Adults: 100 mg orally every 12 hours on the first day, then 100 mg once daily or 100 mg every 12 hours depending on infection
Children ≥8 years: 2–4 mg/kg/day in divided doses
Note: Avoid use in children under 8 years and during pregnancy due to risk of teeth discoloration and bone effects.
Route of Administration
Oral (capsule, tablet, suspension), IV
Mechanism of Action
Doxycycline inhibits bacterial protein synthesis by binding to the 30S ribosomal subunit, preventing aminoacyl-tRNA from attaching to the ribosome and halting bacterial growth.
Common Adverse Effects
Nausea, vomiting
Diarrhea
Photosensitivity
Esophageal irritation
Serious Adverse Effects
Severe hypersensitivity reactions (rare)
Hepatotoxicity
Intracranial hypertension (rare)
Clostridioides difficile–associated diarrhea
Contraindications
Hypersensitivity to doxycycline or other tetracyclines
Pregnancy (especially 2nd and 3rd trimester)
Children under 8 years
Precautions
Avoid prolonged sun exposure due to photosensitivity
Use with caution in liver impairment
Take with a full glass of water and remain upright to prevent esophageal irritation