What is the recommended dose of doxycycline (antibiotic) for an adult patient with periodontitis?

Doxycycline Dosing for Periodontitis

For chronic periodontitis, the recommended dose is doxycycline 20 mg orally twice daily for 3 months as an adjunct to scaling and root planing (SRP). 1

Dosing Regimen

• Sub-antimicrobial dose doxycycline (SDD): 20 mg orally twice daily 1
• Duration: 3 months minimum, up to 9-24 months for sustained benefit 2, 3
• Must be combined with thorough scaling and root planing 1, 3

Mechanism and Rationale

• This sub-antimicrobial dose works through host modulation, not antimicrobial activity 2, 3
• Inhibits matrix metalloproteinases (MMPs) that destroy periodontal tissues 2, 3, 4
• Does not cause antimicrobial resistance or alter oral microbiome at this dose 3, 5

Clinical Efficacy

The evidence from multiple randomized controlled trials demonstrates:

• Probing depth reduction of 0.9 mm beyond SRP alone 1
• Clinical attachment level gain of 0.88 mm beyond SRP alone 1
• Significant reductions in bleeding on probing and gingival inflammation 6, 5

Important Distinctions

Do not confuse this with antimicrobial-dose doxycycline (100 mg twice daily), which is NOT indicated for periodontitis. 7, 8 The standard antimicrobial dose of 100 mg twice daily is used for acute dental infections requiring bacterial killing, not chronic periodontitis management. 7, 8

Treatment Algorithm

1. Perform thorough scaling and root planing first 1, 3
2. Initiate SDD 20 mg twice daily immediately after SRP 1
3. Continue for minimum 3 months 2, 3, 6
4. Re-evaluate clinical parameters at 3-month intervals 3, 5
5. Consider extending therapy up to 9-24 months for severe cases or sustained benefit 2, 5

Administration Considerations

• Take with a full glass of water and remain upright for 1 hour to prevent esophagitis 1
• Can be taken with food or milk if gastric irritation occurs 8
• Separate dosing by 2 hours from dairy products, antacids, calcium, iron, or magnesium supplements 1
• Use sun protection due to photosensitivity risk 1

Common Pitfalls to Avoid

• Do not prescribe 100 mg twice daily for chronic periodontitis - this antimicrobial dose is for infections, not host modulation 7, 8
• Do not use SDD without concurrent mechanical debridement (SRP) - the benefit requires thorough bacterial burden reduction first 3
• Do not discontinue therapy before 3 months - shorter courses have not demonstrated sustained clinical benefit 2, 3
• Do not use for acute dental abscesses or apical periodontitis - these require surgical intervention, not host modulation 1, 7