- Based on the severity of acne, select the appropriate starting dose of isotretinoin. 
- Consider prescribing an oral glucocorticosteroid (e.g., prednisone ) when starting isotretinoin.
- Advise patients not to donate blood : 
- During treatment
- For at least one month after treatment
Ongoing management of isotretinoin therapy 
- Schedule monthly follow-up to:
- For patients with severe acne, uptitrate isotretinoin after one month.
- Monitor liver chemistries, cholesterol, and triglycerides at least once during treatment. 
- Treatment duration is usually 15–20 weeks to attain a cumulative dose of 120–150 mg/kg. 
- After treatment is complete:
Patients planning to conceive should discontinue treatment at least one month prior to conception.
Adverse effects of isotretinoin 
- Dermatological: dry skin, cheilitis, alopecia, acne fulminans
- Hematologic: cytopenias, venous thromboembolism
- Neurological: medication-induced intracranial hypertension, psychiatric disorders, hearing impairment
- Ophthalmic: corneal opacities, decreased night vision
- Musculoskeletal: arthralgia, osteoporosis, delayed bone healing, premature epiphyseal closure
- Nonspecific symptoms: headaches, fatigue
- Drug interactions (e.g., with tetracyclines or contraceptives)
- Possible delayed wound healing after elective procedures (e.g., dermabrasion for acne scarring) 
Fetal retinoid syndrome 
- Congenital CNS defects
- Cardiac conditions: congenital heart disease (e.g., great vessel anomalies)
- Congenital craniofacial anomalies (i.e., dysmorphic features)
- Perform a clinical evaluation after 4–8 weeks to assess the patient's response to treatment. 
- If treatment response is poor :
- Assess treatment adherence and consider adjusting the current treatment regimen. 
- If further adjustments do not help, consider referring to a dermatologist for management.
- If there is improvement, consider transitioning to maintenance therapy for acne, e.g. : 
Following the initiation of an acne medication regimen, it typically takes 4–6 weeks to notice clinical improvement and at least 2–3 months to see clearing. 
Special patient groups
Acne in infants
Neonatal cephalic pustulosis 
- Epidemiology: affects up to 20% of infants 
- Pathophysiology: unclear; thought to result from an overgrowth of the fungal species Malassezia
- Clinical presentation: : onset in the first few weeks of life of a papulopustular rash without comedones
Infantile acne 
- More common in boys
- Affects < 2% of children. 
- Clinical presentation
Acne in pregnancy 
- Pregnancy-related changes in maternal androgens can alleviate or worsen acne.
- Inflammatory acne is more common than noninflammatory acne; the trunk is often affected.
- Follow standard treatment of acne by severity using agents that are safe in pregnancy.
Agents safe to use during pregnancy 
- Topical agents
- Certain systemic antibiotics
Agents to be used with caution during pregnancy 
Only use the following medications if the potential benefit outweighs the potential or unknown risks to the fetus.
- Topical agents
- Systemic agents
- Intralesional corticosteroids 
Agents to avoid during pregnancy 
The following agents are contraindicated in women who are pregnant or planning pregnancy.