Single dose doxycycline for treatment of tick bite only prevents Lyme disease rash

Man taking doxycycline which will only prevent Lyme disease rash.

In a review entitled “Lyme Disease: Emergency Department Considerations,” Applegren et al. recommend using a one-time, single dose of doxycycline for the prophylactic treatment of a tick bite, [1] despite the fact that there has been only one study exploring the effectiveness of such a limited dosage. The article also neglects to mention that there are doctors who take a different approach and advise against a one-time, single dose. [3]

In the article, the authors reference the 2006 Infectious Diseases Society of America (IDSA) guidelines when making their recommendation that “individuals be treated with a single dose of doxycycline (4 mg/kg in children ≥8 years of age to a maximum 200 mg and 200 mg in adults)”. [1]

Their recommendation applies only to patients meeting the following criteria, “(1) the attached tick is clearly identified as a nymph or adult I. scapularis; (2) the tick has been attached ≥36 hours; (3) local infection rates of ticks with B. burgdorferi is ≥20%; and (4) there are no contraindications to doxycycline.” [2]

The authors fail to mention that the IDSA single dose of doxycycline approach is based on one study, which only found a reduction in the number of erythema migrans (EM) rashes.

“A study by Nadelman et al. found that patients treated with a single dose of doxycycline developed EM manifestation at a lower rate than the placebo group (0.4% compared to 3.2%, respectively),” according to Applegren. 

The review also does not mention the evidence, as put forth by the International Lyme and Associated Diseases Society (ILADS), which finds that a single dose is ineffective in warding off Lyme disease. Such evidence was easily accessible via open access, peer-reviewed journals in PubMed [3], the Journal’s website[4], and the National Guideline Clearing House. [5]

ILADS 2014 guidelines used the Grading of Recommendations Assessment, Development and Evaluation (GRADE) system to conclude that the evidence for a single, 200 mg dose of doxycycline was “sparse, coming from a single study with few events, and, thus, imprecise.” [3]

There were only 9 EM rashes in the Nadelman study. Nadelman and colleagues were able to reduce the number of rashes from eight to one by prescribing a single 200 mg dose of doxycycline. The “p” value was barely significant at 0.04.

The IDSA guidelines adopted the single, 200 mg dose of doxycycline despite the fact that 3 previous prophylactic antibiotic trials for a tick bite had failed.

Nadelman’s study had several other limitations:

  1. It was not designed to detect Lyme disease if the rash were absent.
  2. The 6-week observation period was not designed to detect chronic or late manifestations of Lyme disease.
  3. It was not designed to assess whether a single dose of doxycycline might be effective for preventing other tick-borne illnesses such as Ehrlichia, Anaplasmosis, or Borrelia miyamotoi.

Today, patients expect to be informed of their treatment options. The recent review in the Journal of Emergency Medicine [1] would have been stronger if the authors had disclosed the evidence against using a single, 200 mg dose of doxycycline for prophylactic treatment of a tick bite.

Updated: August 29, 2022

  1. Applegren ND, Kraus CK. Lyme Disease: Emergency Department Considerations. J Emerg Med, (2017).
  2. Wormser GP, Dattwyler RJ, Shapiro ED et al. The clinical assessment, treatment, and prevention of lyme disease, human granulocytic anaplasmosis, and babesiosis: clinical practice guidelines by the Infectious Diseases Society of America. Clin Infect Dis, 43(9), 1089-1134 (2006).
  3. Cameron DJ, Johnson LB, Maloney EL. Evidence assessments and guideline recommendations in Lyme disease: the clinical management of known tick bites, erythema migrans rashes and persistent disease. Expert Rev Anti Infect Ther, 1-33 (2014).
  4. Cameron DJ, Johnson LB, Maloney EL. Evidence assessments and guideline recommendations in Lyme disease: the clinical management of known tick bites, erythema migrans rashes and persistent disease from Expert Review of Anti-infective Therapy 2014 at
  5. Evidence assessments and guideline recommendations in Lyme disease: the clinical management of known tick bites, erythema migrans rashes and persistent disease. National Guideline Clearinghouse. Agency for Health Care Research and Quality. Available from:

53 Replies to "Single dose doxycycline for treatment of tick bite only prevents Lyme disease rash"

  • Carol Hall
    11/11/2020 (9:13 am)

    Went hiking on Thursday. A deer tick was found feeding on my husband Saturday. While taking it off the skin it disintegrated. I then had nothing to test. 😢 Started a ten day course 100 mg doxycycline, 1 BID. Would you recommend to continue the antibiotic for the full 3 or 4 weeks? He is on his 4th day of antibiotics. He is handleing the antibiotic just fine and with all the unknown about trasmission from a deer tick ( which may or may not affect your quality of life) would your professional opinion be to continue longer? If so how much longer?

    • Dr. Daniel Cameron
      11/11/2020 (10:06 am)

      I prefer at least 3 to 4 weeks for a tick bite for prophylactic treatment with a reevaluation. Other doctors disagree.

      • Cari
        07/08/2021 (7:46 am)

        I got bit by a tick on my stomach 2 weeks ago. I got the one dose doxycyclone 6 days later. It’s now been a week and 2 days and the rash is bigger. Should I go back to the doc to get on more doxy?

        • Dr. Daniel Cameron
          07/08/2021 (9:26 am)

          I have been opposed to a single dose of doxycycline for a tick bite and not for a rash. Some small rashes reflect irritation from the tick. I would not ignore the rash. I would typically advise consulting a doctor.

  • Justin
    10/28/2020 (2:14 pm)

    Found an adult deer tick on my leg on Monday, 10/26, after feeling pain at the bite location. Red ring around the bite, tick slightly engorged. My guess is it was there for 24-48 hours. Pulled it off, called the doc, and was prescribed the single dose doxy. Took it that day. The ring has shrunk and I feel fine, but after looking into further, it seems that the single dose is not the optimal course of treatment. My question is, will having taken the doxy on Monday, waiting, and taking it again (provided I can convince my doc to give the prescription) be an effective treatment? Thank you.

    • Dr. Daniel Cameron
      10/28/2020 (6:41 pm)

      The risk of Lyme from a tick bite is low but it can happen. I review the risk and benefits of a 3 week course. I typically find a course of doxycycline effective for those I have treated.

  • Alan
    10/24/2020 (5:37 am)

    Just found a tick stuck to my stomach and pulled it off. So I’m looking for tick bite info and looking through your blog. I simply don’t understand why the medical profession can’t come up with better answers. Why don’t doctors just perscribe 100 mg doxycycline twice daily for three weeks for any tick bites as a preliminary treatment pending diagnosis for Lyme disease. Heck, if you have pimples, dermatologists will perscribe doxycycline for months or longer. So, in some cases, doctors are so cautious that they worry about a single antibiotic in other cases they happily dose for long term.

  • Liss
    07/03/2020 (8:27 pm)

    Hello! My two, almost three year old, developed a EM Saturday morning. We went to pediatrician and they prescribed 2 weeks of amoxicillin, 250mg three times a day, for 14 days. We live in NC and don’t have knowledge but we have a dozen deer a day come into our driveway. They said it could be Lyme or STARI. Will this protocol work? Thank you for your assistance! Such a scary time!

    • Dr. Daniel Cameron
      07/04/2020 (7:30 am)

      Doctors differ regarding the length of treatment. I prefer 3 to 4 weeks of amoxicillin with follow-up before ending treatment to reduce the chances of chronic illness. That leaves the doctor responsible for weighing the benefits against the side effects. Amoxicillin does not work for other tick borne infections such as Anaplasmosis and Babesia. I don’t take care of children that age.

  • Veronica Dwyer
    06/27/2020 (5:28 pm)

    Hello. I a large expanding rash a few weeks ago. Went to minor care and was diagnosed with the largest ringworm ever seen by the doctor. Increasing fatigue and headaches caused me to seek a second opinion. I went to another Doctor who suspected Lyme prescribing a one dose 200 mg doxycycline but insurance company suggested 10 days 2×100 mg doxycycline. I am on the fourth day and still feeling miserable. Should I request the doxycycline prescription be longer than 10 days and is the antibiotic even working since I still feel terrible? After reading so much about one time dose not working I am afraid the 10 days isn’t enough.

    • Dr. Daniel Cameron
      06/27/2020 (6:17 pm)

      A single dose of doxycycline is only indicated for a tick bite and not a rash. I am opposed to a single dose. I favor a longer course of antibiotics and follow-before stopping. Call my office at 914 666 4665 if you have any questions.
      You can read more in the ILADS guidelines at

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