[9][18] Children with acute otitis media who are younger than six months of age are generally treated with amoxicillin or other antibiotics.

[22] Amoxicillin is considered the first-line empirical treatment for most cases of uncomplicated bacterial sinusitis in children and adults when culture data is unavailable.

[23][24][25] Amoxicillin is recommended as the preferred first-line treatment for community-acquired pneumonia in adults by the National Institute for Health and Care Excellence, either alone (mild to moderate severity disease) or in combination with a macrolide.

[26] Research suggests that is as effective as co-amoxiclav (a broad-spectrum antibiotic) for people admitted to hospital with pneumonia, regardless of its severity.

[34] Amoxicillin is recommended by the World Health Organization for the treatment of infants with signs and symptoms of pneumonia in resource-limited situations when the parents are unable or unwilling to accept hospitalization of the child.

Amoxicillin in combination with gentamicin is recommended for the treatment of infants with signs of other severe infections when hospitalization is not an option.

[38] It is a moderate-spectrum, bacteriolytic, β-lactam antibiotic in the aminopenicillin family used to treat susceptible Gram-positive and Gram-negative bacteria.

In general, Streptococcus, Bacillus subtilis, Enterococcus, Haemophilus, Helicobacter, and Moraxella are susceptible to amoxicillin, whereas Citrobacter, Klebsiella and Pseudomonas aeruginosa are resistant to it.

[39] Some E. coli and most clinical strains of Staphylococcus aureus have developed resistance to amoxicillin to varying degrees.

[40] Adverse effects are similar to those for other β-lactam antibiotics, including nausea, vomiting, rashes, and antibiotic-associated colitis.

Rarer adverse effects include mental and behavioral changes, lightheadedness, insomnia, hyperactivity, agitation, confusion, anxiety, sensitivity to lights and sounds, and unclear thinking.

[45] The onset of an allergic reaction to amoxicillin can be very sudden and intense; emergency medical attention must be sought as quickly as possible.

The initial phase of such a reaction often starts with a change in mental state, skin rash with intense itching (often beginning in the fingertips and around the groin area and rapidly spreading), and sensations of fever, nausea, and vomiting.

Young children having ingested acute overdoses of amoxicillin manifested lethargy, vomiting, and renal dysfunction.

For this reason, the severity and frequency of adverse effects from amoxicillin are probably higher than reported in clinical trials.

This rash is unlikely to be a true allergic reaction and is not a contraindication for future amoxicillin usage, nor should the current regimen necessarily be stopped.

Some studies indicate about 80–90% of patients with acute Epstein–Barr virus infection treated with amoxicillin or ampicillin develop such a rash.

[59] It inhibits cross-linkage between the linear peptidoglycan polymer chains that make up a major component of the bacterial cell wall.

It was invented by Anthony Alfred Walter Long and John Herbert Charles Nayler, two British scientists.

[citation needed] Amoxicillin is one of the semisynthetic penicillins discovered by the former pharmaceutical company Beecham Group.