What should be injected if a tick bites? - briefly
Administer a single 200 mg dose of doxycycline within 72 hours of the bite, and verify that tetanus immunization is current.
What should be injected if a tick bites? - in detail
A prophylactic dose of doxycycline is the primary injection recommended after a tick bite when the attached tick is identified as a potential carrier of Borrelia burgdorferi (Lyme disease). The regimen consists of a single 200 mg oral dose administered within 72 hours of removal. This approach is supported by evidence that early antibiotic exposure reduces the incidence of erythema migrans and subsequent systemic manifestations.
If the bite occurs in an area where tick‑borne rickettsial diseases are prevalent (e.g., Rocky Mountain spotted fever), a single intramuscular dose of doxycycline (200 mg) may also be employed, with the same 72‑hour window for optimal efficacy. For patients with contraindications to tetracyclines—such as pregnancy, lactation, or known hypersensitivity—alternatives include a 5‑day course of amoxicillin (500 mg three times daily) or cefuroxime axetil (500 mg twice daily), though these are oral regimens rather than injections.
Tetanus prophylaxis should be assessed independently of the tick exposure. If the individual’s immunization status is uncertain or the wound is contaminated, a tetanus toxoid booster (0.5 mL intramuscularly) or, when indicated, tetanus immune globulin (250 IU intramuscularly) must be administered according to standard wound management guidelines.
In regions where rabies vectors include ticks—though rare—post‑exposure prophylaxis follows the standard rabies vaccination schedule: a series of four intramuscular injections (days 0, 3, 7, 14) of purified Vero cell rabies vaccine, with rabies immune globulin (20 IU/kg) infiltrated around the bite site at the initial visit.
Key considerations for the injection decision:
- Tick identification – species, attachment duration, and geographic prevalence of pathogens.
- Time elapsed – effectiveness of doxycycline declines after 72 hours.
- Patient factors – age, pregnancy status, drug allergies, immunization history.
- Local epidemiology – presence of Lyme disease, rickettsial infections, or other tick‑borne illnesses.
Monitoring after administration includes observation for allergic reactions at the injection site, assessment for signs of infection (fever, rash, arthralgia), and documentation of the prophylactic measure in the medical record. If symptoms develop despite prophylaxis, prompt diagnostic testing and therapeutic escalation are warranted.