6/30/23, 2:23 AM Tick Bite Pathway Feedback Search Clinical Topics Home Studies Tick Bite Tick Bite Disease Tick bite Trial question What is the role of prophylaxis with single-dose doxycycline after an Ixodes scapularis tick bite? Study design Multi-center Double blinded RCT Population Characteristics of study participants 47.0% female N = 482 53.0% male 482 patients (225 female, 257 male) Inclusion criteria: patients who an Ixodes scapularis tick removed from their bodies within the previous 72 hours Key exclusion criteria: clinical signs of Lyme disease at the time of enrollment, receipt of antibiotics effective against Borrelia burgdorferi, vaccination against Lyme disease Interventions N=235 doxycycline (two 100 mg capsules) N=247 placebo (two identical-appearing lactose capsules) Primary outcome Development of erythema migrans at site of tick bite https://web.pathway.md/studies/recWmK4sAaJx32nao 1/2 6/30/23, 2:23 AM Tick Bite Pathway 3.2 % 3.2 2.4 % 1.6 % Significant decrease 0.8 % NNT = 36 0.4 0.0 % Doxycycline Placebo Significant decrease in development of erythema migrans at the site of tick bite (0.4% vs. 3.2%; RR 0.13, 95% CI 0.01 to 0.25) Secondary outcomes No significant difference in acute viral-like illness without erythema migrans (0.4% vs. 0.8%; ARD -0.4, 95% CI -56.9 to 56.1) No significant difference in febrile episodes (2.1% vs. 1.6%; AD 0.5%, 95% CI -2.42 to 3.42) Safety outcomes No significant differences in abdominal discomfort, diarrhea, dizziness. Significant differences in adverse events, which were more common in patients receiving doxycycline (30.1% vs. 11.1%). Conclusion In patients who an Ixodes scapularis tick removed from their bodies within the previous 72 hours, doxycycline was superior to placebo with respect to development of erythema migrans at the site of tick bite. Reference R B Nadelman, J Nowakowski, D Fish et al. Prophylaxis with single-dose doxycycline for the prevention of Lyme disease after an Ixodes scapularis tick bite. N Engl J Med. 2001 Jul 12;345(2):79-84. Open reference URL https://web.pathway.md/studies/recWmK4sAaJx32nao 2/2