Rx required in the US, UK, and Canada

Azithromycin

Also called Zithromax, Z-Pak, Zmax. Macrolide antibiotic.

Selected susceptible infections. A Z-Pak is a packaging schedule, not the usual treatment for sinusitis or bronchitis.

Last reviewed 2 November 2026. RxNorm 18631. SNOMED CT substance 387531004.

What azithromycin treats

Primary uses clinicians actually reach for this drug for. Local resistance and your own history can take a use off the list.

Some community respiratory infections caused by susceptible organisms, including certain pneumonias, when a clinician chooses a macrolide.
Some sexually transmitted infections, on a regimen the clinician selects. Partners often need treatment too.
A few other labeled uses, including some traveler’s diarrhea and some skin infections, when the bacteria are likely to respond.

Asking for a Z-Pak because it is familiar is not an off-label indication. Macrolide resistance is common in some respiratory bacteria, so a past prescription is not a reason to repeat it.

What it does not treat

Colds, flu, and COVID-19
Most acute bronchitis
Routine sinusitis, where a penicillin-class drug is the usual first-line choice if an antibiotic is used at all
Strep throat as a casual substitute for penicillin
A dental abscess instead of a dentist

Forms, dosing examples, and how to take it

Forms

Tablets, including the 6-tablet Z-Pak and the 3-tablet Tri-Pak
Oral suspension
Zmax is an extended-release product with its own one-time schedule. Do not split it into a Z-Pak plan.

Adult examples

The branded packs are product designs. They are not a sinus dose and not a bronchitis dose. Searchers looking for an azithromycin dosage for a sinus infection usually need a different plan, or no antibiotic.

Educational examples only. Not a dosing instruction for a named patient.
Situation	Example adults may see on a label or guideline	Limit
Z-Pak, the familiar 5-day pack	500 mg on day 1, then 250 mg once daily on days 2 through 5	This is what is in that pack. It is not evidence that a sinus infection or a chest cold should be treated with it.
Some adult indications on labeling	500 mg once daily for 3 days	A Tri-Pak follows this pattern. The prescriber chooses the pack, not the patient.
Sinusitis or acute bronchitis	No routine azithromycin dose	When bacterial sinusitis is treated, amoxicillin or amoxicillin-clavulanate is the usual first-line drug. Most bronchitis is viral.

Food, minerals, and administration

Tablets can usually be taken with or without food. Follow the product you were given.
Separate aluminum or magnesium antacids from the dose if the label says so, often by a couple of hours.
Tell the clinician about a long QT interval, fainting, low potassium or magnesium, heart failure, and other QT-prolonging drugs, including some antiarrhythmics, some antipsychotics, and methadone.

Can an online doctor prescribe azithromycin?

Yes only inside the narrow band below. The same visit is supposed to refuse the drug outside that band.

When a prescription is plausible

Yes, when the indication is one a remote clinician can justify and the heart-rhythm history is acceptable.
A legitimate visit will often refuse a Z-Pak for a three-day sinus illness or a chest cold, and that refusal is the correct clinical result.

What the visit should cover

How many days you have been ill, and whether you improved and then worsened.
Heart-rhythm history and the rest of your medication list.
Penicillin allergy details, if you are asking for a macrolide only because of that label.
Pregnancy, liver disease, and whether an STI or pneumonia is actually the question.

When the clinician should refuse

Symptoms under 10 days that fit a cold or viral sinusitis.
Uncomplicated bronchitis.
A known long QT, recent fainting, or a dangerous combination of QT drugs, unless a clinician who can monitor decides the benefit is extraordinary.
A request to use a leftover Z-Pak while a tooth swells or breathing worsens.

How same-day e-prescriptions and local pickup work. If the drug is prescribed, use a pharmacy you can reach today. Mail order is the wrong speed for an acute infection.

Side effects, allergies, pregnancy, and alcohol

Often mild

Nausea
Diarrhea
Abdominal pain
Headache

Get care

Fainting, pounding heart, or a seizure
Yellow skin or dark urine
Severe watery diarrhea
Swelling of the mouth or trouble breathing

Allergies and cross-reaction

A macrolide allergy is its own history. Azithromycin is not the automatic substitute for a penicillin allergy, and it is not safe merely because it is not a penicillin. Tell the clinician about any prior azithromycin or erythromycin reaction.

Pregnancy

Azithromycin is used in pregnancy for some infections when the benefit is clear. The obstetric clinician decides. Do not start a partner’s leftover pack.

Alcohol

There is no disulfiram-style warning. Alcohol does not remove the heart-rhythm risk, and it can worsen dizziness and dehydration.

Severe watery diarrhea during or after any antibiotic can be C. difficile. Mouth or throat swelling is an emergency: call 911 or 999.

Generic, coupon, and telehealth pickup

These are budgeting bands for a common U.S. generic fill, not a national average and not a GoodRx quote. Discount-card prices change by pharmacy and ZIP code, and a card usually cannot be combined with insurance on the same fill. A telehealth visit is a separate bill, often advertised around $29 to $129 in late October 2026. The medicine is extra. Ask the pharmacy for today’s cash price and today’s coupon price before you travel.

Average-style planning bands for budgeting. Confirm the live cash price and the live coupon.
Product	U.S. cash planning band	Discount-card band, GoodRx-type	Telehealth plus local pickup
Generic azithromycin equivalent to a 6-tablet Z-Pak	Often about $15–$45	Often about $8–$25	Visit fee plus local pickup. Do not mail-order a pack for a worsening infection.
Brand Zithromax or Zmax	Usually higher than generic	Rarely the better buy	Zmax is a different release. Do not substitute it for tablets.

Questions about azithromycin

What is the azithromycin dosage for a sinus infection?

For most people there isn’t one. Sinus symptoms under 10 days are usually viral. When a bacterial sinus infection is treated, a penicillin-class drug is the usual first-line choice, not a Z-Pak. A clinician who knows your allergies and local resistance can still choose something else. Do not start the pack in the drawer.

Can an online doctor prescribe a Z-Pak?

An online doctor can prescribe azithromycin when it fits and the law allows. Many will refuse it for bronchitis and routine sinusitis. The refusal is not a cue to buy it without a prescription.

How is a Z-Pak taken if it is prescribed?

The standard pack is 500 mg on day 1 and 250 mg once daily on days 2 through 5. Take the tablets you were dispensed, on that label. A Tri-Pak and Zmax are different products.

What should I do if I miss a dose?

Take a missed dose when you remember unless it is close to the next dose. Skip it then. Do not take two doses at once. If you vomit soon after a dose, ask the pharmacist before you repeat it. The label and the pharmacist outrank this sentence.

Can I drink alcohol on azithromycin?

There is no Flagyl-type reaction. Skip alcohol if you feel faint, have a racing heart, or are dehydrated. Get emergency care for fainting or severe chest symptoms.

Labels: DailyMed. Stewardship: CDC. Pharmacy checks: FDA BeSafeRx. Codes were read from RxNav on 2 November 2026 for ingredient RxCUI 18631.