Azithromycin for Travelers' Diarrhea
Azithromycin is the antibiotic travellers carry to treat moderate or severe travelers' diarrhea if it strikes, not to prevent it. A single 1,000 mg dose, or 500 mg daily for three days, usually shortens the illness from days to about a day. It is now preferred over ciprofloxacin, especially in South and Southeast Asia where resistant bacteria are common.
Also known as: Zithromax, Z-Pak
Availability
Prescription only (carried, taken if needed)
Start
Not taken in advance; carried for use if symptoms start
Course
One 1,000 mg dose, or 500 mg daily for 3 days
Typical cost
Generic, usually $10–$25 for a course
Who needs it
- Travellers to high-risk regions: most of South and Southeast Asia, Africa, Central and South America, and Mexico
- Anyone whose trip would be seriously disrupted by two or three days of illness: tight itineraries, remote treks, business travel
- Travellers with conditions that make dehydration more dangerous, such as diabetes, inflammatory bowel disease or heart disease
- Travellers to South and Southeast Asia specifically, where Campylobacter resistant to ciprofloxacin is widespread
How it works
Azithromycin is a macrolide antibiotic that stops bacteria from making proteins, killing the common causes of travelers' diarrhea such as E. coli, Campylobacter, Shigella and Salmonella. A single large dose stays active in the gut for days, which is why one dose is often enough.
How it's taken
The standard CDC summary. Your pharmacist confirms the schedule for your itinerary and health history.
- 1Carry it; do not take it in advance. Antibiotics are not recommended to prevent travelers' diarrhea because of side effects and resistance
- 2Use it for moderate diarrhea (interferes with plans) or severe diarrhea (incapacitating, or with fever or blood). Mild cases need only fluids and, if wanted, loperamide
- 3Standard adult regimens: one 1,000 mg dose, or 500 mg once daily for 3 days. Your pharmacist confirms which suits you
- 4Loperamide (Imodium) can be added for symptom relief when there is no fever or blood in the stool. Never rely on loperamide alone for dysentery
- 5Rehydrate: oral rehydration salts or clean fluids with some salt and sugar, especially for children and older travellers
- 6Seek medical care if you have a high fever, bloody stools that do not improve within a day of treatment, signs of dehydration, or symptoms lasting more than a few days
Side effects and who should not take it
Common side effects
- Nausea, stomach cramps or additional loose stools, more likely with the single 1,000 mg dose
- Rarely, a rash or a temporary hearing change
- Can affect heart rhythm (QT prolongation) in people with certain heart conditions or on interacting medications
Talk to the pharmacist first if
- People with a known allergy to azithromycin, erythromycin or clarithromycin
- Travellers with a history of QT prolongation or certain arrhythmias, or taking other QT-prolonging drugs, need a medication review
- Significant liver disease
- It is not a substitute for care in a child under about 2, a pregnant traveller with severe symptoms, or anyone with a high fever and bloody diarrhea
Alternatives
Rifaximin
Works for non-invasive E. coli diarrhea (common in Mexico and Latin America) but not for Campylobacter, Shigella or Salmonella, so it is a poor choice for Asia and Africa.
Fluoroquinolones (ciprofloxacin, levofloxacin)
Formerly first-line. No longer preferred because of widespread resistance in Asia and FDA warnings about tendon, nerve and other serious side effects.
Bismuth subsalicylate (Pepto-Bismol)
Taken four times a day it can roughly halve the chance of getting travelers' diarrhea, at the cost of a black tongue and stools. Not for children, aspirin-allergic travellers, or people on blood thinners.
How to get it in California
Voyax Health consultations are available to California residents.
Add your destinations on Voyax Health. The health brief rates the food and water risk for each stop and notes when a standby antibiotic is worth carrying.
A licensed pharmacist reviews your health history and current medications, checking for heart-rhythm and interaction concerns, and where appropriate a prescription is issued to your California pharmacy along with guidance on when to take it.
Pack it in your carry-on with oral rehydration salts and loperamide, and keep the instructions with it. Most travellers never open it, which is the best outcome.
Frequently asked questions
Should I take antibiotics to prevent travelers' diarrhea?▼
No. The CDC advises against preventive antibiotics for most travellers because they cause side effects, disturb gut bacteria and encourage resistance. Carry a standby course to treat moderate or severe illness instead, and focus on food and water precautions. Bismuth subsalicylate is the one over-the-counter preventive with reasonable evidence.
Azithromycin or ciprofloxacin for travelers' diarrhea?▼
Azithromycin. Ciprofloxacin resistance is now common in the bacteria that cause travelers' diarrhea, especially Campylobacter in South and Southeast Asia, and fluoroquinolones carry FDA warnings about tendon and nerve damage. Azithromycin works against the full range of common causes with a single dose.
How fast does azithromycin work for travelers' diarrhea?▼
Most people improve within 24 hours, compared with three to five days untreated. If there is no improvement after a day, or you have a high fever or bloody stools, see a doctor rather than taking more.
Can I get azithromycin for travel without seeing a doctor in person?▼
In California, a licensed pharmacist or telehealth clinician can review your trip and health history online and, when appropriate, send the prescription to your pharmacy. Voyax Health includes this in the pharmacist review of your travel plan.
Destinations where this matters
Country guides where this vaccine or medication is commonly part of the plan.
IndiaHigh riskIndia carries a CDC Level 1 travel health notice. Malaria is present throughout India below 2,000m elevation, including major cities. Key travel vaccines: COVID-19, Hepatitis A, Hepatitis B.
MexicoModerate riskMexico carries a CDC Level 1 travel health notice. Malaria risk exists in certain areas of Mexico. Key travel vaccines: COVID-19, Hepatitis A, Hepatitis B.
ThailandModerate riskThailand carries a CDC Level 1 travel health notice. Malaria risk exists primarily in border provinces with Burma, Cambodia, and Malaysia. Key travel vaccines: COVID-19, Hepatitis A, Hepatitis B.
PeruModerate riskPeru carries a CDC Level 1 travel health notice. Malaria risk exists in areas below 2,500m elevation east of the Andes. Key travel vaccines: COVID-19, Hepatitis A, Hepatitis B.
EgyptModerate riskEgypt carries a CDC Level 2 travel health notice. No malaria risk. Key travel vaccines: COVID-19, Hepatitis A, Hepatitis B.
VietnamModerate riskVietnam carries a CDC Level 1 travel health notice. Malaria risk exists in rural areas of Vietnam. Key travel vaccines: COVID-19, Hepatitis A, Hepatitis B.
Get it prescribed for your trip
Enter your destinations and dates. Your free health brief shows whether travelers' diarrhea (standby treatment) is a risk on your route; a licensed pharmacist then reviews your plan for $39.99 per traveller and sends prescriptions to your pharmacy.
Start my free health briefConsultations are available to California residents. Vaccines and medications are paid at your pharmacy.
Sources: CDC Yellow Book — Travelers' Diarrhea. Last updated 2026-09-28. This page is informational and not a substitute for advice from a pharmacist or travel-medicine provider.