7 Amoxicillin Side Effects You Should Know About
Key takeaways:
Amoxicillin (Amoxil) is a prescription medication that treats several types of bacterial infections, such as strep throat, ear infections, and more. It’s a type of penicillin antibiotic.
The most common amoxicillin side effects are nausea, vomiting, and diarrhea. These usually go away after you finish taking the medication.
Contact your healthcare professional (HCP) right away if you experience any serious side effects, such as severe diarrhea or symptoms of an allergic reaction.
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Over the years, amoxicillin (Amoxil) has been recommended as a first-choice antibiotic for several illnesses, such as strep throat and ear infections. It’s widely available across the U.S., and it’s pretty affordable, too.
Amoxicillin is also well-tolerated overall. But, like with all medications, it has a number of side effects, varying from mild and manageable to those that are a bit more serious. If you or your child have been prescribed amoxicillin for a bacterial infection, it’s best to be aware of the possible risks.
Amoxicillin side effects at a glance
Most of amoxicillin’s side effects are manageable, temporary, and go away after you finish the antibiotic. But some can become severe and require assistance from a healthcare professional (HCP).
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Common amoxicillin side effects include:
Nausea
Vomiting
Diarrhea
Skin rash
Headache
Rare but potentially serious amoxicillin side effects include:
Taste and smell changes
Severe allergic reactions
Liver problems
Anemia (low red blood cells)
Dizziness
To help prevent and control these risks, it’s recommended to talk with your HCP about amoxicillin side effects before you start taking it. To get the conversation started, here are seven amoxicillin side effects to keep in mind.
How to take it: The amount of amoxicillin you’ll need to take will vary based on your age and other factors. Learn more about amoxicillin dosages for kids and adults here.
A fast action plan: Amoxicillin starts working pretty quickly. But its effects aren’t immediate. Here’s what to know about how long amoxicillin takes to work.
Augmentin 101: Augmentin is a similar antibiotic that also contains amoxicillin. Hear from three people about what to expect while taking Augmentin.
1. Nausea
Nausea is one of the most common amoxicillin side effects. But it’s usually mild when it happens. Taking it with food can help lessen or prevent this unpleasant side effect. There are also over-the-counter (OTC) medications available to help manage nausea, such as Dramamine (dimenhydrinate) and Bonine (meclizine).
2. Vomiting
Nausea and vomiting tend to go hand-in-hand. Vomiting is also one of the more common amoxicillin side effects.
Taking amoxicillin with food can help prevent and control vomiting. You may also consider trying an electrolyte drink — such as Pedialyte or Gatorade — if you experience vomiting. This can help replenish electrolytes that your body may have lost.
If you or a loved one vomits soon after taking amoxicillin, contact your HCP about what to do next. Whether you need to take another dose depends on certain factors, such as how soon you threw up after taking your last amoxicillin dose.
3. Diarrhea
Diarrhea is another common side effect of antibiotics such as amoxicillin. Augmentin has been reported to cause diarrhea more often than amoxicillin alone, but it’s still possible with amoxicillin. Augmentin contains amoxicillin and the antibiotic clavulanate — the combination helps boost the medication’s ability to fight certain infections. Clavulanate is also thought to speed up muscle movement in your stomach, which can cause diarrhea.
Diarrhea from amoxicillin is usually mild. But taking amoxicillin with food can help prevent it from happening in the first place. You can also try using the BRAT diet to manage mild diarrhea. This is an acronym that stands for bananas, rice, applesauce, and toast, which are foods that are gentle on your stomach. Electrolyte drinks and water are also helpful for hydration.
When needed, OTC medications for diarrhea can also act as a source of relief. Imodium A-D (loperamide) is one popular option to consider.
In rare cases, diarrhea can become severe. Antibiotics such as amoxicillin can contribute to severe, infectious diarrhea that requires immediate medical attention. This is known as Clostridioides difficile (“C. diff”) diarrhea. Symptoms of this include:
Severe diarrhea
Nausea
Stomach pain or tenderness
Loss of appetite
Fever
4. Skin rashes
Rashes are another relatively common side effect of amoxicillin. Thankfully, these rashes aren’t usually serious. They tend to go away after a few days. A typical amoxicillin rash looks like flat, red patches on the skin. Benadryl (diphenhydramine) and hydrocortisone cream are OTC medications that can help manage skin rashes.
However, if you experience hives — raised, itchy bumps — this could be the sign of an allergic reaction (allergic skin rash). We’ll discuss allergic reactions below.
5. Headache
It can be frustrating to experience headaches. Many medications — including amoxicillin — have the potential to cause headaches to some degree.
Thankfully, with amoxicillin, headaches are typically minor and go away after finishing your treatment. When needed, OTC medications such as Tylenol (acetaminophen) can help manage headaches.
6. Taste and smell changes
Some people experienced a metallic or sour taste in their mouth while taking amoxicillin in clinical studies. Similar taste and smell changes have also been reported to the FDA in some instances.
This side effect may seem alarming, but it isn’t typically permanent.
7. Allergic reactions
Allergic reactions are a common concern with amoxicillin. About 10% of people report having an allergic reaction to penicillin antibiotics, which includes amoxicillin. But only about 1% actually have a true allergy.
Skin rashes involving hives are one common sign of a true allergy. Other possible symptoms of a penicillin allergy include wheezing, throat tightness, or a fast heartbeat.
Also keep an eye out for signs and symptoms of severe allergic reactions, called anaphylaxis. Symptoms may include trouble breathing or swelling of the face, tongue, or throat. Anaphylaxis is a medical emergency, so seek emergency treatment right away if you or a loved one are experiencing anaphylaxis.
What should you avoid while taking amoxicillin?
It’s best to avoid alcohol while taking amoxicillin. While there isn’t a direct interaction between the two, they both cause similar side effects, such as nausea, vomiting, and diarrhea. Alcohol can also weaken your immune system. This makes it harder for your body to fight the infection that amoxicillin is treating.
Amoxicillin may also interact with certain medications you’re taking. This may change how amoxicillin or your other medications work. For example, taking blood thinners, such as warfarin (Coumadin, Jantoven), with amoxicillin could raise your risk of bleeding. The gout medication allopurinol (Zyloprim) raises your chances of experiencing a rash when paired with amoxicillin. Another gout medication, probenecid, can also increase the risk of amoxicillin side effects.
You won’t typically need to stop any of your medications unless you experience serious side effects. But your HCP will likely monitor you closely if you’re taking medications that interact with amoxicillin. It’s also a good idea to give a current medication list handy to your pharmacist. They can check to see if any of your medications interact with amoxicillin.
Can you take amoxicillin on an empty stomach?
Yes, you can take amoxicillin on an empty stomach. But taking it with food may help prevent an upset stomach. Food won’t affect how amoxicillin works in your body, either.
What’s more, you should always take Augmentin with food. It’s harder on the stomach than amoxicillin alone.
The bottom line
Amoxicillin (Amoxil) is typically well-tolerated, but nausea, vomiting, and diarrhea are some of its most common side effects. In rare cases, more serious amoxicillin side effects are also possible. Make sure to reach out to your prescriber right away if you experience any severe symptoms — like trouble breathing or diarrhea that doesn’t stop.
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References
Akhavan, B. J., et al. (2023). Amoxicillin. StatPearls.
Centers for Disease Control and Prevention. (2017). Evaluation and diagnosis of penicillin allergy for healthcare professionals: Is it really a penicillin allergy?
Kan, Y., et al. (2021). Evaluation of antibiotic-induced taste and smell disorders using the FDA adverse event reporting system database. Scientific Reports.
Kuehn, J., et al. (2015). Reported rates of diarrhea following oral penicillin therapy in pediatric clinical trials. The Journal of Pediatric Pharmacology and Therapeutics.
MedlinePlus. (2023). C. diff infections.
Palms, D. L., et al. (2019). First-line antibiotic selection in outpatient settings. Antimicrobial Agents and Chemotherapy.
PD-Rx Pharmaceuticals, Inc. (2024). Amoxicillin capsules [package insert].
Thambavita, D. D., et al. (2021). Pharmacokinetics and bioequivalence of two amoxicillin 500 mg products: Effect of food on absorption and supporting scientific justification for biowaiver. Journal of Pharmaceutical Sciences.
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