Amoxicillin and amoxicillin/clavulanate (Augmentin): a clinical guide for patients

Amoxicillin and amoxicillin/clavulanate: what they are, how to take them, risks, and alternatives

Amoxicillin is one of the most commonly prescribed antibiotics worldwide. It belongs to the penicillin family and is valued for its effectiveness, safety profile, and flexibility in both adults and children. Its combination with clavulanic acid marketed under brand names such as Augmentin extends its spectrum of action, helping overcome resistance in bacteria that produce enzymes called β-lactamases. Together, these drugs form a cornerstone of outpatient treatment for respiratory tract infections, ear infections, dental infections, and other community-acquired bacterial illnesses.

For patients, however, the differences between plain amoxicillin and Augmentin are not always clear. Which one is right for a sore throat or a sinus infection? How should the medication be taken – before meals, with meals, or at fixed intervals? What side effects should be expected, and when is it important to contact a doctor urgently?

This guide provides a patient-friendly overview of what these antibiotics are, when they are prescribed, how to take them correctly, possible risks, and how digital health tools can support safe use. It draws on evidence-based guidelines from the CDC, IDSA, AAP, FDA, and NIH.

Need help accessing treatment? See how to get amoxicillin legally and safely in the US.

Brief summary

Amoxicillin is a penicillin antibiotic often prescribed for strep throat, sinus infections, ear infections, and some dental or lung infections. It works well against common bacteria and is usually well tolerated.

Amoxicillin/clavulanate (Augmentin) combines amoxicillin with clavulanic acid. Clavulanate blocks enzymes (β-lactamases) that can inactivate amoxicillin, making the drug effective against a wider range of bacteria. Doctors typically choose Augmentin for more resistant infections, such as animal bites, complicated sinus or ear infections, or dental abscesses.

Typical adult dosages:

Amoxicillin 500 mg every 8 hours, or 875 mg every 12 hours.

Augmentin 875/125 mg every 12 hours.
Treatment length is usually 5–10 days, depending on the infection.

Children’s doses are calculated by weight, often using liquid suspensions (e.g., 250 mg/5 ml or 400 mg/5 ml).

When to call a doctor urgently:

Signs of allergy (rash, swelling, difficulty breathing).

Severe or persistent diarrhea.

No improvement after 2–3 days of correct use.

Any reaction suggesting C. difficile infection (fever, abdominal cramps, watery diarrhea).

To put it shortly: Amoxicillin is often first-line; Augmentin is for more resistant cases. Take as directed, finish the course, and consult your doctor if unsure.

What are these drugs

Amoxicillin

Amoxicillin is a broad-spectrum penicillin antibiotic. Like other β-lactams, it works by inhibiting bacterial cell wall synthesis, causing bacteria to weaken and die. It is effective against many Gram-positive organisms such as Streptococcus pyogenes (strep throat) and Streptococcus pneumoniae (sinusitis, pneumonia), as well as some Gram-negative bacteria like Haemophilus influenzae and Escherichia coli.

Available forms include tablets, capsules, dispersible tablets, and oral suspensions (liquid forms for children). The suspension comes in different strengths, often 125 mg/5 ml, 250 mg/5 ml, or 400 mg/5 ml, allowing weight-based dosing in pediatrics. Since amoxicillin is relatively gentle on the gut and has good absorption, it is often chosen as a first-line antibiotic for upper respiratory tract and ear infections in both adults and children.

Amoxicillin/clavulanate (Augmentin)

Some bacteria produce enzymes called β-lactamases that can destroy amoxicillin before it has a chance to work. To overcome this, amoxicillin is sometimes combined with clavulanic acid, a β-lactamase inhibitor. This combination is marketed under brand names such as Augmentin.

Clavulanic acid does not kill bacteria directly but protects amoxicillin, allowing it to remain effective against resistant strains. This makes Augmentin useful for infections caused by organisms likely to produce β-lactamases, such as certain strains of Staphylococcus aureus, H. influenzae, Moraxella catarrhalis, and anaerobic bacteria involved in dental or bite infections.

Formulations include tablets (commonly 875/125 mg) and oral suspensions (e.g., 400/57 mg per 5 ml for children). Because clavulanate may cause more gastrointestinal side effects, Augmentin is usually reserved for situations where its broader coverage is truly needed.

Indications

Amoxicillin and amoxicillin/clavulanate are both valuable antibiotics, but their use depends on the infection type and the likelihood of resistant bacteria.

Streptococcal pharyngitis (strep throat). Amoxicillin is often the first-line choice because it reliably targets Streptococcus pyogenes. Typical treatment lasts 10 days to ensure eradication and prevent complications such as rheumatic fever.

Acute bacterial sinusitis. Most sinus infections are viral, but when bacterial signs are present (fever, persistent symptoms >10 days, severe pain, or double worsening), antibiotics may be justified. Amoxicillin is generally first-line, while Augmentin is used if resistance is suspected, symptoms are severe, or recent antibiotics were taken.

Otitis media (ear infection). In children and adults, amoxicillin is usually the initial treatment. Augmentin is preferred if the child attends daycare, has received amoxicillin in the last month, or if H. influenzae or M. catarrhalis resistance is suspected.

Community-acquired pneumonia. Amoxicillin can be effective against S. pneumoniae in otherwise healthy patients with mild pneumonia. However, broader coverage (e.g., with Augmentin or combination therapy) is considered if mixed pathogens are possible.

Animal and human bites. Augmentin is recommended because bite wounds often contain β-lactamase–producing anaerobes that amoxicillin alone cannot cover.

Dental and gum infections. Both drugs are used, but Augmentin is often chosen when anaerobic bacteria are involved, such as in abscesses.

Urinary tract infections. Amoxicillin is not usually first-line, since resistance among E. coli is common. Other antibiotics are often preferred unless culture results confirm susceptibility.

In practice, clinicians weigh infection severity, resistance risk, and recent antibiotic use when deciding between amoxicillin and Augmentin. Whenever possible, narrower-spectrum amoxicillin is used first to preserve broader-spectrum drugs for when they are truly needed.

Dosages and regimens

Adults

For adults, the most common regimen of amoxicillin for respiratory tract infections is either 500 mg three times a day or 875 mg twice a day. In cases of streptococcal pharyngitis, the course typically lasts ten days, using 500 mg twice daily or 250 mg three times daily. Pneumonia may require higher dosing, up to 1 gram three times daily. When amoxicillin is combined with clavulanate, the usual prescription is 875/125 mg every twelve hours. For severe or resistant infections, an extended-release formulation of 2,000/125 mg twice daily may be chosen. Dental abscesses and bite wounds are also generally treated with the 875/125 mg strength twice daily.

Children

In children, dosing is always calculated by weight. For routine infections, amoxicillin is usually prescribed at 40–50 mg per kilogram of body weight per day, divided into two or three doses. For ear infections and pneumonia, pediatricians often choose higher doses of 80–90 mg/kg/day to ensure effectiveness against resistant Streptococcus pneumoniae. With Augmentin, the amoxicillin component is dosed at 45 mg/kg/day for mild cases, rising to 90 mg/kg/day for difficult infections. The amount of clavulanate is kept as low as possible to reduce gastrointestinal upset. Suspensions make dosing easier for children, with typical strengths of 125, 250, or 400 mg per 5 ml for amoxicillin, and 200/28.5 mg or 400/57 mg per 5 ml for Augmentin.

Common scenarios

Whatever the formulation, the guiding principles remain the same: doses should be evenly spaced, usually every 8 or 12 hours, so that blood levels stay constant. Augmentin should always be taken with food to reduce stomach upset, whereas plain amoxicillin can be taken with or without meals. Most importantly, the full course must be completed, even if symptoms improve early, since stopping too soon encourages resistant bacteria to survive.

Patients with kidney disease may require dose adjustments, which should always be decided by a physician. Self-adjusting or skipping doses undermines treatment and increases the risk of both failure and resistance.

How to take correctly

The effectiveness of antibiotics depends not only on the right drug and dose but also on how patients actually take them. Even small lapses, like skipping doses, stopping early, or taking medicine irregularly, can reduce the benefit and increase the risk of resistance.

Timing matters. Amoxicillin and Augmentin work best when taken at evenly spaced intervals to keep blood levels stable. If the prescription says every 8 hours, that means three times a day at roughly the same times; every 12 hours means twice daily, morning and evening. Try to link the schedule to routine activities like breakfast or bedtime to make it easier to remember.

With or without food. Amoxicillin alone can be taken with or without meals, though some people find it gentler on the stomach when not taken on an empty stomach. Augmentin, by contrast, should always be taken with food to minimize gastrointestinal side effects caused by clavulanate.

Do not stop early. Symptoms often improve within a couple of days, but the infection may not be fully cleared. Ending treatment early risks relapse and encourages resistant bacteria. Always finish the course unless a doctor specifically instructs otherwise.

Missed doses. If you forget a dose, take it as soon as you remember—unless it’s nearly time for the next one. In that case, skip the missed dose and continue as scheduled. Never double up.

Other precautions. Avoid saving leftover antibiotics for future use or sharing them with others. Both practices are unsafe and contribute to inappropriate antibiotic use.

Correct antibiotic use protects both the individual patient and the wider community by preserving the effectiveness of these vital drugs.

To stay on schedule and avoid missed doses, explore IoT adherence tools for safer antibiotic use.

Side effects and allergies

Amoxicillin and Augmentin are generally well tolerated, but like all antibiotics they can cause side effects. The most frequent are digestive issues. Amoxicillin may lead to nausea, loose stools, or mild diarrhea. Augmentin, because of its clavulanate component, is more likely to upset the stomach; taking it with food usually helps.

Skin rashes are another common reaction. Not all mean allergy, non-itchy rashes sometimes appear in children with viral infections such as mononucleosis. But itchy rashes, hives, or swelling should always raise concern for allergy.

True allergic reactions are uncommon but serious. Sudden swelling of the lips, face, or throat, trouble breathing, or widespread hives require immediate medical attention, and usually mean avoiding all penicillin-family antibiotics in the future.

Less common risks include liver irritation (more often with Augmentin), C. difficile infection with severe diarrhea and fever, and yeast infections due to microbiome disruption. Most patients experience only mild, short-lived symptoms, but any severe or unusual reaction warrants prompt medical review.

Interactions and special situations

Although amoxicillin and amoxicillin/clavulanate are generally safe, they can interact with other medicines and sometimes alter their effects. Knowing about these interactions helps patients avoid unnecessary risks.

One important interaction is with oral anticoagulants such as warfarin. Amoxicillin may change gut bacteria that help regulate vitamin K, potentially increasing bleeding risk. Patients on blood thinners should have their INR monitored more closely when starting or stopping these antibiotics.

Methotrexate, used for cancer and autoimmune conditions, can also be affected. Amoxicillin can reduce its clearance from the body, leading to higher levels and possible toxicity. Doctors may adjust methotrexate dosing or use a different antibiotic in these cases.

Allopurinol, commonly prescribed for gout, may increase the likelihood of skin rashes when taken with amoxicillin. This does not necessarily mean an allergy, but it can complicate treatment and needs medical review.

Oral contraceptives are a frequent concern. Current evidence suggests amoxicillin does not significantly reduce their effectiveness, but some guidelines still advise using backup contraception during antibiotic courses, particularly if diarrhea or vomiting occurs.

As with many antibiotics, combining with other broad-spectrum agents can disturb the gut microbiome, raising the risk of side effects such as diarrhea or yeast infections.

Finally, alcohol is not strictly contraindicated with these drugs, but drinking may worsen gastrointestinal upset and impair adherence, so moderation is best. In all cases, patients should inform their doctor or pharmacist of all medicines, vitamins, and supplements they are taking. Open communication ensures interactions are identified and managed safely.

Amoxicillin vs Augmentin (comparison)

Amoxicillin and amoxicillin/clavulanate (Augmentin) share the same antibiotic base but are not interchangeable. Amoxicillin is the simpler choice, effective against many common bacteria and generally well tolerated, with fewer gastrointestinal problems. For that reason, it is often prescribed first for uncomplicated infections such as strep throat, ear infections, or mild community-acquired pneumonia.

Augmentin combines amoxicillin with clavulanic acid, a compound that blocks bacterial enzymes called β-lactamases. These enzymes can destroy plain amoxicillin, so the combination extends activity against bacteria such as Haemophilus influenzae or anaerobes common in dental infections and bite wounds. Its broader coverage makes it valuable in resistant or mixed infections, though it tends to cause more stomach upset and diarrhea.

In practice, doctors usually begin with amoxicillin when the bacteria are expected to respond. Augmentin is chosen when there is greater severity, recent antibiotic exposure, or local resistance patterns suggesting that a stronger option is required. The trade-off is clear: amoxicillin is narrower and gentler, while Augmentin is broader but harsher.

Antibiotic stewardship (safe and reasonable use)

Amoxicillin and Augmentin are effective medicines, but their value depends on using them wisely. Antibiotic stewardship is the effort to preserve these drugs by ensuring they are prescribed only when truly necessary and in the right way. Many common illnesses, such as colds or flu, are viral and will not improve with antibiotics. Unnecessary use increases the risk of side effects for the patient and contributes to the global problem of resistance.

Responsible use means finishing the full course, not saving leftover tablets, and never sharing prescriptions. Doctors choose between amoxicillin and Augmentin based on the likely bacteria involved, the severity of infection, and local resistance data. Patients play an equal role by following instructions carefully and reporting any problems promptly. Together, these practices protect both individual health and the long-term effectiveness of antibiotics.

Digital tools for safe antibiotic use

Digital health technologies are beginning to support safer, more effective antibiotic use. One area is medication reminders: smartphone apps and smart pill bottles can prompt patients to take each dose at the correct time, helping to prevent skipped or delayed tablets. For parents managing children’s liquid suspensions, apps can also log exact doses and send alerts to multiple caregivers.

Electronic health records and patient portals add another layer by linking prescriptions to educational materials. Patients can check instructions, watch short videos on how to measure suspensions correctly, and receive alerts if an antibiotic course is about to run out. Some health systems now use stewardship dashboards that track antibiotic prescribing patterns in real time. For patients, this means their doctors receive gentle “digital nudges” to prescribe appropriately, reducing unnecessary use of broad-spectrum drugs like Augmentin.

These tools do not replace professional advice, but they support better adherence, clearer communication, and safer prescribing, all of which help protect the usefulness of antibiotics.

Curious what actually improves adherence? Compare smart pill bottles vs. app-only reminders.

FAQ

Can I take amoxicillin or Augmentin for a cold or flu?

No. These illnesses are viral, and antibiotics will not help. Using them unnecessarily only increases the risk of side effects and resistance.

Should I take the tablets with food?

Amoxicillin can be taken with or without meals. Augmentin is best taken with food to reduce stomach upset.

What if I miss a dose?

Take it as soon as you remember, unless it is almost time for the next one. Do not double the dose, just return to your regular schedule.

Are diarrhea and stomach pain normal?

Mild digestive symptoms are common, especially with Augmentin. Severe or watery diarrhea, especially with fever or abdominal cramps, requires urgent medical advice to rule out C. difficile infection.

Can I drink alcohol during treatment?

Moderate alcohol does not interact directly with these drugs, but it can worsen stomach irritation and delay recovery. It is safest to limit or avoid alcohol until treatment is finished.

References

Centers for Disease Control and Prevention. (2021). Antibiotic use: Amoxicillin and amoxicillin/clavulanate fact sheet. U.S. Department of Health and Human Services, CDC. https://www.cdc.gov/antibiotic-use

Clinical and Laboratory Standards Institute. (2021). Performance standards for antimicrobial susceptibility testing (31st ed.). CLSI.

Infectious Diseases Society of America. (2012). IDSA clinical practice guideline for the diagnosis and management of group A streptococcal pharyngitis. Clinical Infectious Diseases, 55(10), 1279–1282. https://doi.org/10.1093/cid/cis847

National Institute for Health and Care Excellence. (2019). Amoxicillin: Medicines information. NICE. https://www.nice.org.uk

World Health Organization. (2021). WHO model list of essential medicines – 22nd list. WHO. https://www.who.int/publications/i/item/WHO-MHP-HPS-EML-2021.02