Comparing Azithromycin and Doxycycline for treating Rocky Mountain Spotted Fever

Efficacy of Azithromycin Plus Doxycycline Compared to Doxycycline Plus Placebo in Patients With Rocky Mountain Spotted Fever in Hospital General de Mexicali of ISESALUD and Hospital General No. 30 Instituto Mexicano Del Seguro Social

Phase 3 Interventional Hospital General de Mexicali · NCT05398055

This study is testing if adding Azithromycin to Doxycycline can help hospitalized patients with Rocky Mountain Spotted Fever get better compared to just using Doxycycline with a placebo.

Quick facts

PhasePhase 3
Study typeInterventional
Enrollment86 (estimated)
Ages18 Years and up
SexAll
SponsorHospital General de Mexicali Academic / other
Locations1 site (Mexicali, Baja California)
Trial IDNCT05398055 on ClinicalTrials.gov

What this trial studies

This study aims to improve the treatment of Rocky Mountain Spotted Fever (RMSF) by comparing the efficacy of Azithromycin combined with Doxycycline against Doxycycline plus a placebo. RMSF is a serious infectious disease caused by Rickettsia rickettsii, which primarily affects the vascular system. The study will enroll hospitalized patients exhibiting symptoms of RMSF and relevant epidemiological factors. By introducing Azithromycin, a macrolide antibiotic, the researchers hope to enhance treatment outcomes for this potentially fatal disease.

Who should consider this trial

Good fit: Ideal candidates are hospitalized adults over 18 years old with suspected RMSF and specific symptoms.

Not a fit: Patients with other clinical suspicions, allergies to the study medications, or who are pregnant may not benefit from this study.

Why it matters

Potential benefit: If successful, this study could lead to more effective treatment options for patients suffering from Rocky Mountain Spotted Fever.

How similar studies have performed: While the approach of using Azithromycin in this context is novel, other studies have shown success with similar antibiotic strategies in treating rickettsial diseases.

Eligibility criteria

Show full inclusion / exclusion criteria
Inclusion Criteria:

* Any gender
* Over 18 years old
* hospitalized in the internal medicine service, emergency department or intensive care unit of Hospital General de Mexicali (ISESALUD) or Hospital General Zona No. 30 (IMSS) with suspicion of RMSF that present fever and 2 or more of the next symptoms: headache, myalgia, rash, nausea, pharyngeal hyperemia, vomiting, abdominal pain, neurological disorders.
* In addition to at least one of the next epidemiologycal fators: presence of vectors in areas of residence or endemic areas visited two weeks prior to the onset of symptoms, history of visiting or residing in areas with RMSF transmission in the last two weeks, existence of confirmed cases in the locality of origin, history of vector bite or contact with dogs in the two weeks.

Exclusion Criteria:

* Other clinical suspicion rather than RMSF
* History of allergy to doxycycline, azithromycin, bean starch or bovine gelatin.
* Not signing the informed consent
* Pregnancy.

Where this trial is running

Mexicali, Baja California

Study contacts

How to participate

  1. Review the eligibility criteria above with your treating physician.
  2. Visit the official trial page on ClinicalTrials.gov for the most current contact information and recruitment status.
  3. Contact the listed study coordinator or principal investigator to request pre-screening. Pre-screening is free and never obligates you to enroll.
Conditions Rocky Mountain Spotted FeverAzithromycinDoxycycline
Last reviewed 2026-06-13 by the Find a Trial editorial team. Information on this page is for educational purposes and is not medical advice. Always consult qualified healthcare professionals about clinical trial participation.