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What is a Z-Pak?

Sinus pressure? Check. Headache? Check. Enlarged lymph nodes? Check. Z-Pak? Check.

If you have a bacterial infection, your doctor may prescribe you a Z-Pak. A Z-Pak is an antibiotic commonly prescribed for bacterial infections, like sinus infections, pink eye, or tonsillitis—not viral infections. 

What is a Z-Pak?

A Z-Pak is the brand name for a five-day course of the antibiotic azithromycin that treats bacterial infections by stopping the growth of bacteria in your body. “It’s used for a variety of infections including pneumonia, sinus infections, and ear infections, for example,” explains Amesh Adalja, MD, a board-certified infectious disease physician. 

This prescription drug is manufactured by BOC Sciences, Sun Pharmaceuticals, Sandoz, Alembic, and Pfizer, among other large pharmaceutical companies. Common brands of azithromycin include the Zithromax Z-Pak and the Zithromax TRI-PAK. Azithromycin is also available as an eye drop, called AzaSite. 

Generic azithromycin can cost approximately $37 without insurance, while brand-name Zithromax can cost upwards of $200. However, a SingleCare coupon can reduce that cost to less than $10 for a generic Z-Pak.

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What is a  Z-Pak used for?

A Z-Pak can treat a variety of bacterial infections in adults and children. Some of the most common infections include: 

Of these, strep throat is one of the more common diseases treated by a Z-Pak. Because bacteria cause strep throat, a Z-Pak can prevent bacteria from growing and can decrease the spread of the infection to other people. It can also prevent strep throat from evolving into a more severe illness like rheumatic fever, a condition that can damage your heart valves.

A  Z-Pak cannot treat viral infections, like the flu or the common cold, because viral infections cannot be cured by antibiotics. 

Z-pak dosage

There are two main forms of azithromycin: liquid (in suspension form) and tablets. The dosage strengths for liquid Zithromax are 100 mg/5 mL and 200 mg/5 mL. The most common dosage strengths for the tablets are 250 mg and 500 mg. There are six tablets in a 250 mg Z-Pak. Azithromycin is also available in higher doses as a powder form and used for the treatment of sexually transmitted diseases. 

Although the Z-Pak is the most popular form of azithromycin, sometimes doctors prescribe a Zithromax Tri-Pak, which contains three tablets of azithromycin 500 mg, and is taken once daily for 3 days. The Tri-Pak may be prescribed for mild to moderate acute bacterial exacerbations of chronic bronchitis, or for acute bacterial sinusitis. 

If you have strep throat and are allergic to medications like penicillin or amoxicillin, your doctor may prescribe you a  Z-Pak of six 250 mg tablets. You take two tablets on the first day, followed by one tablet daily on each of the remaining four days.

It’s important to take this medication as directed by your doctor, usually once a day. The dosage will depend on your diagnosis. For the best results, take this antibiotic at approximately the same time every day and continue to take it until you finish the full prescribed amount. Stopping the medication too early may cause bacteria to grow, and your infection to return.

If you miss a Z-Pak dose, take it as soon as you can. If it’s almost time for your next dose, skip the missed dose—it’s not recommended that you take two doses at once.

Z-pak restrictions

While  Z-Paks can help adults and children recover from bacterial infections, there are some precautions to consider before taking the prescription drug. Tell your doctor if you’re:

  • allergic to azithromycin or other antibiotics (this medication may cause allergic reactions in some people)
  • living with liver problems, kidney disease, or myasthenia gravis
  • taking drugs that may cause QT prolongation, you have heart problems, or you have a family history of sudden cardiac arrest
  • planning to get a vaccine soon or have recently had an immunization
  • taking antacids, as these drugs can interfere with azithromycin 
  • pregnant
  • breastfeeding (the drug may pass into your breast milk)

Specifically, talk to your healthcare provider about any interactions with current drugs you’re taking. The following medicines have negative interactions with Z-Paks:

  • Colchicine
  • Amiodarone
  • Disopyramide
  • Dofetilide
  • Dronedarone
  • Ibutilide
  • Pimozide
  • Procainamide
  • Quinidine
  • Sotalol
  • Warfarin

Note: There are no drug interactions between azithromycin and Nyquil, so you can safely take these two drugs together to ease symptoms of a cough, sore throat, headache, fever, runny nose, and sneezing. However, before taking NyQuil or any other cough/cold medication, check with your doctor or pharmacist if the medication is safe to take with your medical conditions or other medications you take. Many cough and cold medications are not safe for people with high blood pressure or glaucoma. 

What are the side effects of Z-Paks?

The most common Z-Pak side effects are:

  • Diarrhea
  • Nausea
  • Abdominal pain
  • Dizziness
  • Fatigue or tiredness
  • Vomiting

Serious side effects of Z-Paks may include: 

  • Hearing loss
  • Blurred vision
  • Difficulty speaking or swallowing
  • Muscle weakness
  • Persistent nausea or vomiting
  • Severe stomach pain

Seek medical help right away if you experience fainting, severe dizziness, a fast or irregular heartbeat, or an allergic reaction. You should also seek medical treatment if any of these side effects persist or worsen.

Azithromycin has also caused abnormal changes in the electrical activity of the heart, which can lead to a potentially fatal irregular heart rhythm, according to the U.S. Food and Drug Administration (FDA). Patients at risk for developing this condition include those who have low blood levels of potassium or magnesium, have a slower-than-average heart rate, or use drugs that treat abnormal heart rhythms (arrhythmia).

Talk to your healthcare provider before taking a Z-Pak to discuss all possible side effects and drug interactions. He or she can provide medical advice on how to avoid or treat adverse effects. For example, taking this medicine with food could prevent an upset stomach.

Are there alternatives to the Z-Pak?

“The medications clarithromycin or  Augmentin are sometimes used as alternatives to the Z-Pak,” according to Chirag Shah, MD, board-certified emergency medicine physician and co-founder of Push Health. “However, these alternatives will not always work to treat the infection for which the Z-Pak was prescribed in the first place, and consultation with one’s medical provider is recommended before changing medications.”

Azithromycin vs. amoxicillin

Amoxicillin is a common alternative to azithromycin. Amoxicillin can be prescribed alone, or as Augmentin, which contains amoxicillin and clavulanate. Clavulanate is added to amoxicillin to prevent resistance. Here’s a side-by-side comparison of how azithromycin and amoxicillin stack up against each other.

Azithromycin Amoxicillin
Brand (generic) Zithromax (azithromycin) Amoxil (amoxicillin)

Augmentin (amoxicillin/clavulanate)

Dosage forms Tablet


Powder packet



Chewable tablet


Common side effects Vomiting, diarrhea, abdominal pain Diarrhea, nausea, skin rash, or hives
Commonly used for Strep throat, pneumonia, middle ear infection, bacterial conjunctivitis, gonorrhea, urethritis, and pelvic inflammatory disease Ear infection, sinusitis, lower respiratory tract infection, urinary tract infection, bite wounds, strep throat

More Z-Pak alternatives

In addition to amoxicillin, there are other alternatives to Z-Paks, such as:

  • Cipro (ciprofloxacin): This affordable antibiotic is effective at treating bacterial infections, but it may have more negative interactions with food and drugs compared to other Z-Pak alternatives. 
  • Vibramycin (doxycycline): This antibiotic treats bacterial infections, like acne, and prevents malaria. However, it may make you more sensitive to sunlight and result in sunburn or a rash.
  • Keflex (cephalexin): Unlike other  Z-Pak alternatives, cephalexin is usually taken multiple times a day, which can be hard to remember for some people. It treats bone infections, UTIs, skin infections, and surgical site infections, among other bacterial infections.
  • Cleocin (clindamycin): This drug is effective in treating acne when used topically, especially when combined with other acne medications. It can also be used orally for serious skin or soft tissue infections. In some cases, clindamycin can cause severe diarrhea, which can be very serious or even fatal. 
  • Levaquin (levofloxacin): This medicine, in the same class as Cipro, treats a variety of bacterial infections.
  • Bactrim (sulfamethoxazole-trimethoprim): This medicine treats bacterial infections, but taking this medicine may make you more susceptible to sunburns.

Related resources for Z-Paks: