Amoxicillin Side Effects

Some side effects of amoxicillin may not be reported. Always consult your doctor or healthcare specialist for medical advice. You may also report side effects to the FDA.

For the Consumer

Applies to amoxicillin: for suspension oral, oral capsule, oral powder for reconstitution, oral tablet, oral tablet chewable, oral tablet extended release

Get emergency medical help if you have any of these signs of an allergic reaction while taking amoxicillin: hives; difficulty breathing; swelling of your face, lips, tongue, or throat.

Call your doctor at once if you have a serious side effect such as:

• white patches or sores inside your mouth or on your lips;

• fever, swollen glands, rash or itching, joint pain, or general ill feeling;

• pale or yellowed skin, yellowing of the eyes, dark colored urine, fever, confusion or weakness;

• severe tingling, numbness, pain, muscle weakness;

• easy bruising, unusual bleeding (nose, mouth, vagina, or rectum), purple or red pinpoint spots under your skin; or

• severe skin reaction -- fever, sore throat, swelling in your face or tongue, burning in your eyes, skin pain, followed by a red or purple skin rash that spreads (especially in the face or upper body) and causes blistering and peeling.

Less serious side effects of amoxicillin may include:

• stomach pain, nausea, vomiting;

• vaginal itching or discharge;

• headache; or

• swollen, black, or "hairy" tongue.

This is not a complete list of side effects and others may occur. Call your doctor for medical advice about side effects.

For Healthcare Professionals

Applies to amoxicillin: oral capsule, oral powder for reconstitution, oral tablet, oral tablet chewable, oral tablet dispersible, oral tablet extended release

Hypersensitivity

Hypersensitivity reactions are more likely in patients with a history of allergy, asthma, hay fever, or urticaria.

Hypersensitivity reactions have been reported in up to 10% of patients and have included anaphylaxis, urticarial rash, erythematous maculopapular rash, serum sickness-like reactions, erythema multiforme, urticaria, edema, hypotension, fever, eosinophilia, exfoliative dermatitis, toxic epidermal necrolysis, acute generalized exanthematous pustulosis, hypersensitivity vasculitis, angioedema, Stevens-Johnson syndrome, and dyspnea.

Dermatologic

Dermatologic side effects have included rash, fixed drug eruption, and bullous pemphigoid. Erythematous maculopapular rashes occur frequently in patients with infectious mononucleosis who take amoxicillin; these may be due to hypersensitivity.

Three out of four patients with infectious mononucleosis and an amoxicillin-associated rash displayed hypersensitivity to amoxicillin and ampicillin by skin tests and lymphocyte transformation tests. Two of these patients had side-chain-specific sensitization.

Gastrointestinal

Gastrointestinal side effects have included diarrhea, nausea, vomiting, generalized abdominal cramps, colitis, hemorrhagic colitis, pseudomembranous colitis (Clostridium difficile associated diarrhea), and black hairy tongue. Abdominal pain has also been reported.

Amoxicillin has been associated with hemorrhagic, sometimes inflammatory colitis, which typically affects the ascending colon. Clostridium difficile pseudomembranous colitis has been reported.

Renal

Renal side effects have included crystalluria and acute interstitial nephritis, often associated with fever, rash and eosinophilia.

Hematologic

A patient undergoing dental extraction and receiving warfarin anticoagulation therapy had prolonged bleeding times (PT and INR), and decreased hemoglobin and hematocrit. The bleeding was felt due to vitamin K deficiency as a result of depletion of intrinsic vitamin K-producing gut flora from use of amoxicillin for prophylaxis of subacute bacterial endocarditis.

Hematologic side effects associated with penicillins have included thrombocytopenia, anemia, leukopenia, thrombocytopenic purpura, agranulocytosis, hemolytic anemia, eosinophilia, and granulocytopenia. These effects are usually reversible and are believed to be due to hypersensitivity reactions.

Immunologic

Immunologic side effects have included mucocutaneous candidiasis and vulvovaginal mycotic infection.

Nervous system

Nervous system side effects have rarely included headache, somnolence, dizziness, reversible hyperactivity, agitation, anxiety, insomnia, confusion, convulsions, behavioral changes, and aseptic meningitis. Rare cases of psychosis associated with amoxicillin therapy have been reported but may have been due to underlying infection or concomitant medication.

Hepatic

Hepatic side effects have included moderate elevations of AST (SGOT) and/or ALT (SGPT) levels, cholestatic jaundice, hepatic cholestasis, and acute cytolytic hepatitis.

Other

Other side effects have rarely included brown, yellow, or gray tooth discoloration, primarily in pediatric patients. Brushing or dental cleaning reduced or eliminated the discoloration in most cases.

Respiratory

Respiratory side effects have included cough and rhinorrhea.

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