Amoxicillin/Clavulanate Side Effects: What's Normal and What's Not

Amoxicillin/Clavulanate (brand name Augmentin) is one of the most widely prescribed antibiotics in the world. Like all medications, it can cause side effects — but most are mild and go away on their own. Knowing what to expect can help you feel more confident about your treatment and recognize when something needs medical attention.

This guide covers the common side effects, the rare but serious ones, and exactly when you should call your doctor.

What Is Amoxicillin/Clavulanate?

Amoxicillin/Clavulanate is a combination antibiotic that pairs Amoxicillin (a penicillin-type antibiotic) with Clavulanate (a beta-lactamase inhibitor). Together, they fight a broader range of bacteria than Amoxicillin alone. It's used to treat sinus infections, ear infections, skin infections, urinary tract infections, and more.

Common Side Effects

Most people who take Amoxicillin/Clavulanate experience only mild side effects, if any. The Clavulanate component is responsible for most of the gastrointestinal symptoms. According to FDA labeling, common side effects include:

• Diarrhea — the most common side effect, affecting up to 34% of patients. This is largely caused by the Clavulanate component.
• Nausea and vomiting — usually mild and often preventable by taking the medication with food
• Abdominal pain or cramping — stomach discomfort is common but usually temporary
• Skin rash — a non-serious rash occurs in some patients; this is different from an allergic reaction (see below)
• Vaginal yeast infections — antibiotics can disrupt normal flora, leading to yeast overgrowth
• Headache — reported by some patients during treatment

These side effects are generally mild and resolve once you finish your course of antibiotics. Taking Amoxicillin/Clavulanate with food is the single best way to reduce stomach-related side effects.

Serious Side Effects

Serious side effects from Amoxicillin/Clavulanate are rare, but they do happen. Seek medical attention immediately if you experience any of the following:

Severe Allergic Reactions (Anaphylaxis)

Signs include difficulty breathing, swelling of the face, lips, tongue, or throat, hives, and a rapid heartbeat. This is a medical emergency — call 911 or go to the nearest ER. People with a known allergy to penicillin or cephalosporins should not take Amoxicillin/Clavulanate.

Clostridioides difficile (C. diff) Infection

Antibiotics can disrupt gut bacteria and allow C. difficile to overgrow. Symptoms include watery diarrhea (3 or more times per day), fever, abdominal pain, and blood or mucus in stool. This can occur during treatment or even weeks after finishing the antibiotic. Contact your doctor immediately if you develop severe or persistent diarrhea.

Liver Problems (Cholestatic Hepatitis)

Amoxicillin/Clavulanate can rarely cause liver inflammation, which may appear as yellowing of the skin or eyes (jaundice), dark urine, or severe fatigue. This can occur weeks after stopping the medication. Older adults and people who take longer courses are at higher risk.

Stevens-Johnson Syndrome (SJS)

This is an extremely rare but life-threatening skin reaction. Signs include a spreading rash with blistering, peeling skin, sores in the mouth or eyes, and fever. Stop taking the medication and seek emergency care immediately.

Seizures

Seizures have been reported in patients taking high doses of Amoxicillin/Clavulanate, particularly those with kidney impairment. If you have a history of seizures or kidney problems, make sure your doctor knows before starting this medication.

Specific Populations

Children

Amoxicillin/Clavulanate is widely used in children and is generally well tolerated. Diarrhea and diaper rash are the most common side effects in pediatric patients. The liquid suspension form is flavored but the Clavulanate component can still cause stomach upset. Giving it with food helps.

Pregnant and Breastfeeding Women

Amoxicillin/Clavulanate is classified as Pregnancy Category B, meaning it's generally considered safe during pregnancy. It does pass into breast milk in small amounts but is generally considered compatible with breastfeeding. Always discuss with your doctor.

Older Adults

Elderly patients may be more susceptible to liver-related side effects and may need dose adjustments if kidney function is reduced. The risk of cholestatic hepatitis increases with age and longer treatment durations.

People with Kidney Problems

If you have reduced kidney function, your doctor may prescribe a lower dose. The extended-release formulation (Augmentin XR) is contraindicated if your creatinine clearance is below 30 mL/min.

How to Manage Common Side Effects

Here are practical tips to minimize discomfort while taking Amoxicillin/Clavulanate:

• Take it with food — this is the most important step to prevent nausea, vomiting, and diarrhea
• Stay hydrated — drink plenty of water, especially if you're experiencing diarrhea
• Consider probiotics — some studies suggest probiotics (like Lactobacillus) may help reduce antibiotic-associated diarrhea. Take them at least 2 hours apart from your antibiotic.
• Use OTC remedies carefully — avoid anti-diarrheal medications like loperamide (Imodium) without talking to your doctor first, as they can mask symptoms of C. diff
• Watch for yeast infections — OTC antifungal treatments are available if you develop a vaginal yeast infection
• Don't skip doses or stop early — completing the full course helps prevent antibiotic resistance and recurrent infection

For more information on drug interactions to be aware of, check our dedicated guide.

Final Thoughts

Amoxicillin/Clavulanate is a safe and effective antibiotic for millions of people each year. Most side effects are mild gastrointestinal symptoms that improve with food and resolve after treatment ends. Serious side effects are rare but important to recognize.

The bottom line: take it with food, finish the full course, stay hydrated, and call your doctor if you develop severe diarrhea, signs of an allergic reaction, or jaundice. If you need help finding this medication at a pharmacy near you, Medfinder can help you locate Amoxicillin/Clavulanate in stock.