Doxycycline Pediatric Dosing Calculator
Calculate doxycycline dosage for children by weight and indication. Covers tick-borne illness (RMSF, Lyme), community-acquired pneumonia, acne, malaria prophylaxis, and anthrax PEP. Includes suspension volume and tablet dosing with AAP 2020 safety guidance.
Inputs
Disclaimer: For educational purposes only. Not a substitute for clinical judgment. Always verify doses with current guidelines and pharmacy references.
About This Tool
What Is Doxycycline?
Doxycycline is a broad-spectrum tetracycline antibiotic widely used in pediatrics for tick-borne illnesses, atypical pneumonia, acne, and malaria prophylaxis. It is available as an oral suspension (25 mg/5 mL), tablets (50 mg, 75 mg), and capsules (100 mg). Doxycycline is bacteriostatic, inhibiting bacterial protein synthesis by binding the 30S ribosomal subunit. It has excellent oral bioavailability and tissue penetration.
Doxycycline Dosing in Children
Pediatric doxycycline dosing is weight-based at 2.2 mg/kg/dose. For most indications, the loading regimen on day 1 is 2.2 mg/kg/dose twice daily (BID), followed by 2.2 mg/kg/day as a single daily dose or divided BID for subsequent days. The maximum dose is 100 mg per administration (200 mg/day). For tick-borne illnesses and certain serious infections, the full BID dosing is continued throughout the treatment course.
Is Doxycycline Safe for Young Children?
The historical concern about doxycycline causing permanent tooth staining in children under 8 years has been largely dispelled by modern evidence. Studies by Todd et al. (2015) and Lochary et al. (1998) demonstrated no visible dental staining in children treated with doxycycline. The AAP updated its guidance in 2020, confirming that doxycycline can be used safely in children of any age for short courses (≤21 days). Unlike older tetracyclines (tetracycline, oxytetracycline), doxycycline binds calcium less avidly and reversibly, explaining the absence of permanent dental effects.
🔑 Clinical Pearls
- Never delay doxycycline for suspected RMSF. Fatality rates increase dramatically when treatment is started after day 5 of illness. Empiric treatment should begin immediately upon clinical suspicion — do not wait for serology.
- For Lyme disease, doxycycline is preferred over amoxicillin in patients ≥8 years because it also covers potential Anaplasma co-infection from Ixodes ticks.
- Doxycycline is one of few antibiotics whose absorption is NOT significantly impaired by food (unlike tetracycline). Taking with food is recommended to reduce GI side effects.
- However, divalent and trivalent cations (Ca²⁺, Mg²⁺, Fe²⁺/³⁺, Al³⁺) DO reduce absorption — separate from dairy, antacids, and iron supplements by 2 hours.
- For acne, subantimicrobial dosing (40 mg modified-release daily) is an option in adolescents to reduce antibiotic resistance selection pressure.
- Esophageal ulceration is a recognized side effect — patients should take doxycycline with a full glass of water and remain upright for 30 minutes.
Indications and Duration
| Indication | Dose | Duration |
|---|---|---|
| General infections | 2.2 mg/kg/dose BID (day 1), then QD–BID | Varies by infection |
| RMSF | 2.2 mg/kg/dose BID | 5–7 days (≥3 days after defervescence) |
| Lyme disease (early) | 2.2 mg/kg/dose BID | 10–21 days |
| CAP (atypical) | 2.2 mg/kg/dose BID | 5–10 days |
| Acne | 1–2 mg/kg/day | 6–12 weeks typical |
| Malaria prophylaxis | 2.2 mg/kg/day QD | 1–2 days pre-travel through 4 weeks post |
| Anthrax PEP | 2.2 mg/kg/dose BID | 60 days |
Key References
- AAP Committee on Infectious Diseases. Red Book: 2021–2024 Report of the Committee on Infectious Diseases. 32nd ed. American Academy of Pediatrics; 2021.
- Todd SR, Dahlgren FS, Traeger MS, et al. No visible dental staining in children treated with doxycycline for suspected Rocky Mountain Spotted Fever. J Pediatr. 2015;166(5):1246–1251.
- Lochary ME, Lockhart PB, Williams WT. Doxycycline and staining of permanent teeth. Pediatr Infect Dis J. 1998;17(5):429–431.
- Biggs HM, Behravesh CB, Bradley KK, et al. Diagnosis and management of tickborne rickettsial diseases. MMWR Recomm Rep. 2016;65(RR-2):1–44.
Formula last verified: February 2026