Could a shorter antibiotic course for lyme disease be just as effective?
NCT ID NCT03337932
First seen Jun 27, 2026 · Last updated Jun 27, 2026
Summary
This trial is testing whether a 7-day course of doxycycline works as well as the standard 14-day course for people with multiple erythema migrans, a sign of early Lyme disease. About 200 participants will be randomly assigned to one of the two treatment durations. Researchers will track symptoms and any new Lyme-related problems for up to a year to see if the shorter treatment is enough.
What this could mean
Our plain-language read of the trial. This is informational only, not medical advice or a prediction.
- Active substance
- doxycycline
- What this could lead to
- If successful, this could show that a 7-day course of doxycycline is just as effective as the standard 14-day course for treating multiple erythema migrans, potentially reducing antibiotic use and side effects.
- What could go wrong
- This is a relatively small trial (200 participants) and results may not apply to all Lyme disease cases. The study is still recruiting, so findings are preliminary and could show no significant difference between the two treatment durations.
This is an AI summary of the original study and may miss details. Read our disclaimer.
Study facts
What this study's own registry entry says, in plain language.
- Phase
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Not a phased trial
Phase numbers describe drug development. The registry uses this when they do not apply, as it does for trials of devices, procedures or behaviour changes, and for observational studies.
- Participants
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About 200 people
The number the study aims to enrol. It can still change while the study runs.
- Started
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May 2018
- Expected to finish
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Dec 2027
An estimate. End dates often move.
- Lead sponsor
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Other sponsor
The registry's catch-all category, for sponsors it does not file as a company, a government agency, or a research network.
Who can take part
This study's own entry requirements. Only the study team can say for certain whether you qualify.
- Ages
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18 years and older
- Sex
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Anyone
- Healthy volunteers
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Accepted
You do not need to have the condition being studied to take part.
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Copied word for word from the study's registry entry, so the wording is the study team's rather than ours.
Inclusion Criteria: • multiple erythema migrans Exclusion Criteria: * pregnancy or lactation * immunocompromised * serious adverse event to doxycycline * taking antibiotic with antiborrelial activity within 10 days * extracutaneous manifestations of lyme borreliosis
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Conditions
The condition(s) this trial relates to.
As listed by the trial registrant
The condition terms exactly as the trial's registrant entered them.
How to take part
Only the study team decides who joins. These are the ways to reach them.
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The places running it
1 site. The list below names each one and where it is.
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The official record
ClinicalTrials.gov lists the study team's own contact details, including names and phone numbers. We don't republish those.
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A doctor treating you
A doctor who knows your case can contact a study site on your behalf, and can tell you whether this study is worth pursuing at all.
Contacts and locations
Locations
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University Medical center Ljubljana
RECRUITINGLjubljana, Slovenia