Effects of Amoxicillin

Amoxicillin is a penicillin-derived antibiotic drug that was approved in 1974 by the U.S. Food and Drug Administration to fight bacterial infections, according to Drugs.com. Amoxicillin is an active ingredient in both generic and brand-name antibiotic formulations that include tablets; capsules; eye, ear and skin ointments; oral suspensions; and intravenous preparations. Like any antibiotic, amoxicillin can save lives as well as cause harmful effects.

Beneficial Effects of Amoxicillin

DailyMed.com notes that amoxicillin is employed to combat many types of bacterial infections, including those of the eyes, ears, mouth, throat, bladder, lungs, skin and sexual organs. Specifically, amoxicillin has shown effectiveness against Staphylococcus strains, Streptococcus strains, Escherichia coli, Haemophilus influenzae, Neisseria gonorrhoeae and Helicobacter pylori.

Amoxicillin in combination with clarithromycin and lansoprazole, known as "triple therapy," is especially effective against the Helicobacter pylori bacteria, which have been implicated in stomach infections that lead to ulcerations, as cited on DailyMed.com. Clarithromycin is another antibiotic, while lansoprazole reduces stomach acidity. Elimination of Helicobacter pylori has proven to reduce the risk of both stomach and duodenal ulcers.

Potential Allergic Reactions to Amoxicillin

The most serious negative side effect from taking amoxicillin is a life-threatening allergic response, often referred to as an anaphylactic reaction. The "Compendium of Pharmaceuticals and Specialties" cites that hypersensitivity responses have been observed in up to 10 percent of patients studied in controlled trials on amoxicillin. Specifically, the most common responses were anaphylaxis, dyspnea, asthma attacks, urticaria of the skin, hives, dermatitis, edema of the skin, vasculitis, increased body temperature and decreased blood pressure.

Although rare, amoxicillin use can cause Stevens-Johnson syndrome, which involves separation of the epidermis from the dermis due to skin cell death. Stevens-Johnson syndrome is painful and can lead to widespread infection and death.

Negative Gastrointestinal Effects of Amoxicillin

Like any antibiotic, the most common negative effects from amoxicillin involve the gastrointestinal system. RxList.com notes that diarrhea and nausea, frequently leading to vomiting, were the most commonly reported gastrointestinal effects caused by all amoxicillin formulations. Less common reported gastrointestinal symptoms included abdominal cramping, abdominal colitis, pseudo-membranous colitis and gross bleeding related to colitis.

RxList also adds that in clinical trials involving amoxicillin as part of the "triple therapy" approach to combating Helicobacter pylori infection, the most common reported negative effects were diarrhea in 7 percent of those studied, headache in 6 percent of those studied and disrupted taste perception in 5 percent of those studied.

Candidiasis From Amoxicillin Use

Candidiasis is defined as an internal yeast infection caused by an overgrowth of fungus, usually Candida albicans. Misusing or overusing penicillin-related antibiotics, such as amoxicillin, is a common cause of candidiasis. Candida albicans infections often manifest in the mucous membranes of the vaginal walls, mouth and lower intestines, causing itching, inflammatory pain and white yeast discharge, known as "Candida thrush." A study that appeared in a 2005 edition of "Intensive Care Medicine" concluded that broad-spectrum antibiotic use does lead to multisite infections of Candida species.