Tick bites: post-exposure prophylaxis to prevent Lyme disease
Clinical basis & sources
Sources used
- Minor Ailments PrescribingOntario College of Pharmacists · 2026
- Ontario Regulation 256/24: GeneralGovernment of Ontario · 2026
- Minor Ailments: Drug Classes and Specified DrugsOntario College of Pharmacists · 2026
- Executive Officer Notice: Update to Funding for Minor Ailment Services in Ontario Pharmacies (Effective July 1, 2026)Government of Ontario · 2026-05-19
- 2020 Guidelines for the Prevention, Diagnosis and Treatment of Lyme DiseaseInfectious Diseases Society of America, American Academy of Neurology, and American College of Rheumatology · 2020
- Guidance for Clinicians: Recommendations for Patients after a Tick BiteCenters for Disease Control and Prevention · 2022
- Community pharmacist prescribing of antimicrobials: A systematic review from an antimicrobial stewardship perspectiveCanadian Pharmacists Journal · 2021
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Allowable drugs under Schedule 4 (1)
Drugs an Ontario pharmacist may prescribe for Tick bites: post-exposure prophylaxis to prevent Lyme disease under O. Reg. 256/24, Schedule 4. Choice still depends on the assessment, contraindications, allergies, and product availability — this is the eligible list, not a recommendation.
- Doxycycline
Symptoms this assessment screens
- Tick bite occurred and tick has been removed or can be removed safely now
- Tick was removed within the past 72 hours
- Bite occurred in a higher-risk area where blacklegged ticks have been identified
- Tick was likely attached for 24 hours or more or appeared engorged
- Patient has no Lyme-compatible symptoms after the tick bite
- Doxycycline is safe after allergy, pregnancy/lactation, interaction, and patient-specific review
Red flags — any positive means refer
- Expanding erythema migrans or bull's-eye rash, fever, chills, headache, stiff neck, fatigue, appetite change, muscle/joint aches, joint swelling, or swollen lymph nodes
- Facial palsy, severe headache or neck stiffness, confusion, palpitations, chest pain, shortness of breath, fainting, migratory joint pain, or marked joint swelling
- Rapidly spreading redness, warmth, pus, severe bite-site pain, fever, or retained tick parts requiring a procedure
- Tick removed more than 72 hours ago, attached under 24 hours, bite not in a higher-risk area, tick clearly not blacklegged/Ixodes, or exposure location cannot support prophylaxis
- Doxycycline allergy, serious prior reaction, clinically significant interaction, or another patient-specific safety concern that makes doxycycline unsafe
- Complex immunocompromise, multiple concerning bites, uncertain assessment, patient cannot understand monitoring advice, or pharmacist is not confident the case is minor
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