Amoxicillin is a chemically modified version of naturally occurring antibiotic penicillin, derived from Penicillium mold. Compared to penicillin, advantages of amoxicillin include better absorption from the digestive system and effectiveness against a broader range of bacteria. Taken by mouth, amoxicillin can be used in children to treat various bacterial infections, including middle ear infections, strep throat and pneumonia. When prescribed for children, amoxicillin dosage depends on the condition being treated and the child's age or weight. Individual circumstances vary, so follow your doctor's dosage instructions.
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Infants Up to 3 Months
The body metabolizes and eliminates medications by different pathways. Amoxicillin is primarily eliminated from the body through the urine, after being filtered from the blood by the kidneys. Because newborns and young infants up to 3 months of age may not have fully developed kidney function, the recommended dosage of amoxicillin is no more than 30 milligrams per kilogram per day (mg/kg/d), divided in 2 doses to be given every 12 hours. Your doctor will calculate the appropriate amount of amoxicillin liquid for your infant based on this dosage recommendation, and the site and severity of the infection.
Children Older Than 3 Months Weighing Up To 88 Pounds
Antibiotics like amoxicillin must reach a certain concentration in the body to kill bacteria. For this reason, the dosage of amoxicillin in children older than 3 months weighing up to 88 pounds is based on body weight. The larger a child is, the higher the dosage of amoxicillin needed to achieve an effective concentration of the antibiotic in the body.
When amoxicillin is given twice daily, every 12 hours, the recommended dosage for children older than 3 months weighing up to 88 pounds is 25 to 45 mg/kg/d. When amoxicillin is given 3 times daily, every 8 hours, the recommended dosage is 20 to 40 mg/kg/d. The lower end of the dosage range is typically used for milder infections, and the higher dosage reserved for more severe infections. The site of the infection is also a consideration in determining the specific amoxicillin dosage.
Children Weighing More Than 88 Pounds
Amoxicillin dosages for children and adolescents weighing more than 88 pounds is generally the same as for adults, and is not based on body weight. The recommended amoxicillin dosage for these older children and adults is 500 to 875 mg every 12 hours, or 250 to 500 mg every 8 hours. As with younger children, the exact dosage prescribed depends on the site and severity of the infection.
Successful treatment of a bacterial infection with amoxicillin or another antibiotic depends not only on the appropriate dosage, but also taking the medicine as recommended each day for the full duration prescribed. Although it may be tempting to stop the antibiotic once your child feels better, doing so could result in a relapse. Additionally, a partially treated infection could lead to the bacteria developing resistance to amoxicillin. This could make the relapse more difficult to treat effectively. Call you doctor if you have any questions about your child's amoxicillin prescription or how to administer it.
Reviewed and revised by: Tina M. St. John, M.D.