Amoxicillin Dosage for Adults and Children: What the Research Says

Key findings at a glance

• Adults: The FDA label covers a total daily range of 750 to 1,750 mg, usually given as 500 mg or 875 mg every 12 hours, or 250 mg or 500 mg every 8 hours, depending on the infection and how severe it is.
• Children: Doses are calculated by body weight (mg/kg/day). For ear infections and pneumonia, pediatric guidelines favor a higher dose of about 80 to 90 mg/kg/day split into two doses.
• Dose timing: A Cochrane review of 5 trials in 1,601 children found twice-daily amoxicillin worked about as well as three-times-daily dosing for ear infections.
• Course length: Two large trials (SCOUT-CAP, 2022, and CAP-IT, 2021) support shorter courses for uncomplicated childhood pneumonia. But in children under 2 with ear infections, a 5-day course did worse than 10 days (NEJM, 2016).
• Kidneys matter: People with severe kidney impairment (GFR under 30 mL/min) should not get the 875 mg tablet, according to the label.

Amoxicillin dosage is not one number. It shifts with your age, your weight, the infection being treated, and how well your kidneys clear the drug. That is why two people can leave the same pharmacy with very different instructions on their bottles, and both can be right.

This report pulls together what the official FDA prescribing information says, what pediatric and infectious disease guidelines recommend, and what clinical trials have found about dose size, dose timing, and course length. You will also find a worked example of how a child’s weight turns into milliliters of liquid medicine, plus practical answers on missed doses and storage.

One ground rule before we start: everything here explains how prescribers think about dosing. It is not a guide to dosing yourself or your child. Your prescription label is the instruction that counts, and your pharmacist is the best person to answer questions about it. If you want the bigger picture first, our overview of which infections amoxicillin treats is a good starting point.

Standard adult dosing per the FDA label

The FDA-approved label for amoxicillin capsules, tablets, and oral suspension sets amoxicillin dosage for adults by the part of the body that is infected and by severity. “Adult” here also includes children who weigh 40 kg (about 88 pounds) or more, since they are dosed the same way as grown-ups.

The two most common adult schedules are amoxicillin 500 mg and 875 mg tablets taken every 12 hours. The 500 mg capsule or tablet is also used every 8 hours for more serious infections. The table below summarizes the label figures.

Infection	Severity	Every 12 hours	Every 8 hours
Ear, nose, throat; skin; genitourinary tract	Mild to moderate	500 mg	250 mg
Ear, nose, throat; skin; genitourinary tract	Severe	875 mg	500 mg
Lower respiratory tract (for example, bronchitis or pneumonia)	Mild, moderate, or severe	875 mg	500 mg

Notice that every 12-hour dose has an every 8-hour partner. The total amount per day is similar either way. For example, 875 mg twice daily is 1,750 mg a day, and 500 mg three times daily is 1,500 mg a day. Prescribers often pick the twice-daily option because it is easier to stick with.

Some infections fall outside this table. Dental infections, for instance, are usually managed according to dental guidance rather than a body-system category on the label. Our guide to amoxicillin for tooth infections covers that situation separately.

H. pylori combination regimens

Amoxicillin is also part of combination treatment for Helicobacter pylori, the stomach bacterium linked to ulcers. Here the dose is higher than usual and is always paired with other medicines. The label lists two 14-day adult regimens:

Regimen	Amoxicillin	Paired with	Schedule
Triple therapy	1 gram	Clarithromycin 500 mg + lansoprazole 30 mg	All twice daily for 14 days
Dual therapy	1 gram	Lansoprazole 30 mg	Both three times daily for 14 days

These are label regimens. A gastroenterologist may choose a different combination based on local resistance patterns and your treatment history, so ask your doctor how your plan was chosen.

Dose changes for reduced kidney function

Your kidneys remove most amoxicillin from the body. When they work slowly, the drug can build up. The label says most people with kidney problems need no change, but severe impairment does call for adjustment. The label measures kidney function with glomerular filtration rate (GFR), a number your doctor gets from routine blood work.

Kidney function	Typical label adjustment
GFR 30 mL/min or higher	Usually no change from standard dosing
GFR 10 to 30 mL/min	500 mg or 250 mg every 12 hours, depending on severity
GFR under 10 mL/min	500 mg or 250 mg every 24 hours
Hemodialysis	500 mg or 250 mg every 24 hours, plus an extra dose during and at the end of dialysis

If you have chronic kidney disease, make sure every prescriber and pharmacist knows. It is a common reason an amoxicillin dosage looks “lower than normal,” and that lower dose is intentional.

Children’s dosing is based on weight

For kids, amoxicillin dosage for children is written as milligrams per kilogram of body weight per day, shortened to mg/kg/day. The prescriber multiplies the child’s weight by that number to get a daily total, then splits it into two or three doses. This approach keeps the amount of drug in a small body roughly in line with what an adult gets, adjusted for size.

Weight-based dosing is common in pediatrics, not just for antibiotics. If you have seen it with a deworming medicine, our article on albendazole dosage for children shows how a different drug handles the same problem in a different way.

What the FDA label lists for children

The label gives separate figures for children older than 3 months who weigh under 40 kg, and for babies 12 weeks old or younger.

Group and infection	Divided every 12 hours	Divided every 8 hours
Over 3 months, under 40 kg: ear, nose, throat, skin, or genitourinary, mild to moderate	25 mg/kg/day	20 mg/kg/day
Over 3 months, under 40 kg: ear, nose, throat, skin, or genitourinary, severe	45 mg/kg/day	40 mg/kg/day
Over 3 months, under 40 kg: lower respiratory tract, any severity	45 mg/kg/day	40 mg/kg/day
Newborns and infants 12 weeks or younger	Up to 30 mg/kg/day	Not listed

The cap for young infants exists because their kidneys are still maturing and clear the drug more slowly. The label also notes that strep throat caused by Streptococcus pyogenes should be treated for at least 10 days to help prevent rheumatic fever.

Guideline doses that go beyond the label

Many parents are surprised when their child’s amoxicillin dosage is roughly double the label figures above. That is usually deliberate. Professional guidelines, written after the label tables were set, recommend higher amounts of amoxicillin mg/kg for certain infections:

• Acute ear infection (otitis media): The American Academy of Pediatrics (AAP) 2013 guideline recommends high-dose amoxicillin, 80 to 90 mg/kg/day in two divided doses, as the first choice when an antibiotic is needed. See our full guide to amoxicillin for ear infections in kids.
• Community-acquired pneumonia: The 2011 guideline from the Pediatric Infectious Diseases Society and the Infectious Diseases Society of America (PIDS/IDSA) lists 90 mg/kg/day in two doses, or 45 mg/kg/day in three doses, with a maximum of 4 grams a day.
• Strep throat: The IDSA 2012 guideline lists 50 mg/kg once daily (maximum 1,000 mg), or 25 mg/kg twice daily (maximum 500 mg per dose), for 10 days. Our strep throat guide explains why the full course matters.

Guidelines also note that a child’s dose should not climb above the usual adult dose, no matter how much they weigh. That is one reason prescribers cap totals for older, heavier kids.

Worked example: from kilograms to milliliters

Illustrative only. This example is here to help you understand the math on your child’s prescription. It is not a dose to give. Always follow the exact amount printed on your pharmacy label, and ask your pharmacist if anything looks off.

Say a prescriber is treating a 20 kg child (about 44 pounds) with a lower respiratory infection, using the label figure of 45 mg/kg/day divided every 12 hours. The pharmacy dispenses a suspension that contains 400 mg in every 5 mL.

1. Daily total: 20 kg × 45 mg/kg/day = 900 mg per day.
2. Per dose: 900 mg ÷ 2 doses = 450 mg per dose.
3. Strength per mL: 400 mg ÷ 5 mL = 80 mg in each mL.
4. Volume per dose: 450 mg ÷ 80 mg/mL = 5.625 mL, which a pharmacist would typically round to a measurable amount such as 5.6 mL.

If the same child were being treated for an ear infection at the guideline high dose of 90 mg/kg/day, the math changes: 20 × 90 = 1,800 mg a day, or 900 mg per dose, which works out to 11.25 mL of the same suspension twice daily. Same child, same bottle, double the volume. That is why you should never reuse an old dosing amount for a new illness.

Suspensions come in several strengths, including 125 mg/5 mL, 200 mg/5 mL, 250 mg/5 mL, and 400 mg/5 mL. A 5.6 mL dose of one strength is not the same medicine dose as 5.6 mL of another. The prescription label is matched to the bottle you were given, and it is the only number to follow.

What the research says about amoxicillin dosing

Amoxicillin dosage advice has changed over the years as studies tested bigger doses, fewer doses per day, and shorter courses. Here is where the evidence stands on four key questions.

High dose vs standard dose, and resistant pneumococcus

The push toward 80 to 90 mg/kg/day came from Streptococcus pneumoniae (pneumococcus), a leading cause of both ear infections and pneumonia in children. Some strains became less sensitive to penicillin-type drugs. They can still be killed, but only if the drug concentration at the infection site stays high enough for long enough.

The AAP 2013 otitis media guideline explains the reasoning: a high dose produces levels in middle-ear fluid that exceed what is needed to kill pneumococcal strains with intermediate penicillin resistance, and many highly resistant ones. Amoxicillin also stays above that threshold for a larger share of the time between doses, which the authors tie to better outcomes. The guideline adds that wider use of the PCV13 pneumococcal vaccine might reduce the need for high doses in the future.

Is high dose always necessary, though? The UK CAP-IT trial (Bielicki and colleagues, JAMA, 2021) tested exactly that in 824 children aged 6 months and older who were treated for pneumonia after visiting a hospital emergency department or ward. Children got either a lower dose (35 to 50 mg/kg/day) or a higher dose (70 to 90 mg/kg/day). The need for a second antibiotic within 28 days was nearly identical: 12.6% with the lower dose and 12.4% with the higher dose.

That result was considered noninferior, meaning the lower dose was not meaningfully worse. Still, the authors cautioned that disease severity, setting, and recent antibiotic use should shape how the findings are applied. US guidelines have not dropped their high-dose recommendations, and local resistance patterns differ between countries.

Twice daily vs three times daily

Amoxicillin was originally given three times a day. Getting a third dose into a child who is at day care or school is hard, and missed doses are common. So researchers asked whether two larger doses could work as well as three smaller ones.

A 2013 Cochrane systematic review (Thanaviratananich and colleagues) pooled 5 randomized trials with 1,601 children up to age 12 with acute ear infections. It compared once- or twice-daily amoxicillin (with or without clavulanate) against three or four doses a day. Clinical cure at the end of therapy was essentially the same between groups, and side effects such as diarrhea and rash were similar.

This evidence is part of why twice-daily schedules are now standard for most children. It does not mean you can switch your own schedule. If your bottle says every 8 hours, the total daily dose was calculated for that rhythm, so ask your prescriber before changing anything.

Shorter courses: where they work and where they don’t

Every extra day of antibiotics adds side-effect risk and pressure toward resistance. So a big research question has been: how short can a course be without losing effectiveness? The answer depends on the infection and the child’s age.

Pneumonia in young children: SCOUT-CAP. This US trial (Williams and colleagues, JAMA Pediatrics, 2022) enrolled 380 children aged 6 months to 5 years with non-severe pneumonia treated as outpatients. All were already improving on high-dose amoxicillin, amoxicillin-clavulanate, or cefdinir. On day 6, half kept taking the antibiotic for 5 more days, while the other half got a placebo. Inadequate clinical response was under 2% in both groups. Using a ranking that rewarded good outcomes with less drug exposure, the 5-day course came out ahead. Children on the shorter course also carried fewer antibiotic resistance genes in their gut bacteria.

Pneumonia: CAP-IT. The same CAP-IT trial described above also compared 3 days with 7 days of amoxicillin. Retreatment rates were 12.5% in both groups. The one notable difference was cough: it lasted a median of 12 days with the 3-day course and 10 days with the 7-day course.

Ear infections in babies and toddlers: Hoberman 2016. Shorter was not better here. In a trial published in the New England Journal of Medicine, Hoberman and colleagues randomized 520 children aged 6 to 23 months with ear infections to 10 days of amoxicillin-clavulanate, or 5 days followed by 5 days of placebo. Clinical failure occurred in 34% of the 5-day group versus 16% of the 10-day group. The shorter course also did not reduce side effects or resistance. Note that this study used amoxicillin-clavulanate, not plain amoxicillin, but it shaped how doctors think about course length in very young children. If you are unsure how the two drugs differ, see our comparison of amoxicillin vs Augmentin.

These findings line up with current ear infection guidance summarized by the American Academy of Family Physicians: a 10-day course for children under 2 or with severe symptoms, and 5 to 7 days for older children with milder illness. Course length is a prescriber’s call based on age, severity, and response, so finish the course you were given unless your clinician tells you otherwise.

Once-daily amoxicillin for strep throat

Strep throat is one infection where a single daily dose has solid support. A randomized trial by Clegg and colleagues (Pediatric Infectious Disease Journal, 2006) enrolled 652 patients aged 3 to 18. They received 10 days of either once-daily amoxicillin (750 mg or 1,000 mg depending on weight) or twice-daily amoxicillin at the same daily total. Once-daily dosing met the trial’s noninferiority test, and side effects were comparable.

The IDSA 2012 guideline cites this kind of evidence when it lists once-daily amoxicillin as a strongly recommended option. The guideline also points out that a single daily dose may make it easier to finish all 10 days, and that amoxicillin is inexpensive and tastes better than penicillin V liquid.

Taking amoxicillin correctly: practical questions

Getting each dose in on time matters as much as the amoxicillin dosage on the label. These are the questions pharmacists hear most often.

If you miss a dose

MedlinePlus, from the US National Library of Medicine, advises taking a missed dose as soon as you remember. If it is almost time for the next one, skip the missed dose and carry on with your usual schedule. Do not take a double dose to make up for it.

If you miss doses often, tell your prescriber. A once- or twice-daily schedule may be an option, and a phone alarm can help.

With or without food

Amoxicillin can be taken with or without food. The FDA label suggests taking it at the start of a meal to lower the chance of stomach upset. Spacing doses evenly through the day, such as roughly every 12 hours for a twice-daily schedule, helps keep drug levels steady.

Mild nausea or loose stools are common. Our guide to amoxicillin side effects explains which symptoms are expected and which need a call to your doctor.

Measuring liquid amoxicillin

• Shake the bottle well before every dose so the medicine is evenly mixed.
• Use an oral syringe or dosing cup marked in mL. Kitchen teaspoons vary widely in size and are not accurate enough for weight-based doses. Your pharmacy can give you a syringe at no or low cost.
• Check the decimal. 5.6 mL and 56 mL look similar on a hastily read label. If an amount seems large, ask before giving it.
• Squirt slowly toward the inside of the cheek, not the back of the throat, to reduce gagging and spitting.

Storing the suspension

Pharmacies mix the powder with water when you pick it up. After that, the FDA label and MedlinePlus agree on a few points:

• Refrigeration is preferred, but room temperature is acceptable. Do not freeze it.
• Keep the bottle tightly closed and out of children’s reach.
• Throw away any unused liquid after 14 days. Do not save it for a future illness.

Leftover medicine is a sign that doses were missed or the course was cut short. It is also tempting to reuse later, which is risky: the next illness may be viral, may need a different drug, or may need a different dose based on new weight.

What an overdose looks like

Accidental extra doses happen, especially with sweet-tasting children’s liquid. The FDA label notes that in one study of 51 children, overdoses under 250 mg/kg were not linked to significant symptoms. Larger overdoses can strain the kidneys. The label describes kidney inflammation and crystals in the urine in some cases, and MedlinePlus lists cloudy or bloody urine and decreased urination as warning signs.

If you think someone took too much, call Poison Control at 1-800-222-1222 right away, even if they seem fine. If the person has collapsed, had a seizure, has trouble breathing, or cannot be woken, call 911.

An overdose is different from an allergic reaction. Hives, swelling, or wheezing after even a normal dose point to allergy, which our amoxicillin allergy guide covers in detail.

Amoxicillin dosage myths vs facts

Myth	Fact
“Stop when you feel better.”	Feeling better often comes before the infection is fully cleared. Course length is chosen by your prescriber. Stopping early without advice can lead to relapse, and for strep throat the label calls for at least 10 days.
“More milligrams means a faster cure.”	Amoxicillin works best when levels stay above a threshold for enough time, not from a single big spike. Extra doses add side-effect risk, and the CAP-IT trial found lower and higher doses performed similarly for childhood pneumonia.
“My child’s dose looks too high, so the pharmacy made a mistake.”	Guideline doses of 80 to 90 mg/kg/day for ear infections and pneumonia are about double the older label figures. A high dose is often intentional, but always ask if you are unsure.
“A teaspoon is the same as 5 mL.”	Household spoons vary widely. Use the oral syringe or cup from the pharmacy.
“Leftover amoxicillin is fine for the next infection.”	Mixed suspension should be discarded after 14 days, the next illness may not need an antibiotic, and the right dose may have changed.
“If I miss a dose, I should double the next one.”	Do not double up. Take it when you remember, or skip it if the next dose is nearly due.

Frequently asked questions

What is the usual amoxicillin dosage for adults?

Under the FDA label, adults typically take 500 mg or 875 mg every 12 hours, or 250 mg or 500 mg every 8 hours, depending on the infection and its severity. The total daily range on the label is 750 to 1,750 mg. Your prescription may differ for specific conditions like H. pylori or for kidney problems.

Why is my child’s amoxicillin dose higher than the label?

For ear infections and pneumonia, AAP and PIDS/IDSA guidelines recommend about 80 to 90 mg/kg/day, roughly double the older label figures. The higher dose helps reach pneumococcal strains that are less sensitive to penicillin. If the number still seems wrong, ask your pharmacist to double-check.

Is 875 mg stronger than 500 mg?

Each 875 mg tablet contains more drug, but the two are used on different schedules. 875 mg twice daily (1,750 mg a day) and 500 mg three times daily (1,500 mg a day) are close in total. The label says people with a GFR below 30 mL/min should not take the 875 mg dose.

How long does a course of amoxicillin last?

It depends on the infection and age. Strep throat is usually 10 days, ear infections in children under 2 typically run 10 days, and recent trials support 5 days or fewer for uncomplicated pneumonia in young children who are improving. Follow the length your prescriber chose.

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Medical disclaimer: This article is for general education and summarizes published prescribing information and research. It does not replace advice from a doctor, pharmacist, or other qualified clinician, and it should not be used to choose, start, change, or stop any medicine. Always follow the instructions on your own prescription, and never use leftover or someone else’s antibiotics. If you think you or your child is having a serious reaction or has taken too much, call 911 or Poison Control at 1-800-222-1222.

References

1. US Food and Drug Administration. Amoxicillin capsules, tablets, and for oral suspension: prescribing information (FDALabel; Dosage and Administration revised August 2025).
2. MedlinePlus, US National Library of Medicine. Amoxicillin drug information (revised May 2026).
3. Lieberthal AS, et al. The diagnosis and management of acute otitis media. American Academy of Pediatrics clinical practice guideline. Pediatrics. 2013;131(3):e964-e999.
4. American Academy of Family Physicians. Otitis media: rapid evidence review. Am Fam Physician. 2019.
5. Bradley JS, et al. Executive summary: management of community-acquired pneumonia in infants and children older than 3 months of age (PIDS/IDSA guideline). Clin Infect Dis. 2011;53(7):617-630.
6. Shulman ST, et al. Clinical practice guideline for the diagnosis and management of group A streptococcal pharyngitis: 2012 update by the IDSA. Clin Infect Dis. 2012;55(10):e86-e102.
7. Bielicki JA, et al. Effect of amoxicillin dose and treatment duration on the need for antibiotic re-treatment in children with community-acquired pneumonia: the CAP-IT randomized clinical trial. JAMA. 2021;326(17):1713-1724.
8. Williams DJ, Creech CB, et al. Short- vs standard-course outpatient antibiotic therapy for community-acquired pneumonia in children: the SCOUT-CAP randomized clinical trial. JAMA Pediatr. 2022;176(3).
9. Hoberman A, et al. Shortened antimicrobial treatment for acute otitis media in young children. N Engl J Med. 2016;375(25):2446-2456.
10. Thanaviratananich S, et al. Once or twice daily versus three times daily amoxicillin with or without clavulanate for acute otitis media. Cochrane Database Syst Rev. 2013.
11. Clegg HW, et al. Treatment of streptococcal pharyngitis with once-daily compared with twice-daily amoxicillin: a noninferiority trial. Pediatr Infect Dis J. 2006;25(9):761-767.