May 20, 2022

Are oral prophylactic antibiotics effective against Lyme disease?

The use of antibiotics for prophylaxis has been shown to be effective against Lyme disease, according to the results of a meta-analysis published in BMC infectious diseases.

Investigators searched PubMed, Embase, and the Cochrane Library for studies of patients who had no clinical signs of Lyme disease 72 hours after receiving a tick bite and who were assigned to the intervention group or a group of witnesses. Patients in the intervention groups received either a 10-day oral course of antibiotics, a single 200 mg dose of oral doxycycline, or topical antibiotic treatment with azithromycin. A random-effects model was used to calculate the pooled results and the relative risk for the rates of adverse events in patients in both groups.

Overall, the final analysis included 6 randomized controlled trials with a total of 3766 patients, 56 of whom had adverse events. It should be noted that only one event was disseminated Lyme disease while 55 were erythema migrans.

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Among patients in the intervention groups, the combined rate of adverse events was 0.4% (95% CI: 0.1-1.1; I2 = 55%) versus 2.2% (95% CI, 1.6-3.0: I2 = 5%) among those in the control groups. In addition, the combined relative risk was 0.38 (95% CI: 0.22-0.66; I2 = 0%).

Among the patients included in the 5 studies that evaluated the effects of oral prophylactic antibiotics, the combined rate of adverse events among those in the intervention and control groups was 0.2% (95% CI: 0.0 -1.0; I2 = 57%) and 2.5% (95% CI, 1.7-3.5; I2 = 0%, respectively, and the combined relative risk was 0.29 (95% CI: 0.15 to 0.57; I2 = 0%).

The combined risk ratio for patients who received a single 200 mg dose of doxycycline and those who received a 10-day course of oral antibiotics was 0.29 (95% CI, 0.14-0, 60; I2 = 0%) and 0.28 (95% CI, 0.05 to 1.67; I2 = 0%), respectively. Among patients who received topical antibiotics, the combined relative risk was 0.73 (95% CI, 0.25-2.08).

Study limitations included the small number of studies eligible for inclusion, the heterogeneity of tick species across study locations, and the use of erythema migrans as the primary endpoint for all included studies, which may have underestimated the true incidence of Lyme disease.

According to the researchers, “the available evidence supports the prophylactic use of antibiotics for the prevention of Lyme disease and the benefits of a single dose of doxycycline, but further confirmation is needed.”


Zhou G, Xu X, Zhang Y et al. Antibiotic prophylaxis for the prevention of Lyme disease after a tick bite: an updated systematic review and meta-analysis. BMC Infect Dis. 2021; 21 (1): 1141. doi: 10.1186 / s12879-021-06837-7.