Class Explorer · Anti-infectives
Tetracyclines
Bind the 30S ribosomal subunit and block tRNA docking. Broad, intracellular, and reliably active against the organisms nothing else reaches.
Members
Also in this class: Minocycline · Tigecycline. Full pages arrive as the library grows.
Compare the members
Doxycycline
- Renal adjustment
- None needed
- Note
- Take upright, with water, away from cations
Shared across the class
- Indications
- Atypical pneumonia · Tick-borne illness · Acne and rosacea · Chlamydia · Skin and soft tissue infection including community MRSA
- Adverse effects
- Photosensitivity · Oesophagitis if taken lying down · Gastrointestinal upset · Tooth discolouration in young children
- Contraindications
- Pregnancy · Children under 8 years, with exceptions for serious rickettsial illness
- Monitoring
- Clinical response · Sun exposure advice, which is a real and common failure point in summer
What makes each agent different
- Doxycycline is largely non-renally cleared, so it needs no adjustment in kidney disease, which distinguishes it from most broad oral antibiotics.
- Minocycline penetrates the CNS better and causes more vestibular effects and, rarely, pigmentation.
Divalent cations (calcium, magnesium, iron, antacids) chelate it into uselessness. The same trap as the fluoroquinolones, and just as often missed.
Take with a full glass of water and stay upright for 30 minutes: pill oesophagitis from doxycycline is genuinely painful and entirely preventable.
Last reviewed 2026-08-16 · Goodman & Gilman's The Pharmacological Basis of Therapeutics, 14th ed.