What is the dose of doxycycline (Doxycycline) for prophylaxis after a tick bite?

From the Guidelines

The recommended prophylactic dose of doxycycline following a tick bite is a single 200 mg dose taken orally within 72 hours of tick removal, as indicated for high-risk tick bites in adults and 4.4 mg/kg (up to a maximum dose of 200 mg) for children. This prophylaxis is specifically indicated for high-risk tick bites, such as those from Ixodes scapularis (deer tick) in areas where Lyme disease is endemic, when the tick has been attached for at least 36 hours, and when prophylaxis can be started within 72 hours of tick removal 1. The single dose approach works because doxycycline has a long half-life and is effective at killing Borrelia burgdorferi (the bacteria causing Lyme disease) during its early dissemination.

Key Considerations

• The decision to administer prophylactic doxycycline should be based on the risk assessment of the tick bite, considering factors such as the tick species, the duration of attachment, and the endemicity of Lyme disease in the area 1.
• Patients should be advised to monitor for symptoms such as rash, fever, or joint pain for 30 days after the bite, even after receiving prophylaxis.
• Doxycycline should be avoided in pregnant women and children under 8 years old due to potential effects on bone development and tooth discoloration.

High-Risk Tick Bites

• A tick bite is considered high-risk if it meets specific criteria, including being from an identified Ixodes spp. vector species, occurring in a highly endemic area, and the tick being attached for ≥36 hours 1.
• For bites that cannot be classified with a high level of certainty as high-risk, a wait-and-watch approach is recommended 1.

Prophylaxis Administration

• Prophylactic antibiotic therapy should be given only to adults and children within 72 hours of removal of an identified high-risk tick bite 1.
• The administration of doxycycline as a single oral dose is recommended over observation for high-risk Ixodes spp. bites in all age groups 1.

From the FDA Drug Label

For the prophylaxis of malaria: For adults, the recommended dose is 100 mg daily. Inhalational anthrax (post-exposure): ADULTS: 100 mg of doxycycline, by mouth, twice a day for 60 days.

The dose of doxycycline for tick bite prophylaxis is not explicitly stated in the provided drug label. However, based on the available information, the recommended dose for prophylaxis in other conditions is 100 mg daily for adults.

• Doxycycline dose: 100 mg daily for adults (as seen in malaria prophylaxis)
• Note: The provided label does not directly address tick bite prophylaxis, and therefore, this answer is inferred from other prophylaxis regimens 2.

From the Research

Tick Bite Doxycycline Prophylaxis Dose

• The dose of doxycycline for prophylaxis after a tick bite is typically 200 mg orally, as a single dose 3, 4, 5.
• This dose has been shown to be effective in preventing Lyme disease in both North America and Europe 3, 4.
• A study published in 2021 found that a single dose of 200 mg doxycycline reduced the risk of Lyme borreliosis by 67% compared to no treatment 4.
• Another study published in 2021 found that the pooled rate of unfavorable events in persons receiving a single dose of 200 mg doxycycline was 0.4%, compared to 2.2% in the control group 5.
• It is recommended that prophylactic treatment be delivered promptly after potentially infectious ticks are removed from patients, as delaying treatment by 24 hours or more may reduce its effectiveness 6.

Efficacy of Doxycycline Prophylaxis

• The efficacy of doxycycline prophylaxis in preventing Lyme disease has been demonstrated in several studies 7, 3, 4, 5.
• A study published in 2008 found that doxycycline was effective in preventing Lyme disease in patients who received treatment within 72 hours of a tick bite 3.
• Another study published in 2021 found that the pooled risk ratio for the rates of unfavorable events in patients who received doxycycline prophylaxis was 0.38, compared to the control group 5.

Timing of Prophylactic Treatment

• The timing of prophylactic treatment is critical, as delaying treatment by 24 hours or more may reduce its effectiveness 6.
• A study published in 2012 found that prophylactic treatment with doxycycline was most effective when delivered on the day of tick removal, and that delaying treatment by 24 hours or more reduced its effectiveness 6.