AMX500 mg

Respiratory Tract and ENT Infections

AMX is an established, FDA-approved treatment for infections of the ear, nose, and throat (including acute otitis media, sinusitis, tonsillitis, and pharyngitis) and for lower respiratory tract infections such as bacterial bronchitis and community-acquired pneumonia caused by susceptible, non-beta-lactamase-producing organisms including Streptococcus pneumoniae, Haemophilus influenzae (non-beta-lactamase-producing strains), and Streptococcus pyogenes.

Genitourinary Tract Infections

AMX is established therapy for uncomplicated urinary tract infections caused by susceptible E. coli, Proteus mirabilis, and enterococci, and, at high single-dose regimens combined with probenecid, for uncomplicated gonorrhea (where locally supported by susceptibility data; ceftriaxone-based regimens are now preferred first-line therapy in most current guidelines because of resistance).

Skin and Soft Tissue Infections

AMX is an established treatment for skin and skin-structure infections caused by susceptible, non-beta-lactamase-producing staphylococci and streptococci.

Helicobacter pylori Eradication

AMX is guideline-supported therapy for H. pylori eradication in peptic ulcer disease, but only as part of combination regimens with a proton pump inhibitor and clarithromycin (triple therapy) or with a proton pump inhibitor alone at higher, more frequent dosing (dual therapy); AMX is never used alone for this indication because monotherapy does not reliably eradicate H. pylori and promotes resistance.

Dental Infections

AMX is commonly used, and supported by dental practice guidance, as short-term therapy for odontogenic (dental) infections and as antibiotic prophylaxis before certain dental procedures in patients at high risk of infective endocarditis, per American Heart Association guidance.

Anthrax Post-Exposure Prophylaxis and Treatment (Adjunct/Alternative Use)

AMX is a CDC-recognized alternative agent for post-exposure prophylaxis following confirmed susceptible Bacillus anthracis exposure, and for continuation therapy after initial treatment, used under public-health or specialist direction rather than as routine outpatient therapy.

Each tablet or capsule contains Amoxicillin Trihydrate equivalent to 250 mg or 500 mg of amoxicillin. Chewable tablets and oral suspension (powder for reconstitution) formulations of Amoxicillin Trihydrate are also available, commonly providing 125 mg or 250 mg of amoxicillin per 5 mL after reconstitution. Exact strengths and available dosage forms vary by manufacturer.

AMX is a semi-synthetic, moderate-spectrum, beta-lactam antibiotic of the aminopenicillin subclass. AMX is bactericidal, acting by inhibiting bacterial cell-wall synthesis, and is active against a range of susceptible gram-positive and gram-negative organisms that do not produce beta-lactamase enzymes. AMX is chemically and pharmacologically related to ampicillin but is better absorbed after oral administration, allowing less frequent dosing. AMX is widely used for common bacterial infections of the respiratory tract, ears, urinary tract, skin, and, in combination regimens, for Helicobacter pylori eradication. AMX does not treat infections caused by viruses, such as the common cold or influenza, and should be taken exactly as prescribed by a qualified healthcare professional.

Antibiotic — Aminopenicillin (beta-lactam antibiotic class)

Amoxicillin Trihydrate is a bactericidal antibiotic that inhibits the biosynthesis of bacterial cell-wall mucopeptide by binding to penicillin-binding proteins (PBPs) located inside the bacterial cell wall, which interferes with cross-linking of the peptidoglycan layer. This weakens the cell wall, ultimately causing bacterial cell lysis and death.

Amoxicillin Trihydrate is stable in gastric acid and is well and rapidly absorbed after oral administration, largely independent of food intake, with peak plasma concentrations typically reached within 1 to 2 hours of dosing. Amoxicillin Trihydrate is widely distributed into most body tissues and fluids, with relatively low plasma protein binding (approximately 20%). Only a small proportion of Amoxicillin Trihydrate is metabolized; the majority is excreted unchanged in the urine via renal tubular secretion and glomerular filtration, giving Amoxicillin Trihydrate a short elimination half-life of approximately 1 to 1.5 hours in patients with normal renal function. Renal impairment prolongs the half-life of Amoxicillin Trihydrate and requires dose-interval adjustment.

• AMX may be taken with or without food; taking it with food can reduce stomach upset without significantly affecting absorption.
• Swallow tablets/capsules of AMX whole with a full glass of water. Chewable tablets of AMX should be chewed or crushed before swallowing, as directed on the label.
• Oral suspension of AMX should be shaken well before each dose and measured using an accurate oral dosing syringe or cup, not a household spoon.
• Space doses of AMX evenly throughout the day (e.g., every 8 or every 12 hours) to maintain effective blood levels, as directed by the prescriber.
• Take AMX exactly as prescribed by your physician; do not stop, extend, skip doses, or share this medicine with others without medical advice, and complete the full prescribed course even if symptoms improve early.

• Probenecid: decreases renal tubular secretion of AMX, increasing and prolonging its blood levels; this combination is sometimes used intentionally (e.g., in gonorrhea treatment) but requires awareness of increased amoxicillin exposure.
• Allopurinol: concurrent use with AMX has been associated with a higher incidence of skin rash, particularly in patients also receiving allopurinol for hyperuricemia; the exact mechanism is unclear.
• Oral anticoagulants (e.g., warfarin): AMX may prolong prothrombin time/INR in some patients, increasing bleeding risk; more frequent INR monitoring is advised when starting or stopping AMX in patients on anticoagulant therapy.
• Combined hormonal contraceptives: AMX, like other antibiotics that alter gut flora, has been reported rarely to reduce enterohepatic recirculation of estrogens, potentially lowering contraceptive efficacy; an additional barrier method is often advised as a precaution during treatment.
• Methotrexate: penicillins including AMX may reduce renal clearance of methotrexate, increasing the risk of methotrexate toxicity; concurrent use requires monitoring.
• Other beta-lactam antibiotics or bacteriostatic antibiotics (e.g., tetracyclines, chloramphenicol): bacteriostatic agents may theoretically interfere with the bactericidal action of AMX; concurrent use is generally avoided unless specifically directed.

Common Side Effects

• Diarrhea, nausea, and vomiting
• Indigestion or abdominal discomfort
• Skin rash (including a common, non-allergic, maculopapular rash that can occur when AMX is given to patients with underlying infectious mononucleosis — see Precautions and Warnings)
• Headache

Serious Side Effects (Seek Medical Attention)

• Signs of a severe allergic reaction, such as swelling of the face, lips, tongue, or throat, difficulty breathing, or anaphylaxis
• Severe, persistent, or bloody diarrhea, which may indicate Clostridioides difficile-associated diarrhea or colitis, and can occur even weeks after stopping AMX
• Severe skin reactions such as blistering, peeling skin, or widespread rash (possible Stevens-Johnson syndrome, toxic epidermal necrolysis, or DRESS syndrome)
• Yellowing of the skin or eyes, dark urine, or unusual tiredness, which may indicate liver injury (hepatitis or cholestatic jaundice)
• Unusual bruising, bleeding, or signs of a blood disorder
• New or worsening seizures, which have rarely been reported, particularly with high doses or in patients with renal impairment

Pregnancy

AMX is widely considered one of the preferred antibiotics for use in pregnancy when a susceptible bacterial infection requires treatment, based on extensive clinical experience and reproduction studies that have not demonstrated an increased risk of fetal harm. However, as with any medicine in pregnancy, AMX should be used only when clearly needed, and the potential benefit should justify the potential risk to the fetus; use of AMX in pregnancy should always be discussed with and directed by a qualified physician.

Breastfeeding

AMX is excreted into human breast milk in small amounts. AMX is generally considered compatible with breastfeeding by most authorities, but the nursing infant should be monitored for possible effects on gut flora, such as diarrhea, thrush, or, rarely, allergic sensitization/rash. Consult a physician before using AMX while breastfeeding, particularly for prolonged courses.

• Hypersensitivity and anaphylaxis: serious and occasionally fatal hypersensitivity reactions, including anaphylaxis, have been reported with AMX and other penicillins, more often in patients with a history of penicillin allergy, other allergies, or asthma. Discontinue AMX immediately and seek emergency care if signs of a severe allergic reaction occur.
• Clostridioides difficile-associated diarrhea (CDAD): as with nearly all antibiotics, AMX can disturb normal gut flora and permit overgrowth of C. difficile, ranging from mild diarrhea to severe, life-threatening colitis; this should be considered in any patient who develops diarrhea during or after treatment with AMX.
• Rash in infectious mononucleosis: a high proportion of patients with infectious mononucleosis who receive AMX develop a non-allergic, generalized maculopapular skin rash; AMX should generally be avoided in patients with suspected mononucleosis, and this rash should be distinguished from a true penicillin allergy.
• Antibiotic stewardship: take AMX exactly as prescribed by your physician; do not stop, extend, skip doses, or share this medicine with others without medical advice. Using AMX for viral infections (such as the common cold) or not completing the full prescribed course can promote antibiotic-resistant bacteria and reduce the future effectiveness of AMX and other antibiotics.
• Superinfection: prolonged or repeated use of AMX may result in overgrowth of non-susceptible organisms, including fungi; new infections occurring during treatment should be evaluated.
• Renal impairment: in patients with significant renal impairment, the dosing interval of AMX should be adjusted, as reduced clearance can lead to elevated blood levels and increased risk of adverse effects, including seizures at high exposure.
• Not effective against viral infections: AMX treats bacterial infections only and has no effect on viruses such as those causing the common cold or influenza.

Reported effects of AMX overdose include gastrointestinal symptoms such as nausea, vomiting, diarrhea, and abdominal pain, along with disturbances in fluid and electrolyte balance. Crystalluria, which may rarely lead to renal impairment, has been reported with very high doses of AMX, particularly with inadequate fluid intake. In patients with renal impairment or after very high doses, AMX has rarely been associated with seizures.

If an overdose of AMX is suspected, seek immediate medical attention or contact a poison control center right away. Management is supportive; maintaining adequate fluid intake and urine output may help prevent crystalluria. AMX can be removed from the circulation by hemodialysis in cases of severe renal impairment. Do not attempt to manage a suspected overdose at home without professional medical guidance.

Store AMX tablets, capsules, and unreconstituted powder for oral suspension at room temperature (below 30°C/86°F), away from direct light and moisture, in the original container, and out of the reach and sight of children. Once the oral suspension of AMX has been reconstituted with water, it should be stored in a refrigerator (2–8°C), keeping it away from freezing, and any unused portion should be discarded after 14 days. Do not use AMX beyond its expiry date.

Children

AMX is approved for use in infants and children, with dosing based on body weight for those under approximately 40 kg and adult dosing thereafter. Dosing of AMX in neonates and infants up to 3 months of age is more conservative, reflecting immature renal function; see Pediatric Uses below.

Elderly

No specific dose reduction of AMX is required in elderly patients based on age alone, provided renal function is normal. Because renal function commonly declines with age, elderly patients should have renal function assessed, and the dosing interval of AMX adjusted accordingly if impairment is present.

Renal Impairment

Because AMX is eliminated primarily by the kidneys, patients with moderate to severe renal impairment (CrCl below approximately 30 mL/min) require an extended dosing interval of AMX to avoid drug accumulation; consult a nephrology or pharmacy dosing reference for precise adjustment based on the degree of impairment.

Hepatic Impairment

AMX is metabolized only to a limited extent by the liver, and formal dose adjustment for hepatic impairment is not well established; nonetheless, AMX should be used with caution and liver function monitored in patients with significant pre-existing liver disease, as hepatic effects have rarely been reported with penicillins.

Pregnant and Breastfeeding Women

See the Pregnancy and Lactation section above for detailed guidance on the use of AMX in this population.

Powder for oral suspension formulations of AMX must be reconstituted before use. To reconstitute, add the amount of water specified on the manufacturer's label in two portions, shaking well after each addition, to obtain a uniform suspension at the labeled concentration (commonly 125 mg/5 mL or 250 mg/5 mL). Shake the reconstituted suspension of AMX well before each dose. Store the reconstituted suspension in a refrigerator (2–8°C) and discard any unused portion after 14 days. Do not freeze the reconstituted suspension of AMX.

Antibiotics > Beta-lactam antibiotics > Penicillins > Aminopenicillins

Amoxicillin Trihydrate exerts its bactericidal effect by binding to specific penicillin-binding proteins (PBPs) located within the bacterial cell wall. This binding inhibits the transpeptidation (cross-linking) step of peptidoglycan synthesis, which is essential for maintaining bacterial cell-wall structure and integrity. Interference with cell-wall synthesis, combined with continued activation of bacterial autolytic enzymes, leads to lysis and death of actively dividing, susceptible bacteria. Amoxicillin Trihydrate lacks activity against organisms that produce beta-lactamase enzymes, which hydrolyze and inactivate the beta-lactam ring of Amoxicillin Trihydrate before it can act.

B (FDA legacy pregnancy category, as previously assigned prior to the current Pregnancy and Lactation Labeling Rule; see Pregnancy and Lactation section for current, narrative-based guidance)

AMX is approved for use in infants and children for the same categories of susceptible bacterial infections as in adults, with dosing based on body weight (mg/kg/day, divided into 2–3 doses) for children generally weighing less than approximately 40 kg; children at or above this weight are typically dosed using adult regimens of AMX. For acute otitis media, the American Academy of Pediatrics supports a higher-dose regimen of AMX (80–90 mg/kg/day) in areas with significant rates of resistant Streptococcus pneumoniae, to improve the likelihood of achieving effective drug concentrations against less-susceptible strains.

In neonates and infants up to 3 months of age, dosing of AMX is more conservative (maximum 30 mg/kg/day in divided doses every 12 hours) because of immature renal function and reduced drug clearance in this age group; safety and efficacy of specific higher-dose regimens have not been established in this youngest population, and dosing should be directed by a pediatrician or neonatologist. Chewable tablets and oral suspension formulations of AMX are generally preferred for children who cannot swallow tablets or capsules.