7 Erythromycin Side Effects and How to Manage Them

Erythromycin (Ery-Tab, E.E.S., EryPed) is a relatively common antibiotic that treats bacterial infections. It’s effective when you need it, but it may cause side effects too. Thankfully, these side effects are typically mild and go away on their own. However, some side effects are more serious and need prompt medical attention.

Here's what you should know about erythromycin side effects. We’ll go over mild effects to expect and when to reach out to a healthcare professional if your symptoms become more serious. Here, we’ll focus on the oral form of erythromycin.

Erythromycin side effects at a glance

Erythromycin is well tolerated overall. Its main side effects relate to your stomach, or digestive tract. They often get better as your body gets used to the medication (or after you finish it).

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Common erythromycin side effects include:

• Nausea

• Vomiting

• Diarrhea

• Stomach pain 

• Loss of appetite

• Mild skin rashes

Rare but serious side effects that may warrant medical attention include:

• Liver problems

• Irregular heart rhythm

• Severe skin reactions

• Severe diarrhea 

We’ll explore seven of these erythromycin side effects in more detail.

1. Nausea

Nausea, or queasiness, is the most common erythromycin side effect overall.

The medication works best when taken on an empty stomach, about 30 minutes before or 2 hours after meals. However, taking it without food may give you a stomach ache. Here are some tips to help with nausea if it happens:

• Avoid lying down for at least 30 minutes after taking the medication.

• Take small sips of clear fluids and avoid strong-smelling food to help ease queasiness. 

• Though it’s not ideal, you can try taking your medication with a light meal if nausea persists. A small, bland snack, such as toast or crackers, may also help.

• Consider trying ginger or peppermint products.

• Ask your prescriber about trying an over-the-counter nausea medicine.

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If you can’t eat or drink at all, or if nausea prevents you from taking your medication, contact your healthcare professional for further guidance. 

2. Diarrhea

Diarrhea is another common side effect of erythromycin. It usually stops once you finish taking the medication.

For milder diarrhea symptoms, a few simple measures can go a long way:

• Drink plenty of water and clear fluids to stay hydrated.

• Stick to bland, easy-to-digest foods, such as oatmeal or yogurt.

• Avoid caffeine and high-fat dairy products (i.e., butter or cheese) until your symptoms improve.

In rare cases, diarrhea can cause bigger problems. Erythromycin increases the chance of developing a Clostridioides difficile (C. diff) infection. C. diff is a bacteria that normally lives in your gut, but antibiotics like erythromycin can disrupt the balance of gut bacteria. This can make too much C. diff to grow in your stomach and release toxins. These toxins can cause diarrhea and make people very sick. They can also lead to symptoms such as fever and severe stomach pain. 

If you notice these symptoms, stop taking erythromycin and call your healthcare professional right away. If your symptoms are severe, you’ll likely need treatment in a hospital.

3. Stomach pain

Stomach pain is another possible side effect of erythromycin. It usually feels like gnawing or cramping in your upper abdomen. This happens because erythromycin can trigger stomach contractions.

Here’s how to ease stomach pain while taking erythromycin:

• Eat smaller, more frequent meals instead of fewer, large ones.

• Stay upright for at least 30 minutes after taking your dose.

• Take your dose with food or low-fat milk to reduce irritation.

• Avoid spicy or fatty foods, which can make pain worse.

• Stick to bland foods like crackers if your stomach feels upset.

Most importantly, listen to your body. If you’re experiencing intense stomach pain alongside a fever, call your healthcare professional immediately. You should also contact them if your pain gets worse at any point.

4. Loss of appetite

You might not want to eat much while taking erythromycin. Even so, do your best to maintain close to your typical nutritional intake. Food provides the nutrients and energy your body needs to strengthen the immune system. That should help it fight off infections more effectively alongside the antibiotic.

Appetite loss isn’t usually serious with erythromycin. It likely won’t last long. But if you find yourself skipping meals, eating much less, or losing weight, talk to your healthcare professional. Also contact them if you develop symptoms such as severe abdominal pain or jaundice (yellowing of your skin or eyes). This could be a sign of liver problems, a rare side effect of erythromycin.

5. Liver problems

Erythromycin can occasionally affect the liver. About 1% to 2% of people taking erythromycin experience mild liver enzyme changes, but these should go away on their own.

In rare cases, erythromycin can cause more serious liver issues, such as jaundice or changes in liver function. If you have a history of liver problems, you may have a higher risk of developing more serious problems. 

Liver problems may come without any noticeable symptoms. But possible warning signs to watch for include:

• Unexplained stomach pain, especially in the upper right side

• Appetite loss

• Unexplained nausea or vomiting

• Dark urine or pale-colored stools

• Jaundice

These are all telltale signs of a potential liver problem. If you notice any of them, contact your healthcare professional right away. They may want to analyze your blood work to see if any next steps are necessary.

6. Abnormal heart rhythm

Erythromycin can sometimes affect your heart rhythm, making it beat irregularly. In rare cases, this can be dangerous, and lead to a heart condition called QT prolongation. The risk of QT prolongation is higher if you’re older than 65, have preexisting heart disease, or take other medications that affect the heart. 

Before taking erythromycin, let your healthcare professional know if you have heart conditions. Make sure to give them a full list of the medications and supplements you take. This will help them check for erythromycin interactions.

If you experience sudden dizziness, fainting, heart palpitations, or chest pain, call 911 or go to the nearest ER immediately.

7. Skin reactions

Erythromycin can sometimes cause skin reactions. These can range from mild to severe.

Even if you only notice a mild rash, hives, or itching, it’s important to let your healthcare professional know. In rare cases, these reactions can develop into serious allergic conditions such as Stevens-Johnson syndrome or toxic epidermal necrolysis, which can cause painful blisters, peeling skin, and skin detachment. Symptoms usually appear within the first 2 days of starting erythromycin.

If you develop blistering or peeling skin, stop taking erythromycin right away. Call 911 or go to the nearest ER if you experience trouble breathing, swelling in your face or throat, or chest tightness.

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Written by:

Goldina Erowele, PharmD, MBA

Dr. Goldina Ikezuagu Erowele is a transformative leader in healthcare with a distinguished record of advancing medication safety, operational efficiency, and cost management.

Edited by:

Joshua Murdock, PharmD, BCBBS

Joshua Murdock, PharmD, BCBBS, is a licensed pharmacist in Arizona, Colorado, and Rhode Island. He has worked in the pharmacy industry for more than 10 years and currently serves as a pharmacy editor for GoodRx.

Reviewed by:

Alex Brewer, PharmD, MBA

Alex Brewer, PharmD, MBA, is a licensed pharmacist specializing in chronic disease and health and wellness. Upon completing his residency, he worked in the managed care field, conducting medication therapy management and adherence counseling sessions with Medicaid, Medicare, and private insurance patients, before transitioning to a career in medical writing.

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