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Acne Vulgaris

BASICS

Description

  • Disorder of the pilosebaceous units, chronic inflammatory dermatosis.
  • Characterized by open/closed comedones, papules, pustules, and/or nodules.

Geriatric Considerations

  • Favre-Racouchot syndrome: comedones due to sun exposure on face/head.

Pregnancy Considerations

  • Acne may flare or remit.
  • Typically improves in first trimester, may worsen in third.
  • Safe treatments: topical benzoyl peroxide (BP), azelaic acid, erythromycin, clindamycin; oral erythromycin, azithromycin, cephalexin, amoxicillin.
  • Avoid: topical tretinoin, trifarotene, adapalene (retinoid embryopathy risk); isotretinoin (Category X), tazarotene, tetracycline, doxycycline, minocycline, sarecycline.

Pediatric Considerations

  • Neonatal acne (0-8 weeks): lesions on face; self-limited; treat with topical ketoconazole 2%.
  • Infantile acne (6 weeks–1 year): lesions on face, neck, back, chest; topical/systemic therapy.
  • Early/mid childhood acne (1–7 years): rare; evaluate for hyperandrogenism.
  • Preadolescent acne (7–12 years): common; 47% prevalence; usually due to adrenal awakening; comedonal lesions.
  • Avoid tetracyclines in children <8 years; otherwise, treatment similar to adolescents.

EPIDEMIOLOGY

  • Predominant age: early to late puberty; 20-40% persist into 4th decade.
  • Sex distribution: male > female in teens; female > male in adults.
  • Prevalence:
  • 80-95% adolescents affected.
  • Adults 25–34 years: 8%.
  • Adults 35–44 years: 3%.
  • African Americans 37%, Hispanics 32%, Caucasians 24%.

ETIOLOGY AND PATHOPHYSIOLOGY

  • Androgens (testosterone, DHEA-S) stimulate sebum production and keratinocyte proliferation.
  • Follicular occlusion by keratin plug → sebum accumulation → follicular distension.
  • Cutibacterium acnes phylotype IA1 colonizes follicles, producing proinflammatory cytokines (IL-1).
  • Familial association in 50%.

RISK FACTORS

  • Increased endogenous androgen effect.
  • Oily cosmetics, cocoa butter, PVC, chlorinated hydrocarbons, cutting oil.
  • Occlusion (helmets, shoulder pads, phones, masks - "maskne").
  • Drugs: androgenic steroids, lithium, phenytoin.
  • Endocrine disorders: PCOS, Cushing’s, congenital adrenal hyperplasia, androgen-secreting tumors, acromegaly.
  • Psychological stress.
  • High glycemic load, dairy, whey protein.
  • Smoking worsens severe acne.

GENERAL PREVENTION

  • Avoid risk factors.

COMMONLY ASSOCIATED CONDITIONS

  • Acne conglobata, hidradenitis suppurativa.
  • Pomade acne (hair oils).
  • SAPHO syndrome.
  • PAPA syndrome and SAHA.
  • Dark skin: 50% keloidal scarring and post-acne hyperpigmentation.

DIAGNOSIS

History

  • Duration, relation to menses, medications, cleansers, stress, smoking, diet, family history.

Physical Exam

  • Closed comedones (whiteheads), open comedones (blackheads).
  • Nodules, papules, pustules, cysts.
  • Scars: ice pick, rolling, boxcar, atrophic macules, hypertrophic, sinus tracts.
  • No universal grading; AAD grading:
  • Mild: few papules/pustules, no nodules.
  • Moderate: some papules/pustules, few nodules.
  • Severe: many papules/pustules/nodules.
  • Very severe: acne conglobata, fulminans, inversa.
  • Areas affected: face, chest, back, upper arms.
  • Adult females: facial lesions not limited to mandibular/perioral area.

Differential Diagnosis

  • Folliculitis (gram-negative/positive, pityrosporum).
  • Rosacea, steroid-induced acne, perioral dermatitis.
  • Pseudofolliculitis barbae.
  • Drug eruptions.
  • Keratosis pilaris.
  • Sarcoidosis.
  • Seborrheic dermatitis.
  • Lupus erythematosus.

DIAGNOSTIC TESTS & INTERPRETATION

  • Labs only if androgen excess suspected: free/total testosterone, DHEA-S, LH, FSH.

TREATMENT

Comedonal (Grade 1)

  • Keratinolytic agents.

Mild inflammatory (Grade 2)

  • Benzoyl peroxide ± topical retinoid or ± topical antibiotic.

Moderate inflammatory (Grade 3)

  • Add systemic antibiotic (time-limited) to Grade 2 regimen.

Severe inflammatory (Grade 4)

  • As in Grade 3 or isotretinoin.

Medication Details

  • Topical retinoids + antimicrobial agents are first-line beyond mild disease.
  • Avoid antibiotics as monotherapy; combine with benzoyl peroxide.
  • Vehicles: creams/lotions for dry skin; gels/solutions for oily skin.
  • Apply topical agents to entire affected area.
  • Mild soap daily; avoid abrasive/drying agents; use gentle cleanser and moisturizer.

Keratinolytic Agents

  • α-Hydroxy acids, salicylic acid, topical retinoids, azelaic acid.
  • Side effects: dryness, erythema, scaling; start low/alternate days.

Retinoids

  • Tretinoin: 1st gen, various strengths; apply to dry skin at bedtime; initial flare possible; avoid in pregnancy.
  • Adapalene (Differin): 0.1%, less irritating, OTC available.
  • Tazarotene: 3rd gen, most effective and irritating; teratogenic.
  • Trifarotene (Aklief): 4th gen, selective, safer.

Azelaic Acid

  • 20% cream BID; antibacterial, anti-inflammatory; reduces postinflammatory hyperpigmentation; safe in pregnancy.

Salicylic Acid

  • 0.5–2%; less effective/irritating than tretinoin.

Benzoyl Peroxide (BP)

  • Generates oxygen free radicals; no bacterial resistance.
  • 2.5% as effective as higher concentrations.
  • Apply BP in morning, tretinoin at night.
  • Side effects: irritation, bleaching, photosensitivity.

Topical Antibiotics

  • Erythromycin, clindamycin, minocycline foam, metronidazole.
  • Use in combination with BP; avoid monotherapy.

Other Topicals

  • Sodium sulfacetamide for seborrheic dermatitis or rosacea.
  • Dapsone gel for adult females; rare methemoglobinemia risk.

Oral Antibiotics

  • Limit to 6-12 weeks (max 6 months).
  • Used in severe, trunk involvement, or scarring risk.
  • Tetracycline, doxycycline, minocycline, erythromycin, TMP-SMX, azithromycin, amoxicillin.

Oral Retinoids

  • Isotretinoin: 0.5–1 mg/kg/day BID; max 2 mg/kg/day.
  • Cure rate 60-90%; 20% relapse.
  • Side effects: teratogenicity, dryness, hypertriglyceridemia, hepatitis, psychosis, others.
  • Avoid tetracyclines or vitamin A during treatment.
  • Monthly labs & pregnancy testing; iPLEDGE registration required.

Female-only Medications

  • FDA-approved OCPs (drospirenone/ethinyl estradiol best).
  • Spironolactone 25–200 mg/day (antiandrogen, not FDA-approved for acne).
  • Clascoterone 1% topical cream (antiandrogen).

ISSUES FOR REFERRAL

  • Acne scar management.

ADDITIONAL THERAPIES

  • Hyperpigmentation: hydroquinone, azelaic acid, corticosteroids, dapsone gel, sunscreen.
  • Light-based therapies: UVA/UVB, blue/red light, pulse dye, infrared laser, photodynamic therapy.

SURGERY/PROCEDURES

  • Comedo extraction.
  • Intralesional triamcinolone injection for cysts.
  • Acne scar treatments: retinoids, steroids, cryosurgery, microdermabrasion, chemical peels, laser resurfacing, microneedling, fillers, punch elevation.

COMPLEMENTARY & ALTERNATIVE MEDICINE

  • Tea tree oil, some plant extracts, green tea extract may be useful.

ONGOING CARE

Follow-Up

  • Limit oral antibiotics to 3 months; taper topicals as lesions resolve.

Diet

  • High-glycemic foods, milk chocolate, skim milk may worsen acne.
  • Paleo diet and omega-3 fatty acids may help.

Patient Education

  • Initial worsening possible.
  • Improvement typically in 4+ weeks.

PROGNOSIS

  • Gradual improvement over 8-12 weeks after treatment start.

COMPLICATIONS

  • Acne conglobata with scarring and psychological distress.
  • Postinflammatory hyperpigmentation and keloids more common in darker skin.

REFERENCES

  1. Kolli SS, Pecone D, Pona A, et al. Topical retinoids in acne vulgaris: a systematic review. Am J Clin Dermatol. 2019;20(3):345-365.
  2. Marson JW, Baldwin HE. Overview of acne therapy, part 1: topical, oral antibiotics, light therapy, diet. Dermatol Clin. 2019;37(2):183-193.

See Also

  • Acne Rosacea

Algorithms

  • Acne

Codes

Code Description
L70.0 Acne vulgaris

Clinical Pearls

  • Decrease topical application frequency to reduce irritation.