by Dr. Manura Nanayakkara

Created on: May 07, 2010   Last Updated: January 13, 2011

Amoxicillin is a common prescription only broad spectrum antibiotic in the penicillin group. This medication is quite effective and has low side effects profile. Amoxicillin acts by inhibiting bacterial cell wall synthesis.

This medication is available as capsules, tablets, suspension form for children, and injection form. Oral Amoxicillin should be taken as whole with a full glass of water to minimize side effects. In addition, taking this medication with food reduces gastric side effects.  Some doctors prescribe antacids with Amoxicillin to reduce gastric side effects. Before prescribing Amoxicillin, your doctor should know whether you have kidney problems, liver problems, fever with red rashes, gout, leukemia or allergies to the penicillin group of antibiotics.

*Common side effects*

 One of the most common side effects reported with Amoxicillin are gastro intestinal effects (nausea vomiting and diarrhea). Usually it is not a problem to most of the patients. Some patients are allergic to beta lactam antibiotics. These patients can develop allergic rashes to Amoxicillin. Certain patients can get edema in lips tongue and skin (hives) as well.

*Serious complications*

 Very rarely patients can develop another life threatening complication called anaphylactic reaction (shock). This is characterized by sudden faintish ness, low blood pressure, and pallor. In an anaphylactic reaction, drug should be discontinued immediately, and patient should seek emergency medical help. Rarely some patients have reported skin peeling off from the body and erythema multiforme.

Rarely patients can develop a condition called antibiotic associated colitis. This is common to most of the broad spectrum antibiotics. It is characterized by severe foul smelling diarrhea with gross blood and mucus, and abdominal cramps. Antibiotic associated colitis is caused by toxins released by a bacteria called clostridium difficile. It is a bacterium in normal intestinal flora. Broad spectrum antibiotics like Amoxicillin disrupt normal intestinal flora and allow overgrowth of bugs like clostridium difficile.

*Amoxicillin Rash* 

Some patients can develop rashes, even without an allergic history to Penicillin antibiotics. These are sometimes called Amoxicillin rashes. It is a rash with a red patch and a skin elevation. This appears usually 3-14 days after initiation of therapy. It usually begins on trunk, and spreads out to involve most of the body. In most patients’ rash subsides in 6 – 14 days even with the drug. It will settle usually in seven days once the drug is discontinued.  Incidence of Amoxicillin rash is higher with several viral infections. It is especially common in Infectious Mononucleosis Infection (Glandular fever), and in lymphatic leukemia. Increased incidence of rash is also reported in patients who are taking both Amoxicillin and Allopurinol for gout.

*Other side effects*

Very rarely patients can develop convulsions due to CNS toxicity. Especially in high doses with renal impairment. Doctors will reduce the dose, if you have renal impairment. Reduced effectiveness of Oral Contraceptive Pill is a debatable drug interaction. It is usually consider as a safe Drug in pregnancy and lactation.

Sources

British National Formulary 58th edition. www.bnf.org

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