Key takeaways:
Azithromycin (Zithromax) is a macrolide antibiotic that treats bacterial infections. It’s a commonly prescribed medication for both adults and children.
Common azithromycin side effects include diarrhea, nausea, and stomach pain. Rare but serious side effects include severe skin reactions, liver damage, and heart rhythm problems.
Most azithromycin side effects are relatively mild and can be managed at home. But if you develop symptoms that feel bothersome or severe, you should contact your prescriber right away.
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Getting sick happens. And sometimes, you need an antibiotic to start feeling better.
Azithromycin (Zithromax), commonly referred to as a Z-Pak, is a macrolide antibiotic that’s been around for a while. You’ve likely heard of it before, or maybe you’ve even taken it in the past.
Azithromycin, which treats several different bacterial infections, is generally well tolerated. But, like with all medications, there are some notable azithromycin side effects to be aware of.
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Azithromycin side effects at a glance
Most people don’t experience many side effects with azithromycin. When it does cause side effects, though, they’re usually mild and can be managed at home.
Common or mild azithromycin side effects
The following side effects tend to be more common or mild:
Diarrhea
Nausea or vomiting
Stomach pain
Gassiness
Fatigue
Headaches
Dizziness
Itchy skin
Loss of appetite
Taste changes
Rare but serious azithromycin side effects
The following side effects are less common, but potentially serious:
Liver damage
Severe skin reactions
Heart rhythm problems
Infectious diarrhea
Knowing about the possible side effects of azithromycin can help you manage them better if they happen. Here, we’ll take a closer look at 10 azithromycin side effects you should know about.
1. Diarrhea
Diarrhea is the most common side effect of azithromycin. In clinical trials, up to 5% of people taking azithromycin reported experiencing diarrhea.
If you have diarrhea related to azithromycin, there are strategies to manage it. Temporary diet changes can help in milder cases. Try to avoid spicy, greasy, or gas-producing foods, such as wheat bread, lentils, and broccoli. Be sure to stay hydrated by drinking clear liquids if you experience diarrhea. This helps replace fluids lost from diarrhea.
In rare cases, azithromycin can lead to a Clostridioides difficile (C. diff) infection. This happens when antibiotics disrupt the balance of bacteria in your gut, allowing C. diff to grow and produce toxins. Symptoms can include frequent watery or bloody diarrhea, stomach cramps, and fever. These symptoms may develop during treatment or within a few months after your last dose.
Contact your healthcare team right away if you develop symptoms of C. diff. Don’t take an antidiarrheal medication unless they tell you it’s safe to do so.
2. Nausea and vomiting
Nausea is another relatively common azithromycin side effect. Vomiting is less likely, but it’s also possible.
If you have an upset stomach while taking azithromycin, consider taking your upcoming doses with food. This can help ease nausea.
Temporary diet changes can help with mild nausea and vomiting, too. Eating smaller meals and avoiding strong-smelling or high-fat items can lessen nausea, for example. OTC anti-nausea medications are also available, if needed.
3. Stomach pain
Mild-to-moderate stomach pain is another possible side effect of azithromycin.
Stomach pain related to azithromycin usually goes away on its own. Though, while rare, severe stomach pain is possible and could be a sign of something more serious, such as liver damage or a C. diff infection.
If you experience stomach pain that’s bothersome or doesn’t go away, contact your prescriber right away.
4. Loss of appetite
You might notice that you’re not as hungry while taking azithromycin. This has been reported by a number of people taking the antibiotic.
If you find yourself eating less or not feeling hungry, it’s important to try to maintain a balanced diet to support your immune system while you recover.
It may be helpful to eat smaller, more frequent meals. Focus on foods that are easy to digest, such as soups, smoothies, and soft fruits. And try to avoid foods high in sugar, such as candy and soda.
If your appetite doesn’t return after you stop taking azithromycin, be sure to let your prescriber know. They can help figure out the cause and determine next steps.
5. Headaches
Headaches are possible with azithromycin. They’re usually mild and can be managed with OTC headache medications, such as acetaminophen (Tylenol) or ibuprofen (Advil, Motrin). Staying hydrated and getting quality sleep, when possible, can also ease headache pain.
Good to know: Some people take decongestants, such as pseudoephedrine (Sudafed), when they’re feeling sick. But pseudoephedrine can cause headaches as a side effect. Try to avoid decongestants and other medications that cause headaches while taking azithromycin.
6. Feeling tired or dizzy
It’s common to feel more tired than usual when you’re sick. But some people also report feeling especially fatigued while taking azithromycin. This tiredness may be accompanied by dizziness, which can leave you feeling lightheaded and unsteady.
Getting enough rest, staying hydrated, and eating regularly may help. If you feel dizzy, sit or lie down until it passes. When you’re ready to get up again, stand up slowly. Wait until you’re feeling better to drive or perform activities that require alertness.
Contact your healthcare team if these symptoms are severe, persistent, or getting worse. Seek medical care right away if the dizziness comes with fainting, chest pain, or a fast or irregular heartbeat.
7. Changes to your sense of taste
In rare cases, people report changes in their sense of taste after starting azithromycin. This includes having bitter or sour taste in the mouth, which can make certain foods taste weird or different than normal. Loss of taste is also possible.
Taste changes related to azithromycin are usually temporary and resolve once the medication is stopped. In the meantime, chewing sugar-free gum or eating flavorful foods can help mask unusual tastes.
8. Changes in heart rhythm
Azithromycin can cause irregular heart rhythms in some people. That’s because it can prolong the QT interval — the time it takes the heart to recharge itself between each beat. This is more likely to happen in people who:
Are older
Take heart rhythm medications (antiarrhythmics)
Take other medications that prolong the QT interval
Have low blood levels of potassium or magnesium
Have certain heart conditions, such as long QT syndrome
Reports of this side effect prompted the FDA to release a drug safety warning in 2013. In rare cases, these heart rhythm changes have been fatal. So be sure your prescriber knows your full medical history and has a list of all the medications and supplements you take, so they can help you manage this risk.
9. Liver damage
Changes in liver health related to azithromycin are uncommon, but possible. In clinical trials, liver function tests (blood tests that evaluate liver health) slightly worsened in a small number of people taking azithromycin.
This side effect is usually reversible once the medication is stopped. But, in rare cases, azithromycin has been known to contribute to actual liver damage. This is a serious side effect that can be life-threatening for some people. The risk of liver damage related to azithromycin is higher for people who have had liver problems in the past.
Symptoms of liver damage can include nausea or vomiting, yellowing of the skin or eyes (jaundice), and intense stomach pain. Be sure to let your prescriber know if you have a history of liver problems before starting azithromycin.
10. Serious skin reactions
In rare cases, azithromycin can cause serious skin reactions, including Stevens-Johnson syndrome, toxic epidermal necrolysis, and drug reaction with eosinophilia and systemic symptoms (DRESS) syndrome. These skin conditions can be dangerous if left untreated.
As a precaution, if you develop a new rash while taking azithromycin, contact your prescriber as soon as you can. This should be done to make sure the rash isn’t a sign of something more serious.
If the rash isn’t serious, your prescriber may just recommend applying a cool compress, such as a wet washcloth or ice pack, to the affected area. They may also recommend trying an OTC product, such as hydrocortisone cream, to help relieve redness or itching.
If you develop painful skin blisters or a significant rash while taking azithromycin, your prescriber will likely want you to seek emergency medical care.
How long do azithromycin side effects last?
Mild azithromycin side effects — such as appetite changes, fatigue, and headaches — typically get better within a few days of starting azithromycin. And most side effects resolve after the medication is stopped.
There are some exceptions to this, though. More serious side effects like liver damage and severe skin reactions usually require medical attention and take more time to go away.
Remember: Keep taking azithromycin until you run out of your prescribed doses, even if you’re feeling better. Completing your full course of antibiotics will help your body get rid of any residual bacteria that could make you sick again.
When to contact a healthcare professional
As mentioned above, most azithromycin side effects are mild and improve after you finish taking the medication. But you should contact your healthcare team if any side effects are severe or are getting worse. You should also let them know if your infection symptoms don’t start to improve within a few days or start to worsen.
Seek medical care right away if you develop:
A fast or irregular heartbeat, chest pain, or fainting
Severe, watery, or bloody diarrhea
Yellow skin or eyes, dark urine, or severe abdominal pain
A widespread, blistering, or peeling rash
Facial or throat swelling, trouble breathing, or other signs of a severe allergic reaction
If any symptoms feel life-threatening, call 911 or go to the nearest ER.
Frequently asked questions
You can generally take Azithromycin during pregnancy. Most studies haven’t found that it raises the risk of miscarriage or birth defects. It’s also not expected to raise the risk of problems such as preterm delivery or low birth weight.
A few studies have raised concerns about certain birth defects, but the overall evidence hasn’t shown an increased risk. Make sure your prescriber knows you’re pregnant so they can weigh the benefits and risks of treatment.
Taking azithromycin with a small meal may help reduce nausea, diarrhea, and stomach pain. Most tablets and standard liquid formulations can be taken with food.
It may also help to stay hydrated and choose bland foods if your stomach is upset. Don’t take an antidiarrheal medication without checking with your healthcare team. Contact them if your side effects are severe or don’t improve.
You can generally take Azithromycin during pregnancy. Most studies haven’t found that it raises the risk of miscarriage or birth defects. It’s also not expected to raise the risk of problems such as preterm delivery or low birth weight.
A few studies have raised concerns about certain birth defects, but the overall evidence hasn’t shown an increased risk. Make sure your prescriber knows you’re pregnant so they can weigh the benefits and risks of treatment.
Taking azithromycin with a small meal may help reduce nausea, diarrhea, and stomach pain. Most tablets and standard liquid formulations can be taken with food.
It may also help to stay hydrated and choose bland foods if your stomach is upset. Don’t take an antidiarrheal medication without checking with your healthcare team. Contact them if your side effects are severe or don’t improve.
The bottom line
Azithromycin (Zithromax) is a macrolide antibiotic used to treat bacterial infections. Common azithromycin side effects include stomach upset, diarrhea, and headaches. In rare cases, serious side effects, such as liver damage and severe skin reactions, are also possible.
You’ll likely be able to manage mild azithromycin side effects at home with temporary diet changes and over-the-counter (OTC) medications. But if you have side effects that are bothersome or severe, let your prescriber know right away. They'll let you know if it’s OK to keep taking azithromycin or if it’s better to stop.
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References
Alembic Pharmaceuticals. (2025). Azithromycin tablet, film coated [package insert]. DailyMed.
LiverTox: Clinical and Research Information on Drug-Induced Liver Injury. (2025). Azithromycin. National Institute of Diabetes and Digestive and Kidney Diseases.
McMullan, B. J., et al. (2015). Prescribing azithromycin. Australian Prescriber.
MotherToBaby. (2026). Azithromycin (Z-Pak).
National Heart, Lung, and Blood Institute. (2022). Long QT syndrome.
U.S. Food and Drug Administration. (2013). FDA drug safety communication: Azithromycin (Zithromax or Zmax) and the risk of potentially fatal heart rhythms.
