Key takeaways:
Augmentin (amoxicillin / clavulanate) is a widely-used antibiotic that treats bacterial infections. It’s generally safe and effective, but it can come with some side effects.
Diarrhea, nausea and vomiting, and skin rashes are common Augmentin side effects. They’re generally mild and go away after the antibiotic is finished.
Rare but possibly serious Augmentin side effects are also possible. Liver problems and blistering skin rashes warrant medical attention.
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If you have a bacterial infection, Augmentin (amoxicillin / clavulanate) is a common antibiotic your prescriber may turn to. It treats various infections, ranging from ear and sinus infections to urinary tract infections. It’s in the same family of antibiotics as penicillin (Penicillin VK).
Augmentin is a combination of two medications — amoxicillin and clavulanate — and each one plays a specific role. Amoxicillin is the antibiotic that fights unwanted bacteria. Clavulanate is the sidekick. It strengthens amoxicillin by stopping bacteria from breaking it down.
For most people, Augmentin is effective and safe. But it’s not without its side effects.
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Augmentin side effects at a glance
Common and/or mild side effects of Augmentin include:
Diarrhea
Nausea
Skin rashes and itchiness
Upper respiratory infections, such as the common cold
Yeast infections
Rare but serious risks include:
Infectious diarrhea
Liver problems
Drug-induced enterocolitis syndrome, a rare type of gut inflammation
Serious skin reactions, including Stevens-Johnson syndrome
Anaphylaxis
Coming up is a closer look at six of the most notable Augmentin side effects and how to deal with them.
1. Diarrhea
Diarrhea is the most common side effect of Augmentin. Nearly 1 in 10 people who take it develop diarrhea. Diarrhea is more common with Augmentin than amoxicillin alone.
Why does Augmentin cause diarrhea? The simple answer: it can do its job too well.
While Augmentin goes to work fighting harmful bacteria, it can do the same to good bacteria that live naturally in your gut. Without these good bacteria, the ability to digest normally may be interrupted. On top of that, the clavulanate part of Augmentin can speed up how quickly your gut moves. This can also lead to diarrhea.
Diarrhea typically goes away once your Augmentin prescription is finished. There is also some research that suggests certain probiotics can help prevent and manage diarrhea. But if diarrhea is bothersome or overwhelming, you may want to ask your prescriber if they can adjust your treatment regimen.
It’s less common, but all antibiotics can raise the risk of Clostridioides difficile (C. diff) diarrhea. This is a type of infectious diarrhea that needs quick medical treatment. Preventing and managing C. diff diarrhea is discussed in another GoodRx Health article.
Augmentin (amoxicillin / clavulanate) dosages: Read about common Augmentin dosages for adults and kids, along with tips on how to take it correctly.
How much does Augmentin cost? Learn more about the cost of Augmentin without insurance and how to save.
Taking antibiotics: Hear from physicians about when you should and shouldn’t take an antibiotic.
2. Nausea and vomiting
Many medications can be irritating to the stomach and cause discomfort. Augmentin is no exception. About 3% of people taking Augmentin in initial studies reported nausea. Vomiting was less common.
If you have nausea or vomiting while taking Augmentin, there are ways to manage your symptoms:
Take your medication with a meal or snack.
Drink plenty of water.
Avoid spicy or fried foods.
Consider trying ginger, peppermint, or acupressure treatments.
Ask your pharmacist about over-the-counter medications for nausea.
Thankfully, these stomach-related side effects don’t usually last for long. They should go away after completing your course of medication.
3. Skin rashes
Skin rashes affected about 3% of people who took Augmentin in initial studies. These rashes may cause small, itchy bumps on your skin. They usually start on the chest or back and spread to the arms and legs. This is not usually related to an allergic reaction.
The risk of skin rashes is higher if you’re actually sick with a virus, not a bacteria. For example, one study found that up to nearly 70% of people sick with mononucleosis (“mono”) may experience a rash if they recently took amoxicillin. The virus appears to make people more sensitive to Augmentin and related antibiotics.
Another skin condition, called Stevens-Johnson syndrome (SJS), is a rare but serious type of rash that’s been reported. It causes the skin to blister and peel. This can lead to serious issues, such as skin infection, trouble breathing, and pain in different parts of your body. If Augmentin is causing symptoms of SJS, you should stop taking it and get emergency medical help as soon as you can.
Since skin rashes vary by situation, it’s a good idea to check in with a healthcare professional if you develop one.
4. Liver changes
There have been a number of reports of connecting Augmentin to medication-related liver problems. It can sometimes affect your liver function, but it’s typically not serious.
Liver injury can show up during and after treatment with Augmentin, but you may not notice any symptoms. In more advanced cases, you may notice fatigue, a low fever, and abdominal pain. Itchiness and yellowing skin or eyes could follow.
Thankfully, liver changes from Augmentin are usually temporary and reversible. But be sure to let your prescriber know right away if you see any of the symptoms described above. They may run tests to keep tabs on your liver health.
What’s more, certain groups of people are more likely to develop liver issues. If you have one or more of these risk factors, your prescriber may want to watch you more closely:
History of liver problems, like hepatitis
Advanced age
Male
Have taken multiple courses of Augmentin in quick succession
Long-term treatment with Augmentin
5. Yeast infections
Yeast infection, or candidiasis, is another possible side effect of Augmentin. This is a fungal infection that can develop in the vagina and other moist places, such as the mouth and underarms.
Fungi and bacteria live together naturally on and in your body. But antibiotics, which target bacteria, don’t kill fungi. When bacteria in the body die, it leaves room for fungi spread out. This can result in overgrowth and a fungal infection.
Again, this isn’t common. And yeast infections can usually be avoided with good hygiene — like washing often and avoiding wearing wet clothing for long periods of time.
If you do develop symptoms of a yeast infection, your prescriber may recommend stopping or changing your antibiotic in order to manage it. Yeast infections are generally very treatable with antifungal medications, such as fluconazole (Diflucan).
6. Black hairy tongue
The name sounds scary, but black hairy tongue (BHT) is a harmless side effect that happens to some people who take Augmentin. Affected people may notice that their taste buds appear longer and darker than normal. Bad breath can also appear.
BHT is not a very common side effect. And the reason why it happens is not entirely clear. One theory is that using antibiotics may change the balance of harmless bacteria that grow normally in the mouth.
There is not much you can do about this side effect. But caring for your mouth by brushing your teeth and tongue can help prevent it. It should resolve soon after finishing your Augmentin prescription.
Frequently asked questions
Possibly. Augmentin comes in many doses with various amounts of the helper molecule clavulanate. Different amounts of clavulanate compared to amoxicillin seem to cause different rates of diarrhea. What’s more, the extended-release (ER) form of Augmentin is thought to cause diarrhea more often than the immediate-release (IR) version.
Augmentin starts fighting bacteria within 1 to 1.5 hours of your first dose. But it may take a day or two before you start feeling better. Everyone’s recovery timeline is a little different. It’s important to keep taking Augmentin exactly as prescribed, even if your symptoms improve, to make sure the infection clears up completely.
You should try to avoid taking Augmentin on an empty stomach. It’s better to take Augmentin with food or at the start of a meal. This helps your body absorb the medication better and lowers the chance of an upset stomach.
Possibly. Augmentin comes in many doses with various amounts of the helper molecule clavulanate. Different amounts of clavulanate compared to amoxicillin seem to cause different rates of diarrhea. What’s more, the extended-release (ER) form of Augmentin is thought to cause diarrhea more often than the immediate-release (IR) version.
Augmentin starts fighting bacteria within 1 to 1.5 hours of your first dose. But it may take a day or two before you start feeling better. Everyone’s recovery timeline is a little different. It’s important to keep taking Augmentin exactly as prescribed, even if your symptoms improve, to make sure the infection clears up completely.
You should try to avoid taking Augmentin on an empty stomach. It’s better to take Augmentin with food or at the start of a meal. This helps your body absorb the medication better and lowers the chance of an upset stomach.
The bottom line
Augmentin (amoxicillin / clavulanate) is a widely used antibiotic. The most common Augmentin side effects are stomach-related. Diarrhea, nausea, and vomiting tend to be the most frequent complaints. Serious Augmentin side effects include liver problems and blistering skin rashes, but they’re rare overall. Make sure to let your healthcare team know if you develop any side effects that are worrisome or don’t go away.
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References
Gillies, M., et al. (2015). Common harms from amoxicillin: A systematic review and meta-analysis of randomized placebo-controlled trials for any indication. Canadian Medical Association Journal.
Gurvits, G. E., et al. (2014). Black hairy tongue syndrome. World Journal of Gastroenterology.
Kuehn, J., et al. (2015). Reported rates of diarrhea following oral penicillin therapy in pediatric clinical trials. The Journal of Pediatric Pharmacology and Therapeutics.
Marín, L. H., et al. (2025). Drug-induced enterocolitis, a new condition under consideration. Allergologia et Immunopathologia.
Mohsen, S., et al. (2020). Update on the adverse effects of antimicrobial therapies in community practice. Canadian Family Physician.
Ónodi-Nagy, K., et al. (2015). Amoxicillin rash in patients with infectious mononucleosis: Evidence of true drug sensitization. Allergy, Asthma & Clinical Immunology.
Ren, J., et al. (2020). Antibiotic-induced black hairy tongue: Two case reports and a review of the literature. Journal of International Medical Research.
Sandoz. (2025). Amoxicillin and clavulanate potassium tablet, film coated [package insert].
Uto, L. R., et al. (2023). Clavulanic acid. StatPearls.
