Does Azithromycin Gel Prevent Lyme Disease After a Tick Bite?
Bitten by a tick?
Can a topical gel prevent Lyme disease?
The answer may surprise you.
by Daniel J. Cameron, MD, MPH
A study published in The Lancet Infectious Diseases examined whether a topical antibiotic could prevent Lyme disease after a tick bite. The results were not as promising as many had hoped.
For a broader overview of prevention strategies, start here: Lyme disease prevention.
What the Study Found
In a double-blind, placebo-controlled clinical trial, investigators evaluated a 10% azithromycin gel applied after a tick bite.
In a post hoc analysis of 134 subjects:
- The gel prevented 6 erythema migrans (EM) rashes
- It delayed the onset of EM rashes by 33 and 51 days in 2 additional patients
At first glance, this may seem encouraging. However, these findings require careful interpretation.
What the Study Did Not Show
The trial did not demonstrate that azithromycin gel could prevent Lyme disease.
Instead, it showed only that:
- A small number of EM rashes were prevented
- Some rashes were delayed—not eliminated
This distinction is critical. Preventing a rash is not the same as preventing infection.
Why This Matters Clinically
There is understandable interest in a simple, topical treatment to prevent Lyme disease after a tick bite.
However, based on this trial:
- The benefit was limited
- The effect was inconsistent
- There was no clear prevention of Lyme disease
This means azithromycin gel cannot be relied upon as a preventive strategy.
What Should Patients Do After a Tick Bite?
Effective Lyme disease prevention requires a broader approach.
For guidance, see: Lyme disease prevention.
Key steps include:
- Prompt tick removal
- Monitoring for symptoms
- Clinical evaluation when appropriate
A single topical treatment is unlikely to replace these steps.
Common Sense Lyme Takeaway
It would be ideal to have a quick, reliable way to prevent Lyme disease after a tick bite.
But based on current evidence, azithromycin gel is not that solution.
Delaying a rash is not the same as preventing Lyme disease—and relying on it may provide false reassurance.
References:
- Schwameis M et al. Topical azithromycin for the prevention of Lyme borreliosis: a randomized, placebo-controlled, phase 3 trial. Lancet Infect Dis. 2016.
Dr. Daniel Cameron, MD, MPH
Lyme disease clinician with over 30 years of experience and past president of ILADS.
Symptoms • Testing • Coinfections • Recovery • Pediatric • Prevention
Thank you for this post, Dr Cameron. This was widely reported in the press as being a trial which showed that the gel had “promise” as a treatment for infected bites. As here: https://www.news-medical.net/news/20161220/Antibiotic-gel-shows-promise-in-preventing-onset-of-Lyme-borreliosis-following-tick-bite.aspx
It is a shame the gel failed to work
Is Azithromycin in tablet form affective to treat Lyme?
Oral Zithromax has been effective in most studies. Doxycycline beat Zithromax in on study my Massaroti in 1992.
Because the company making the gel was able to get special status from CDC, called QIDPb status, they get two tries at doing a stage III clinical trial such as this. So long as they have the money, they a redo to look only at the subgroup that showed some benefit. This worries me, because doing a placebo controlled study of high risk tick bites resembles Tuskegee to me: they are knowingly allowing the placebo group to get sick, in order to get a statistically more favorable outcome. Even if the gel helps a segment of people, there is no way for them to identify themselves in advance, so if it’s approved, everybody, not just the subgroup, will potentially use this, and forgo oral antibiotics. One of their medical advisors is Dr. Wormser. I think they might potentially raise the money because the product would be over the counter, this saving instance companies money they would have spent on doxycycline or Amoxicillin.
I also have concerns with trying to sell a cream based on subgroup analysis.