Amoxicillin/Clavulanate Side Effects

Please note - some side effects for Amoxicillin/Clavulanate may not be reported. Always consult your doctor or healthcare specialist for medical advice. You may also report side effects to the FDA at http://www.fda.gov/medwatch/ or 1-800-FDA-1088 (1-800-332-1088).

Side Effects of Amoxicillin/Clavulanate - for the consumer

Amoxicillin/Clavulanate

All medicines may cause side effects, but many people have no, or minor side effects. Check with your doctor if any of these most COMMON side effects persist or become bothersome when using Amoxicillin/Clavulanate:

Diarrhea; nausea; vomiting.

Severe allergic reactions (rash; hives; itching; difficulty breathing; tightness in the chest; swelling of the mouth, face, lips, or tongue); bloody stools; confusion; dark urine; fever, chills, or persistent sore throat; red, swollen, blistered, or peeling skin; seizures; severe diarrhea; stomach pain or cramps; unusual bruising or bleeding; vaginal discharge or irritation; yellowing of the skin or eyes.

Amoxicillin/Clavulanate Chewable Tablets

All medicines may cause side effects, but many people have no, or minor side effects. Check with your doctor if any of these most COMMON side effects persist or become bothersome when using Amoxicillin/Clavulanate Chewable Tablets:

Diarrhea; nausea; vomiting.

Severe allergic reactions (rash; hives; itching; difficulty breathing; tightness in the chest; swelling of the mouth, face, lips, or tongue); bloody stools; confusion; dark urine; fever, chills, or persistent sore throat; red, swollen, blistered, or peeling skin; seizures; severe diarrhea; stomach pain or cramps; unusual bruising or bleeding; vaginal discharge or irritation; yellowing of the skin or eyes.

Amoxicillin/Clavulanate Extended-Release Tablets

All medicines may cause side effects, but many people have no, or minor side effects. Check with your doctor if any of these most COMMON side effects persist or become bothersome when using Amoxicillin/Clavulanate Extended-Release Tablets:

Diarrhea; nausea; vomiting.

Severe allergic reactions (rash; hives; itching; difficulty breathing; tightness in the chest; swelling of the mouth, face, lips, or tongue); bloody stools; confusion; dark urine; fever, chills, or persistent sore throat; red, swollen, blistered, or peeling skin; seizures; severe diarrhea; stomach pain or cramps; unusual bruising or bleeding; vaginal discharge or irritation; yellowing of the skin or eyes.

Amoxicillin/Clavulanate Suspension

All medicines may cause side effects, but many people have no, or minor side effects. Check with your doctor if any of these most COMMON side effects persist or become bothersome when using Amoxicillin/Clavulanate Suspension:

Diaper rash; diarrhea; nausea; vomiting.

Severe allergic reactions (rash; hives; itching; difficulty breathing; tightness in the chest; swelling of the mouth, face, lips, or tongue); bloody stools; confusion; dark urine; fever, chills, or persistent sore throat; red, swollen, blistered, or peeling skin; seizures; severe diarrhea; stomach pain or cramps; unusual bruising or bleeding; vaginal discharge or irritation; white patches in the mouth; yellowing of the skin or eyes.

By body system

General side effects

In general, side effects have been classified as mild and transient. Less than 3% of patients in clinical trials discontinued treatment due to side effects. The most frequent adverse reactions associated with immediate-release formulations have included diarrhea/loose stools (9%), nausea (3%), skin rashes and urticaria (3%), vomiting (1%), and vaginitis (1%). Extended-release tablets have been most frequently associated with diarrhea (14.5%), vaginal mycosis (3.3%), nausea (2.1%), and loose stools (1.6%).

Gastrointestinal side effects

Gastrointestinal side effects have included diarrhea, nausea, abdominal pain, vomiting, indigestion, gastritis, generalized abdominal cramps, stomatitis, glossitis, mucocutaneous candidiasis, enterocolitis, black "hairy" tongue, small intestinal motor disturbances, hemorrhagic colitis, and pseudomembranous colitis. Colitis and Clostridium difficile pseudomembranous colitis have been reported with amoxicillin.

Amoxicillin has been associated with hemorrhagic, sometimes inflammatory colitis, which typically affects the ascending colon. In addition, C difficile pseudomembranous colitis should be considered in patients who develop severe or prolonged diarrhea during or following amoxicillin-clavulanate therapy.

The incidence of diarrhea appears to increase with higher doses, and to decrease with twice daily dosing regimens (of immediate release formulations).

Hypersensitivity side effects

Hypersensitivity reactions have occurred in up to 10% of patients, and may present as a skin rash, urticaria, pruritus, angioedema, serum sickness-like reactions (urticaria or skin rash accompanied by arthritis, arthralgia, myalgia, and frequently fever), erythema multiforme, Stevens-Johnson syndrome (rarely), acute generalized exanthematous pustulosis, hypersensitivity vasculitis, exfoliative dermatitis, and toxic epidermal necrolysis. Anaphylaxis has been rarely reported (up to 0.2%). Hypersensitivity may play a role in some cases of amoxicillin-clavulanate-induced renal and hepatic toxicity. Urticarial rash, erythematous maculopapular rash, edema, hypotension, fever, eosinophilia, and dyspnea have been associated with hypersensitivity reactions to amoxicillin.

Dermatologic side effects

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.

Dermatologic side effects have included rash, fixed drug eruption, bullous pemphigoid, erythema multiforme, Stevens-Johnson syndrome, and exfoliative dermatitis. Amoxicillin rashes occur more frequently in patients with unrecognized infectious mononucleosis. This rash is not necessarily indicative of a lifelong amoxicillin hypersensitivity.

Hepatic side effects

Hepatic side effects have included moderate elevations in serum transaminases (ALT and/or AST). Hepatic dysfunction (including cholestatic jaundice and hepatitis, increases in ALT and/or AST, serum bilirubin, and/or alkaline phosphatase) has been reported infrequently. Rare cases of jaundice, ductopenia, cholestatic hepatitis, granulomatous hepatitis, hepatic necrosis, and hepatocellular damage have also been reported. Less than 1 death per approximately 4 million prescriptions has been reported worldwide. Hepatic cholestasis and acute cytolytic hepatitis have been reported with amoxicillin use.

In cases of amoxicillin-clavulanate-induced hepatotoxicity, biopsy findings have typically revealed evidence of cholestatic injury. However, hepatocellular and mixed-type (cholestatic and hepatocellular) injury have also been documented. In many instances, hepatotoxicity may be due to a hypersensitivity. Onset of symptoms has been delayed in some patients, with presentation occurring after therapy has been discontinued. Prolonged treatment may increase the risk of hepatotoxicity. Elderly patients may be at increased risk of developing amoxicillin-clavulanate-induced jaundice. Fatalities are rare, but have been reported.

Rechallenge with amoxicillin alone has not been followed by a recurrence of hepatitis. However, rechallenge with amoxicillin-clavulanate has resulted in a relapse of liver injury. Therefore, the clavulanic acid may be the hepatotoxic part of the drug.

In patients with liver disease, frequent monitoring of liver function tests during amoxicillin-clavulanate therapy is recommended.

Renal side effects

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

A 45-year-old female developed massive crystalluria, gross hematuria, and acute anuric renal failure after 12 days of intravenous amoxicillin-clavulanate at a dose of 2 g amoxicillin 3 times daily (not available in the United States). The crystals were composed of amoxicillin trihydrate. The renal failure and hematuria resolved over 6 days after discontinuation of the antibiotic.

Hematologic side effects

Amoxicillin has been shown to induce hemolytic anemia in rare cases. A case of bone marrow "maturation arrest" resulting in neutropenia and of Henoch-Schonlein purpura syndrome has been associated with amoxicillin-clavulanate.

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, hemolytic anemia, thrombocytopenic purpura, eosinophilia, agranulocytosis, and leukopenia. These are believed to be due to hypersensitivity and are usually reversible when the drug is discontinued. Mild to moderate thrombocytosis has been reported in less than 1% of patients treated with amoxicillin-clavulanate and 3.6% of patients treated with the extended-release tablets. Purpura, pancytopenia, granulocytopenia, medullary aplasia, prolongation of prothrombin time, and transient neutropenia have also been reported.

Immunologic side effects

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

Nervous system side effects

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

Genitourinary side effects

Genitourinary side effects have included genital moniliasis (2.1%).

Other side effects

Amoxicillin-clavulanate may cause false-positive urine glucose tests in patients using Clinitest(R) tablets. Enzymatic glucose oxidase tests should be used during amoxicillin-clavulanate therapy.

Other side effects

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.

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