Single Dose Antibiotic Treatment of Acute Watery Diarrhea, Rifaximin Versus Azithromycin, With Loperamide Adjunct

What this study involves

The registry does not currently label this study as recruiting. Ask about its status before planning a screening visit.

Study type

Interventional

Phase

Phase 4

Age range

18 years - 60 years

Sex eligible

All sexes

Healthy volunteers

Not accepted

Participants

128 Actual

These are starting points, not an eligibility decision. The research team must review the full requirements.

About the research

The purpose of this study is to compare a single dose of rifaximin with loperamide to the current standard approach of single dose azithromycin with loperamide for the treatment of acute watery traveler's diarrhea (TD).

The study requires 1) taking a single dose antibiotic plus loperamide to treat TD, 2) providing blood and stool samples at different time points to evaluate infection and immune responses, 3) completing a daily symptom diary following treatment, 4) being seen by the study doctor to monitor illness and recovery, and 5) completing a brief electronic questionnaire at 3 months.

Participants will be randomly assigned to one of the two treatment groups. The two groups are 1) rifaximin 550 mg as a single dose with loperamide or 2) azithromycin 500 mg as a single dose with loperamide. Both groups will take the antibiotic dose with 4 mg of loperamide. Participants are provided additional loperamide with instructions that they may take a 2 mg after continued diarrheal stools up to a maximum of 8 mg per day as needed.

Who may be able to participate?

The list below is the sponsor’s full registry wording. It can include conditions, prior treatment, test results and other requirements. A match in search does not mean you qualify.

Inclusion Criteria:

1. Active duty military, 18-60 years old
2. Presence of acute watery diarrhea (3 or more loose/liquid stools in 24 hours or 2 loose/liquid stools in 24 hours and associated symptoms such as nausea, vomiting, abdominal cramps or tenesmus) lasting \<96 hours in duration that impacts function in activities and/or performance of primary duties. Refer to recruitment decision tree below.
3. Eligible for ambulatory management. (Note: Ambulatory management in this study means that the patient can be treated on an outpatient basis to include up to 23 hours of medical observation and IV therapies.)
4. Able to comply with follow-up procedures.
5. Will remain in country for at least 7 days or an assurance that follow-up can be arranged elsewhere.

Exclusion Criteria:

1. Allergy to rifamycins, macrolides, or loperamide (not including mild gastrointestinal upset).
2. Antibiotic therapy in the 72 hours prior to presentation (excluding malaria prophylaxis with mefloquine, malarone, chloroquine/proguanil, tafenoquine, or doxycycline).
3. Concomitant medications with known drug-drug interactions with any of the study drugs (includes theophylline, digoxin, warfarin, chloroquine and hydroxychloroquine).
4. Current or history of liver disease or other serious health conditions based on review by study physician.
5. Acute dysentery and/or febrile illness (temperature \> 100.4°F \[38.1°C\]).
6. Presence of symptoms \>96 hours prior to initiating treatment.
7. Use of \>4 mg loperamide or use of any amount of loperamide for greater than 24 hours prior to enrollment. Prior use of bismuth subsalicylate or other anti-diarrheal, non-antibiotic therapy in the 48 hours prior to enrollment.
8. Positive pregnancy test at presentation (unknown effects with rifaximin). All female participants will be administered a urine pregnancy test prior to enrollment.
9. Previously screened or randomized in this study.

Treatment, groups and participation

The registry may describe treatments and study duration without a complete visit calendar. Ask the study team for the exact schedule, procedures, risks, costs and alternatives. Keep your usual care plan unless your treating clinician tells you otherwise.

Assignment

Random assignment

Masking

Quadruple masked

What researchers are measuring

Outcome measures describe what is being studied. They are not proof that a treatment works.

Primary measures

Secondary measures

Research locations (4)

The overall study status and a local site’s status can differ. Confirm that location’s availability before traveling.

4 locations

Study team and timeline

Lead sponsor

Henry M. Jackson Foundation for the Advancement of Military Medicine

Study start

Oct 28, 2022 Actual

Primary completion

Jun 29, 2025 Actual

Study completion

2026-12 Estimated

First posted

Jan 10, 2023 Actual

Last updated

Nov 10, 2026 Actual

Official study contacts

No central contact is listed. Check the locations and the official record.