When to take doxycycline after a tick bite? - briefly
Start doxycycline as soon as possible, preferably within 72 hours of the bite, if Lyme disease is suspected. If the tick was attached for at least 36 hours and the regional infection prevalence exceeds 20 %, a single 200 mg dose is recommended.
When to take doxycycline after a tick bite? - in detail
Doxycycline is the preferred prophylactic antibiotic for preventing Lyme disease after a confirmed tick attachment. The medication should be started as soon as possible, ideally within 72 hours of removing the tick. Evidence shows that initiating therapy within this window reduces the risk of infection to less than 2 percent in endemic areas.
The standard regimen consists of a single 200 mg dose taken orally. No additional doses are required for prophylaxis, provided that the patient meets all of the following criteria:
- The tick is identified as an adult or nymphal Ixodes species.
- The tick has been attached for ≥ 36 hours, based on engorgement assessment.
- The exposure occurred in a region where the incidence of Lyme disease exceeds 20 cases per 100 000 persons per year.
- The patient is not allergic to tetracyclines, is not pregnant, and does not have severe liver disease.
- The patient is older than eight years and weighs at least 15 kg.
If any of these conditions are not met, observation for early symptoms (erythema migrans, fever, headache, fatigue) is recommended instead of immediate treatment. Should symptoms develop, a full therapeutic course of doxycycline (100 mg twice daily for 10–14 days) is indicated.
Adverse effects are generally mild and include gastrointestinal upset and photosensitivity. Patients should avoid excessive sun exposure and take the dose with a full glass of water to reduce esophageal irritation.
In summary, administer a single 200 mg oral dose of doxycycline within three days of a confirmed tick bite, provided the bite meets established risk criteria. Prompt treatment is the most effective strategy for preventing Lyme disease in high‑risk exposures.