What is the recommended dose of doxycycline (antibiotic) for treating moderate to severe acne?

Doxycycline Dosing for Acne

For moderate to severe inflammatory acne, the American Academy of Dermatology recommends a loading dose of 200 mg on day 1 (administered as 100 mg every 12 hours), followed by a maintenance dose of 100 mg daily for adults and children over 100 pounds, and this must always be combined with topical benzoyl peroxide and/or a retinoid to prevent bacterial resistance. 1

Standard Dosing Regimen

Adults and Children >100 pounds

• Loading dose: 200 mg on day 1, given as 100 mg every 12 hours 1
• Maintenance dose: 100 mg daily thereafter 1
• Treatment duration: Limited to 3-4 months maximum with mandatory re-evaluation to minimize bacterial resistance development 1, 2

Children ≥8 years and <100 pounds

• Loading dose: 2 mg/lb body weight divided into 2 doses on day 1 1, 3
• Maintenance dose: 1 mg/lb body weight daily (can be given as single daily dose or divided into 2 doses) 1, 3

Alternative Subantimicrobial Dosing

Even subantimicrobial doses of doxycycline (20 mg twice daily or 40 mg daily modified-release) have demonstrated efficacy in moderate inflammatory acne with superior safety profiles and reduced gastrointestinal side effects compared to standard 100 mg dosing. 1, 2, 4

• This lower-dose option may be considered for patients who cannot tolerate standard dosing 5, 4
• The modified-release 40 mg formulation showed comparable efficacy to 100 mg with markedly fewer drug-related adverse events 4

Mandatory Combination Therapy

Monotherapy with doxycycline is explicitly contraindicated—you must always combine it with topical benzoyl peroxide and/or a retinoid throughout treatment and continue these topical agents for maintenance after antibiotic discontinuation. 1, 2

This combination approach:

• Prevents bacterial resistance development 1, 2
• Provides synergistic therapeutic effects 6
• Addresses multiple pathogenic mechanisms of acne 1

Absolute Contraindications

• Children <8 years of age: Risk of permanent tooth discoloration and enamel hypoplasia 1, 3
• Pregnant women: Pregnancy Category D 1, 2
• Nursing mothers 1
• Hypersensitivity to tetracyclines 1

For children <8 years requiring systemic treatment, erythromycin should be used instead 3

Critical Drug Interactions and Administration Pearls

• Avoid concurrent administration with: Antacids, calcium supplements, iron preparations, dairy products, bismuth subsalicylate, and proton-pump inhibitors (these decrease absorption) 1, 3
• Take with adequate water to prevent esophageal irritation 3
• Counsel on photosensitivity: More common with doxycycline than minocycline; strict sun protection required 1, 2
• Monitor hormonal contraceptive efficacy: Doxycycline may interact with oral contraceptives 1, 2

Common Pitfalls to Avoid

• Never use doxycycline as monotherapy—this violates antibiotic stewardship principles and promotes resistance 1, 2
• Do not combine topical dapsone with benzoyl peroxide if using dapsone, as this causes orange-brown skin discoloration 1
• Do not extend treatment beyond 3-4 months without re-evaluation due to resistance concerns 1, 2
• Gastrointestinal disturbances occur more frequently with doxycycline than minocycline, particularly at higher doses 2, 6

When to Consider Alternatives

• For treatment failures: Consider isotretinoin referral for severe acne unresponsive to oral antibiotics 2, 3
• For hormonal acne patterns in females: Combined oral contraceptives or spironolactone may be considered as adjunctive or alternative therapy 2, 3
• For mild acne: Doxycycline is not indicated; use topical therapies only 1