How many doxycycline doses should be taken after a tick bite? - briefly
« При профилактике болезни Лайма после укуса клеща назначается доксициклин 200 мг один раз в сутки в течение 10‑14 дней, при начале терапии не позже 72 часов после контакта. »
How many doxycycline doses should be taken after a tick bite? - in detail
A single oral dose of 200 mg doxycycline administered within 72 hours of tick removal constitutes the standard prophylactic regimen for most adult patients at risk of Lyme disease. The recommendation applies when the tick is identified as an adult or nymphal Ixodes species, has been attached for at least 36 hours, and the bite occurred in a region where the incidence of infection exceeds 1 case per 10 000 persons‑years. The dose should be taken on an empty stomach to maximize absorption; food may reduce bioavailability.
For children weighing less than 45 kg, the appropriate dose is 4.4 mg per kilogram of body weight, not exceeding a total of 200 mg. The pediatric regimen must be administered under medical supervision, with attention to potential gastrointestinal upset and photosensitivity.
Pregnant or lactating individuals should avoid doxycycline because of teratogenic risk and possible effects on the infant. Alternative agents, such as amoxicillin 500 mg three times daily for 20 days, may be employed when doxycycline is contraindicated, though efficacy data for prophylaxis are less robust.
If the bite does not meet the high‑risk criteria—short attachment time, immature tick, or exposure in a low‑incidence area—routine prophylaxis is not indicated. In such cases, clinicians should advise patients to monitor for early signs of infection (erythema migrans, fever, arthralgia) and seek prompt evaluation if symptoms develop.
Adverse effects commonly observed with a single dose include mild nausea, abdominal discomfort, and transient photosensitivity. Severe reactions such as esophageal ulceration or hypersensitivity are rare with one‑time administration but warrant immediate medical attention if they occur.
In summary, the prophylactic protocol consists of:
- 200 mg doxycycline for adults (or 4.4 mg/kg for children <45 kg) within 72 hours of an attached tick meeting high‑risk criteria.
- Alternative 20‑day amoxicillin course for patients unable to receive doxycycline.
- Monitoring for adverse reactions and early disease manifestations when prophylaxis is not administered.