Adverse effects

Adverse effects are similar to those for other β-lactam antibiotics, including nausea, vomiting, rashes, and antibiotic-associated colitis. Loose bowel movements (diarrhea) may also occur. Rarer adverse effects include mental changes, lightheadedness, insomnia, confusion, anxiety, sensitivity to lights and sounds, and unclear thinking. Immediate medical care is required upon the first signs of these adverse effects.[citation needed]

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 fingertips and around groin area and rapidly spreading), and sensations of fever, nausea, and vomiting. Any other symptoms that seem even remotely suspicious must be taken very seriously. However, more mild allergy symptoms, such as a rash, can occur at any time during treatment, even up to a week after treatment has ceased. For some people allergic to amoxicillin, the adverse effects can be fatal due to anaphylaxis.

Use of the amoxicillin/clavulanic acid combination for more than one week has caused mild hepatitis in some patients. Young children having ingested acute overdoses of amoxicillin manifested lethargy, vomiting, and renal dysfunction.[28][29]

There is poor reporting of adverse effects of amoxicillin from clinical trials. For this reason, the severity and frequency of adverse effects from amoxicillin is probably higher than reported from clinical trials.[30]

Nonallergic rash[edit]

Between 3 and 10% of children taking amoxicillin (or ampicillin) show a late-developing (>72 hours after beginning medication and having never taken penicillin-like medication previously) rash, which is sometimes referred to as the “amoxicillin rash”. The rash can also occur in adults.

The rash is described as maculopapular or morbilliform (measles-like; therefore, in medical literature, it is called “amoxicillin-induced morbilliform rash”.[31]). It starts on the trunk and can spread from there. 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. However, this common amoxicillin rash and a dangerous allergic reaction cannot easily be distinguished by inexperienced persons, so a healthcare professional is often required to distinguish between the two.[32][33]

A nonallergic amoxicillin rash may also be an indicator of infectious mononucleosis. Some studies indicate about 80-90% of patients with acute Epstein Barr virus infection treated with amoxicillin or ampicillin develop such a rash.[34]

Interactions[edit]

Amoxicillin may interact with these drugs:

Pharmacology[edit]

Amoxicillin (α-amino-p-hydroxybenzyl penicillin) is a semisynthetic derivative of penicillin with a structure similar to ampicillin but with better absorption when taken by mouth, thus yielding higher concentrations in blood and in urine.[37] Amoxicillin diffuses easily into tissues and body fluids. Penetration into the central nervous system increases in meningitis. It will cross the placenta and is excreted into breastmilk in small quantities. It is excreted into the urine and metabolized by the liver. It has an onset of 30 minutes and a half-life of 3.7 hours in newborns and 1.4 hours in adults.[12]

Amoxicillin attaches to the cell wall of susceptible bacteria and results in their death. It also is a bactericidal compound. It is effective against streptococci, pneumococci, enterococci, Haemophilus influenzaeEscherichia coliProteus mirabilisNeisseria meningitidisNeisseria gonorrhoeaeShigellaChlamydia trachomatisSalmonellaBorrelia burgdorferi, and Helicobacter pylori.[12] As a derivative of ampicillin, amoxicillin is a member of the penicillin family and, like penicillins, is a β-lactam antibiotic.[38] It inhibits cross-linkage between the linear peptidoglycan polymer chains that make up a major component of the bacterial cell wall. It has two ionizable groups in the physiological range (the amino group in alpha-position to the amide carbonyl group and the carboxyl group).[39]

History[edit]

Amoxicillin was one of several semisynthetic derivatives of 6-aminopenicillanic acid (6-APA) developed at Beecham, England in the 1960s.[40][41] It became available in 1972 and was the second aminopenicillin to reach the market (after ampicillin in 1961).[42][43][44] Co-amoxiclav became available in 1981.[43]