Amoxicillin-clavulanate: what it treats, how to take it, side effects
Last updated September 3, 2026.
Amoxicillin-clavulanate is a two-part antibiotic - amoxicillin kills the bacteria, and clavulanic acid stops the bacteria from destroying the amoxicillin. You may know it as Augmentin. It is what gets prescribed when plain amoxicillin would lose the fight.
What does it treat?
Bacterial infections of the ears, lungs, sinuses, skin, and urinary tract. It does not work for colds, flu, or other viral infections - using it when it is not needed breeds resistant bacteria.
How do you take it?
With a meal or snack, every 8 to 12 hours - 2 to 3 times a day - at the same times every day. The food is not optional advice; it is how the stomach tolerates it. Chewable tablets get chewed completely; the liquid gets shaken and measured with a real dosing device, kept in the refrigerator, and discarded after 10 days. You should feel better within the first few days - if not, call your doctor. Finish the entire prescription even when you feel better. Missed dose: take it when you remember unless the next one is close; never double up.
Side effects to know
- Common: diarrhea, upset stomach, vomiting, and vaginal itching or discharge.
- Serious - call your doctor immediately: watery or bloody stools, stomach cramps, or fever during treatment or up to 2 or more months after stopping; severe vomiting 1 to 4 hours after a dose; rash, itching, hives; trouble breathing or swallowing, wheezing, or swelling of the face, throat, tongue, lips, or eyes; peeling, blistering, or shedding skin; a return of fever, sore throat, or chills; and the liver cluster - yellowing skin or eyes, right upper stomach pain, fatigue, loss of appetite, easy bleeding or bruising, or dark urine.
Who should not take it?
Anyone who has had liver problems on this drug before - MedlinePlus says your doctor may rule it out. Flag mononucleosis (the combination produces a famous rash), kidney or liver disease, allergies, asthma, hay fever, and hives. If you have phenylketonuria, the chewable tablets and suspension contain aspartame. One practical warning: this medication can make oral contraceptives - pills, patches, rings, injections - less effective, so a backup method for the course. If you become pregnant, call your doctor.
When is it an emergency?
Trouble breathing, wheezing, or swelling of the face, lips, tongue, or throat is a 911 call - penicillin-family reactions can escalate fast. Bloody diarrhea with cramps and fever means same-day care. For an overdose, call Poison Control at 1-800-222-1222. Pymander's escalation routing is built and tested specifically for this class of decision; see the safety architecture working paper.
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Common questions
Why does Augmentin affect my birth control pills?
It can lower their effectiveness. MedlinePlus says amoxicillin and clavulanic acid may decrease the effectiveness of oral contraceptives - pills, patches, rings, and injections - and that you will need another method of contraception while taking it. Plan the backup before the first dose, not mid-course.
Why do I have to take Augmentin with food?
Your stomach needs the buffer. MedlinePlus says take it with a meal or snack every 8 to 12 hours - the clavulanic acid half is rough on an empty stomach, and food smooths the nausea and diarrhea that top the common-effects list. Breakfast and dinner make the twice-daily rhythm easy.
Why did my doctor choose Augmentin instead of plain amoxicillin?
Some bacteria carry a shield. The clavulanic acid half blocks the enzyme - beta-lactamase - that resistant bacteria use to destroy amoxicillin. MedlinePlus explains the pairing directly: amoxicillin stops bacterial growth, clavulanic acid stops bacteria from breaking it down. If you were prescribed the combination, plain amoxicillin was judged likely to fail.
What is the mono warning with Augmentin?
If you have mononucleosis, this drug can produce a widespread rash - MedlinePlus says to tell your doctor if you have mono before starting. It is not an allergy, but it looks alarming and it changes what gets prescribed. Undiagnosed mono plus Augmentin is how people get wrongly labeled penicillin-allergic for life.
Can I drink alcohol while taking Augmentin?
Neither the label nor MedlinePlus gives this combination specific alcohol language. Alcohol worsens the stomach upset that is already the most common complaint, and you are recovering from an infection. Skip it for the course - it is short.
How long does Augmentin liquid keep?
Ten days. MedlinePlus says keep the liquid in the refrigerator, tightly closed, and dispose of any unused medication after 10 days. If the course is over, the leftover goes - do not save it for the next illness, because expired suspension is not full-strength and the next illness may need something else entirely.