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:

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

  • Tony Michaels
    06/17/2019 (7:38 pm)

    Tony Michaels

    Hi there – I found what I believe to be a male Lone Star tick on my waist this past Saturday afternoon. I am basing that assumption that it was a male Lone Star tick on photographic comparisons I have made between the tick I removed and various photos I have viewed on-line. I am not certain if the tick attached itself this past Friday afternoon while on a golf course or while I was in my backyard Saturday morning/afternoon. Based on the timeline, I believe the maximum time it could have been attached was 30 hours while the minimum time would be 5 hours. The tick didn’t seem to be engorged and I have saved it in a zip-lock bag. I phoned my GP earlier to get his feedback on what if any preventative actions I should take to prevent acquiring tick borne illness. He prescribed a single dose of antibiotic as a prophylactic treatment (which I believe to be is 2x 100 mg’s pills of doxycycline). While perusing various websites today to learn and research as much as I can about ticks and the diseases they spread, it appears to me that the Lone Star tick isn’t a primary Lyme Disease carrier but does transmit several other potential sinister illnesses. I guess my question is should I even bother to take the doxycycline or just wait it out to see if symptoms develop. Based on some of the posts above, it looks as though you would lean on not taking it. Sorry for the long winded note, but I am just trying to make an educated decision regarding this – Thank you so much in advance for any advice you might give.

    • Dr. Daniel Cameron
      06/18/2019 (4:55 am)

      Your question reflects the uncertainty. The single 200 mg dose of doxycycline advised does not apply to the lone star tick. I need to weigh the pros and cons of watching vs a 3 to 4 week course of treatment. I follow my patient whether I treat or not.

  • J Hemingway
    05/16/2019 (12:00 pm)

    Hi Dr. Cameron, former nurse with a deer tick bite yesterday. Unfortunately, I did not recognize it as a tick and it was there at least 3-4 days and was engorged when I removed. I am in NC. Frustrating afternoon of going to urgent care and making multiple calls to practitioners and pharmacists who could not offer or offered conflicting advice. The young PA (from NJ) at urgent care subscribes to the single dose doxy. Thankfully, while frantically researching in the waiting room, I came across the ILADS site. I showed it to the PA and asked to call (to clarify if the 20 day doxy was prophylactic or once symptoms appear). He had “no time” for this. I insisted on a 20 day script and called ILADS after leaving. They could not provide info. Or clarification. I sat there with the docy in my hand and thought well…I think I should take this. My nurse friend and I decided I should do the 200 mg “loading dose” yesterday, and now will continue with 100mg BID. I feel completely alone in this and am very disappointed, yet agai , in the lack of knowledge/awareness among physicians…particularly in an endemic area such as this ?! (I am from Canada). Please, Dr. Cameron, could you confirm that I am doing the right thing at this point ? (doxy for 20 days seems like a long time…yikes) In adfition, I don’t believe they test the ticks here in NC (PA did not know, nor did he call to find out).My entomologist (retired) friend here said to forget the testing of the tick. As far as testing myself, it appears there is controversy over the accuracy of those results as well….and which type and at what stage they should be done?? Do you recommend any testing? What is to be done after the 20 day prophylaxis? Thanks so much in advance, for your time and reply. Janet H.

  • Dan
    05/11/2019 (10:46 pm)

    I noticed a bullseye shaped bruise on my leg at the end of April but never noticed anything on me or felt a bite. The mark was about an inch across. I went to a doctor and they gave me the single dose of doxycycline incase it was a tick bite. The mark never grew and faded like any normal bruise. I never had any symptoms of lyme and still dont it has been 3 weeks now. Is there a chance the mark was not tick or lyme related? It kind of felt like a bruise when touched. It had a small red mark at the center. Could something else have bitten me? Just wondering if I should have a follow up for lyme even though I have had no symptoms?

    • Dr. Daniel Cameron
      05/13/2019 (12:33 am)

      The CDC set 2 inches in diameter as a guideline. Rashes under 2 inches can come from other causes including a bruise. I am not a fan of a one time single 200 mg dose of doxycycline. I would rather follow closely or treat at least 3 weeks. You can see the rationale in ILADS guidelines at

        04/21/2020 (7:33 am)

        What exactly is the downside of taking the dose if it might prevent infection?

        • Dr. Daniel Cameron
          04/22/2020 (1:24 pm)

          Some patients develop complications of Lyme disease. The single 200 mg dose of doxycycline may prevent the rash but not the complications e.g., Lyme encephalopathy. The single dose may lead to a negative test with not treat the illness.

          • Alex
            07/14/2020 (7:50 am)

            My wife had the single dose of Doxycycline and developed a 1 inch (uniform, not bullseye) rash at the bite which went away. No other symptoms. I’m afraid that we just stopped the rash and not the disease. It’s now a month since the bite, is it too late to do a 20-day additional Doxycycline prophylaxis?

          • Dr. Daniel Cameron
            07/15/2020 (7:07 am)

            I share your concerns that the single dose of doxycycline may have interfered with the rash.

          • You will have to work with your doctor.
  • Janice
    05/08/2019 (7:39 pm)

    Today I removed an embedded female nymph deer tick which was on me 12-20 hours I think
    I took it to the local health department and the tester said it did not look engorged – I will have the test results in 3 days.

    In early 1990’s I had severe late stage Lyme with
    Neurological , arthritic and cardiac symptoms and ended up doing over 3 months of rocephin.

    Because of the previous severe problem,should I start antibiotics now? Wait 3 days? If the health department says it is not engorged is that a very
    Definitive diagnosis? They tests for Lyme and Babesiosis only and they said about 20% risk factor

    My GP had suggested taking a Westen blot and Elisa antibody test in a few weeks but could that be too late ? I live in Connecticut/land of Lyme !
    Thank you so much Dr. Cameron for helping with this devastating disease.

    • Dr. Daniel Cameron
      05/09/2019 (11:31 am)

      Thanks for sharing a few of the unresolved issues following a tick bite. The 24 to 36 hour window before infection was initially based on a mouse model and then only of the spirochete. We now know that there are tick borne pathogens that are transmitted sooner. The tick can test negative if damaged during shipping or if your blood interfered with the testing. i have to had to weigh the risks and benefit of treatment for each patient given the limited research evidence.

  • Ben Wildes
    01/31/2019 (9:03 pm)

    I was given a single dose doxycycline treatment for tick bite at a walk-in clinic. Weeks later I went back because I felt like I had symptoms of Lyme. The doctor there said that they don’t do follow-up for lyme, and that I would have to find someone else. I was sick everyday for a few more weeks until I could convince another doctor to give me 20 days of doxycycline. I finally got better and I’m okay now. Do not trust the single-dose treatment.

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