The 6 Most Common Azithromycin (Z-Pak) Side Effects - GoodRx (2024)

Many of us need antibiotics from time to time. Azithromycin (Zithromax), commonly referred to as a “Z-Pak,” is one antibiotic that you’ve likely heard of. Maybe you’ve even had it in the past. It belongs to a group of medications called macrolide antibiotics, and it’s a helpful option for several bacterial infections. Originally FDA approved back in 1991, it’s also a medication that’s been around for awhile.

It’s also pretty well-tolerated. But like with all medications, it still has some notable side effects to be aware of.

What is azithromycin used for?

Azithromycin is an antibiotic that can be used by kids and adults. It works by stopping the growth of bacteria in your body. Specific uses vary by age, but it treats several types of mild to moderate infections. This includes:

• Middle ear infections

  See Also

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• Certain cases of bronchitis or pneumonia

• Strep throat or tonsillitis

• Bacterial sinus infections

• Skin infections

• Chancroid

• Chlamydia

• Gonorrhea

• COPD flare-ups (exacerbations)

Azithromycin can be given by mouth — as a pill or liquid — or as an infusion into your vein (IV). The pills are swallowed whole and stored at room temperature. You can store the liquid in the refrigerator or at room temperature.

Regardless of the formulation, doses vary widely. The dose depends on what you're treating and how serious your infection is. You should take azithromycin until you finish your prescription, even if you start to feel better after a few days. Don’t stop taking azithromycin unless you experience serious side effects, which we’ll discuss at length below.

6 azithromycin side effects to know about

While azithromycin may be an effective medication, there are a number of side effects you should know about. Below, we'll review six notable side effects to be aware of.

Keep in mind: Side effect percentages reported here are for a standard 5-day course of azithromycin. Side effects, particularly stomach side effects, are more likely to happen when you receive higher doses over a shorter period of time.

1. Diarrhea

Diarrhea is the most common side effect of azithromycin. In clinical trials, up to 5% of people taking azithromycin reported diarrhea as a side effect. But there are ways to help control diarrhea.

For milder cases of diarrhea, diet changes can help. Try to avoid spicy, greasy, or high-fiber foods, such as wheat bread, lentils, and broccoli. There are also over-the-counter (OTC) products, like loperamide (Imodium A-D) or probiotics, that may help. It's also important to stay hydrated if you experience diarrhea.

2. Nausea and vomiting

Nausea is another common azithromycin side effect. In clinical trials, up to 3% of people taking azithromycin experienced nausea. Less than 1% of study participants reported vomiting as a side effect of azithromycin, but it’s still possible.

Diet changes can also help with mild nausea and vomiting symptoms. Eating smaller meals, avoiding food and drinks with strong smells, and avoiding high-fat foods can help manage feelings of nausea and vomiting. There are also many OTC nausea relief medications that you can try if needed.

3. Stomach pain

Mild to moderate stomach pain is another common side effect of azithromycin. This side effect happened to between 2% and 3% of people taking azithromycin in clinical studies.

Severe stomach pain with azithromycin is rare. If it happens, it may be a sign of something more serious, like liver damage or a Clostridium difficile ("C. diff") infection. This type of infection is possible with many antibiotics, including azithromycin. It can cause severe, infectious diarrhea. Depending on how severe the infection is, you may experience watery diarrhea, stomach pain and cramps, and fever.

If you experience stomach pain that is bothersome or doesn’t go away while taking azithromycin, contact your healthcare provider right away.

4. Changes in heart rhythm

Azithromycin can cause irregular heart rhythms in some people.

This is more common in people with low blood levels of potassium or magnesium, people taking medications that control heart rhythm (antiarrhythmics), and older adults. People with certain heart conditions, like long QT syndrome or a history of other heart rhythm problems, are also at additional risk for these changes.

Reports of this azithromycin side effect also prompted the FDA to release a drug safety warning back in 2013. In rare cases, these heart rhythm changes have been fatal. To help prevent and control these risks, make sure your healthcare provider knows your full medical history and all the medications and supplements you take.

5. Liver damage

Changes in liver health are rare, but possible. In clinical trials, liver function tests (blood tests that evaluate your liver health) slightly worsened in a little more than 1% of people. This side effect is usually reversible once you stop the medication.

Still, azithromycin has been known to contribute to liver damage in rare cases. This is a serious side effect that can be life-threatening for some people. The risk is higher if you’ve had liver problems in the past.

Symptoms of liver damage can include nausea or vomiting, yellowing of the skin or eyes (jaundice), or intense stomach pain. Be sure to let your healthcare provider know if you have a history of liver problems before starting azithromycin.

6. Serious skin reactions

Very rarely, azithromycin can cause serious skin reactions, including Stevens-Johnson syndrome, toxic epidermal necrolysis, and drug reaction with eosinophilia and systemic symptoms (DRESS) syndrome. If you develop painful skin blisters or a significant rash while taking azithromycin, you should stop the medication and seek medical attention immediately. These conditions are medical emergencies.

As a precaution, if you develop any new skin rashes while taking azithromycin, it’s recommended to contact your healthcare provider as soon as you can to make sure it's not a sign of something more serious. If it's not deemed serious, they may recommend applying a cool compress, such as a wet washcloth or ice pack, to the affected area. You could also consider trying OTC products, like hydrocortisone cream, to help relieve the redness or itching.

When should I contact my healthcare provider about side effects from azithromycin?

This depends on the type of side effects you're having. You should immediately contact your healthcare provider for any serious and/or worrisome side effects that are affecting you.

Examples of when to contact your healthcare provider can include:

• Skin rash

• Yellow eyes or skin

• Intense nausea or vomiting

• Dark-colored urine

• Fast or irregular heartbeat

• Severe diarrhea or bloody stool

• Severe stomach pain

If you're worried about any side effects you're experiencing, or if your current side effects get worse at any point, contact your healthcare provider right away.

Also, make sure to listen to your body. If you’re experiencing symptoms that feel severe or life-threatening, it’s better to seek medical attention right away. Similarly, severe allergic reactions to azithromycin are rare, but possible. Call 911 immediately or go to the nearest emergency room if you have trouble breathing or experience swelling of the face, lips, or tongue.