Azithromycin (Zithromax®) Antibiotic: Uses, Dosing, and Safety

What Azithromycin Is and How It Works

Azithromycin is a macrolide antibiotic used for many bacterial infections. It blocks bacterial protein synthesis by binding to the 50S ribosomal subunit. It reaches high tissue levels and has a long half-life, so once-daily dosing is common. Azithromycin tablets and azithromycin oral suspension cover typical respiratory pathogens and atypicals such as Mycoplasma, Chlamydophila, and some strains of Streptococcus.

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Common uses include azithromycin for pneumonia, acute bronchitis (bacterial or atypical causes), strep throat in penicillin-allergic patients, sinus infections, and azithromycin for ear infection in children. It may be used for some sexually transmitted infections, such as uncomplicated chlamydia, as directed by a prescriber. Resistance patterns vary by region, and some conditions now prefer other antibiotics. Azithromycin is not a typical choice for urinary tract infections.

Dosage forms include azithromycin 250 mg, azithromycin 500 mg tablets, and azithromycin suspension in pediatric strengths. Pack formats include the azithromycin z pack (azithromycin 250 mg tablets 6 pak) and azithromycin 500 mg 3 tablets for certain 3-day regimens.

Dosage and Usage

• Typical adult z-pack: 500 mg once on day 1, then 250 mg once daily on days 2–5.
• Alternative adult regimen: 500 mg once daily for 3 days (azithromycin 500 mg 3 tablets).
• Strep throat: common regimen mirrors the 5-day course; prescribers may adjust based on local guidance.
• Community-acquired pneumonia: 500 mg daily for 3 days or a 5-day course; sometimes combined with a beta-lactam.
• Uncomplicated chlamydia: single-dose regimens have been used; many guidelines now prefer doxycycline. Follow prescriber directions.
• Mycoplasma genitalium: resistance is common; treatment protocols are evolving. Use only as directed by a clinician.
• Pediatrics (suspension): often 10 mg/kg on day 1, then 5 mg/kg once daily on days 2–5; or 10 mg/kg daily for 3 days. Doses vary by indication.
• Administration: swallow azithromycin tablets whole with water. The suspension should be measured with an oral syringe or dosing spoon.
• With or without food: may be taken with food if stomach upset occurs. Avoid aluminum/magnesium antacids 2 hours before or after dosing.
• Missed dose: take it when remembered the same day. If it is close to the next dose, skip the missed dose. Do not double doses.
• Complete the full course to reduce relapse and resistance risk, even if symptoms improve sooner.

• Store tablets at 15–30°C (59–86°F) in a dry place in the original bottle or blister.
• Store powder for azithromycin suspension at room temperature before mixing. After reconstitution, most products remain stable for 10 days at room temperature. Do not freeze. Shake well before each dose.
• Keep away from heat, moisture, and direct sun. Avoid bathroom storage and hot cars.
• When you travel, keep medicine in carry-on luggage in the labeled container. Bring a copy of your prescription.
• If you use a pill organizer, keep a small desiccant pack and avoid high heat. Do not split one course into multiple containers.
• Keep out of reach of children and pets.

Benefits and Savings

Azithromycin offers convenient once-daily dosing and short treatment courses. It covers many respiratory pathogens and atypicals and is an option for patients who cannot take penicillins or cephalosporins. The long tissue half-life supports 3- to 5-day regimens, and the liquid azithromycin suspension helps with pediatric dosing.

Ordering generic azithromycin tablets can reduce costs. Many patients see 60–80% savings compared with typical US prices. You can compare azithromycin price by pack size and strength, and choose azithromycin 250 mg or azithromycin 500 mg based on your prescription. Larger packs may lower the per-tablet azithromycin cost.

Side Effects and Safety

• Diarrhea or loose stools
• Nausea or vomiting
• Abdominal pain or cramps
• Indigestion, decreased appetite, or gas
• Headache or dizziness
• Fatigue
• Mild rash or itching
• Vaginal yeast infection or oral thrush

Serious effects are uncommon but include severe allergic reactions, liver problems, Clostridioides difficile–associated diarrhea, and heart rhythm changes from QT prolongation (risk increases with certain heart conditions, low potassium or magnesium, or other QT-prolonging drugs). It can worsen myasthenia gravis. Avoid ergot alkaloids. Interactions may occur with warfarin (monitor INR), digoxin, cyclosporine, colchicine, and some statins. Space aluminum/magnesium antacids from azithromycin. In pregnancy or breastfeeding, prescribers weigh risks and benefits by indication.

Azithromycin does not lower blood glucose and is not known to raise hypoglycemia risk with insulin or sulfonylureas.

For more interaction context, see our article on Drug Interactions The Top Interactions That Should Be On Your Radar.

Onset Time

Many people start to feel better within 24–72 hours after the first dose. Fever and sore throat may improve within two days. Cough or sinus pressure can take longer to settle as inflammation resolves. For sexually transmitted infections, prescribers may recommend follow-up testing to confirm cure. Finish the full course even if symptoms improve early.

Compare With Alternatives

Amoxicillin is often first-line for strep throat and many sinus infections when no penicillin allergy exists. It remains effective against typical streptococci but does not cover atypical respiratory pathogens.

Doxycycline Mr is a tetracycline-class option commonly used for atypical pneumonia, COPD exacerbations, and certain tick-borne infections. It can be a first-line choice for uncomplicated chlamydia based on recent guidelines.

Tetracycline is an older tetracycline antibiotic still used for select indications where susceptibility is known. Dietary calcium can affect absorption, so spacing from dairy is important.

Browse conditions such as Bacterial Infections to compare options your prescriber may consider.

Combination Therapy

• Community-acquired pneumonia: azithromycin plus a beta-lactam (for example, amoxicillin/clavulanate or ceftriaxone) when broader coverage is needed.
• Pelvic inflammatory disease: azithromycin may be paired with ceftriaxone and metronidazole per protocols.
• Avoid duplicate macrolides and other QT-prolonging combinations when possible.
• If taken with warfarin, prescribers may monitor INR and adjust dose.
• Separate aluminum/magnesium antacids by at least 2 hours from azithromycin.

Patient Suitability and Cost-Saving Tips

Azithromycin is used for susceptible bacterial infections, not viral colds or flu. It can be considered for patients who cannot take penicillins or cephalosporins, or when atypical coverage is desired. It is available as azithromycin pills and azithromycin suspension to support adult and pediatric dosing.

It may not be suitable in macrolide allergy, prior azithromycin-related liver injury, significant liver disease, or a history of QT prolongation or certain arrhythmias. Low potassium or magnesium increases arrhythmia risk. Use caution with myasthenia gravis. Discuss all medicines, including over-the-counter products and supplements, with a prescriber.

To manage costs, choose generic azithromycin tablets when appropriate, and compare azithromycin 250 mg versus azithromycin 500 mg packs based on your prescription. You can turn on reorder reminders in your account for future needs. While azithromycin for UTI is not typical, your prescriber will choose the most appropriate antibiotic for your infection.

Authoritative Sources

Pfizer labeling for Zithromax (azithromycin)

FDA Prescribing Information for Zithromax (azithromycin)

DailyMed: Azithromycin drug information

Order Azithromycin from YouDrugstore: add to cart, upload your prescription, and we ship with prompt, express shipping.

This page is for educational purposes and is not a substitute for professional medical advice, diagnosis, or treatment.