What is the recommended dose of doxycycline (antibiotic) for a typical patient with moderate to severe acne?

Doxycycline Dosing for Acne

For moderate to severe inflammatory acne, the standard dose is 200 mg on day 1 (administered as 100 mg every 12 hours), followed by 100 mg daily as maintenance, and this must always be combined with topical benzoyl peroxide and/or a retinoid to prevent bacterial resistance. 1, 2

Standard Dosing Regimen

Adults and Children Over 100 Pounds

• Loading dose: 200 mg on day 1, given as 100 mg every 12 hours 1, 2
• Maintenance dose: 100 mg daily thereafter 1, 2
• The FDA label confirms this as the standard dosing for oral doxycycline 2

Children 8 Years and Older Weighing Less Than 100 Pounds

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

Critical Treatment Principles

Monotherapy with doxycycline is explicitly contraindicated—you must prescribe concurrent topical benzoyl peroxide and/or a retinoid. 1, 3 This is non-negotiable according to the American Academy of Dermatology, as monotherapy promotes antibiotic resistance and violates antibiotic stewardship principles. 1

Mandatory Combination Therapy

• Continue topical benzoyl peroxide and/or retinoid throughout the entire course of doxycycline 1, 3
• Maintain topical therapy even after discontinuing the antibiotic for long-term maintenance 1, 3
• The topical retinoid provides comedolytic and anti-inflammatory effects that complement doxycycline 1

Treatment Duration

• Limit doxycycline to 3-4 months maximum 1, 3
• Re-evaluate at 3-4 months to assess response and minimize bacterial resistance development 1, 3
• Discontinuing all therapy after stopping doxycycline leads to high recurrence rates—acne requires long-term maintenance with topicals 3

Alternative Dosing: Subantimicrobial Approach

For patients concerned about antibiotic resistance or side effects, subantimicrobial dosing (20 mg twice daily or 40 mg daily modified-release) has demonstrated efficacy in moderate inflammatory acne with significantly fewer gastrointestinal side effects than standard dosing. 1, 4, 5, 6

• Modified-release doxycycline 40 mg once daily showed comparable efficacy to 100 mg daily but with markedly lower drug-related adverse events (similar to placebo) 4
• This subantimicrobial approach still requires combination with topical benzoyl peroxide 1

Absolute Contraindications

• Children under 8 years of age (risk of permanent tooth discoloration and bone growth inhibition) 1, 3, 2
• Pregnancy (Category D) 1, 3
• Nursing mothers 1
• Hypersensitivity to tetracyclines 1

Important Drug Interactions

Doxycycline interacts with multiple medications that can reduce its absorption or increase toxicity: 1, 3

• Antacids and iron-containing preparations (reduce absorption)
• Bismuth subsalicylate and proton-pump inhibitors
• Hormonal contraceptives (may reduce contraceptive efficacy)
• Oral anticoagulants (may potentiate anticoagulation)
• Isotretinoin (avoid concurrent use)

Common Side Effects and Management

• Gastrointestinal disturbances are more frequent with doxycycline than minocycline, particularly at higher doses 3, 7
• Photosensitivity is common—counsel patients on strict sun protection 1, 3
• Administer with adequate fluids to reduce risk of esophageal irritation and ulceration 2
• May be taken with food or milk if gastric irritation occurs, as absorption is not significantly affected 2

When to Escalate Therapy

If inadequate response after 3-4 months of doxycycline with appropriate topical therapy, strongly consider referral for isotretinoin evaluation, particularly for severe cystic acne. 8 For women with hormonal components, combined oral contraceptives or spironolactone may be considered as adjunctive or alternative therapy. 3