How much Unidox should be taken after a tick bite? - briefly
A single 200 mg dose of Unidox (equivalent to two 100 mg tablets) should be taken once, as soon as possible and no later than 72 hours after the bite. This regimen is the standard prophylaxis recommended to prevent Lyme disease.
How much Unidox should be taken after a tick bite? - in detail
Unidox (doxycycline) is the recommended antimicrobial for prophylaxis after a tick bite that may transmit Lyme disease. The standard adult dose is 200 mg taken orally once, within 72 hours of removal of the attached tick. The single dose should be swallowed with a full glass of water; food does not affect absorption significantly, but avoid dairy products within two hours to reduce chelation.
For children weighing less than 45 kg (approximately 99 lb), the dose is adjusted to 4 mg per kilogram of body weight, not exceeding a total of 200 mg. The pediatric dose is also administered as a single oral dose within the same 72‑hour window. Infants under eight weeks of age are generally not given doxycycline because of the risk of tooth discoloration and bone growth inhibition; alternative prophylaxis should be considered.
Key considerations:
- The bite must be from a tick identified as Ixodes scapularis or Ixodes pacificus in regions where Lyme disease is endemic.
- The tick should have been attached for at least 36 hours, as shorter attachment periods carry a lower transmission risk.
- If the patient has a known allergy to tetracyclines, contraindications, or is pregnant, doxycycline is unsuitable; alternative antibiotics such as amoxicillin may be prescribed.
- A single dose is sufficient for prophylaxis; extended courses are reserved for confirmed infection or other indications.
Adverse effects are generally mild and may include gastrointestinal upset, photosensitivity, and temporary discoloration of teeth in children older than eight weeks. Patients should be advised to stay hydrated and protect skin from excessive sun exposure during the next 48 hours.
If any signs of early Lyme disease develop—erythema migrans, fever, headache, fatigue—prompt medical evaluation is required, and a full therapeutic course of doxycycline (100 mg twice daily for 10‑21 days) should be initiated.