Amoxicillin is an antibiotic that can be used to treat many common infections such as pneumonia, gonorrhea, bronchitis, infections of the ear, nose, and throat. It is also used in combination with other antibiotics to eliminate H. Pylori, which causes chronic gastritis and ulcers.
It is a beta-lactam antibiotic just like Penicillin, but is used more often than penicillin because it is more easily absorbed and comes in a variety of preparations. As a beta-lactam antibiotic it is useless against beta-lactamase secreting bacteria. In addition, if an allergy is known to be present for Penicillin, then it will most likely be present for Amoxicillin as well.
Mode of Action

Like other beta-lactam antibiotic, Amoxicillin acts against bacteria by attacking its cell wall. More specifically, it inhibits "cross-linking" between peptidoglycan polymers. Peptidoglyan polymers are proteins that are the building blocks of the cell membranes of bacteria. They make up the majority of gram-positive bacterial cell wall and part of the inner membrane of gram-negative bacteria. It is useful in destroying both kinds of bacteria.
Mode of Administration
Amoxicillin is flexible in its mode of administration. It can be taken via capsule, chewable in a variety of flavors, and as a liquid slurry that can be mixed with syrup for pediatric administration. This is precisely the reason why Amoxicillin is one of the most commonly prescribed antibiotics for children. Amoxicillin can also be administered intravenously.

Side Effects of Amoxicillin
Side effects of Amoxicillin include nausea, vomiting, and diarrhea. A more dangerous side effect can be due to Type-I Hypersensitivity Allergic Reaction. An onset of acute rash, hives, swelling of the tongue, swelling of the face, dark urine, jaundice, and itching could be a sign of a severe allergic reaction and should be treated immediately as such a reaction can be life-threatening if edema of the larynx obstructs the airway, and diminishes the ability to breathe.
Some Amoxicillin Susceptible Organisms
Aerobic Gram-Positive Microorganisms:


Enterococcus faecalis
Staphylococcus spp.
Streptococcus pneumonia
Streptococcus spp.
Aerobic Gram-Negative Microorganisms:
Escherichia coli
Haemophilus influenzae
Neisseria gonorrhoeae
Proteus mirabilis
Helicobacter pylori

Thanks Yana G. Yevstegneeva, 2nd-year Medical Student.