Amoxicillin Side Effects
Not all side effects for amoxicillin may be reported. You should always consult a doctor or healthcare professional for medical advice. Side effects can be reported to the FDA here.
For the Consumer
Applies to amoxicillin: oral capsule, oral powder for suspension, oral tablet, oral tablet for suspension, oral tablet chewable, oral tablet extended release
In addition to its needed effects, some unwanted effects may be caused by amoxicillin. In the event that any of these side effects do occur, they may require medical attention.
You should check with your doctor immediately if any of these side effects occur when taking amoxicillin:Incidence not known
- Abdominal or stomach cramps or tenderness
- back, leg, or stomach pains
- black, tarry stools
- bleeding gums
- blistering, peeling, or loosening of the skin
- blood in the urine
- bloody nose
- chest pain
- clay-colored stools
- dark urine
- diarrhea, watery and severe, which may also be bloody
- difficulty with breathing
- difficulty with swallowing
- fast heartbeat
- feeling of discomfort
- general body swelling
- heavier menstrual periods
- hives or welts
- increased thirst
- inflammation of the joints
- joint or muscle pain
- loss of appetite
- muscle aches
- nausea or vomiting
- pain in the lower back
- pain or burning while urinating
- painful or difficult urination
- pale skin
- pinpoint red spots on the skin
- puffiness or swelling of the eyelids or around the eyes, face, lips, or tongue
- red, irritated eyes
- redness, soreness, or itching skin
- shortness of breath
- sore throat
- sores, ulcers, or white spots in the mouth or on the lips
- sores, welting, or blisters
- sudden decrease in the amount of urine
- swollen, lymph glands
- tightness in the chest
- unpleasant breath odor
- unusual bleeding or bruising
- unusual tiredness or weakness
- unusual weight loss
- vomiting of blood
- watery or bloody diarrhea
- yellow eyes or skin
Some of the side effects that can occur with amoxicillin may not need medical attention. As your body adjusts to the medicine during treatment these side effects may go away. Your health care professional may also be able to tell you about ways to reduce or prevent some of these side effects. If any of the following side effects continue, are bothersome or if you have any questions about them, check with your health care professional:Less common
- Bad, unusual, or unpleasant (after) taste
- change in taste
- black, hairy tongue
- changes in behavior
- discoloration of the tooth (brown, yellow, or gray staining)
- trouble with sleeping
- unable to sleep
- white patches in the mouth or throat or on the tongue
- white patches with diaper rash
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 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 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 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 side effects have included crystalluria and acute interstitial nephritis, often associated with fever, rash and eosinophilia.
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 side effects have included mucocutaneous candidiasis and vulvovaginal mycotic infection.
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 side effects have included moderate elevations of AST (SGOT) and/or ALT (SGPT) levels, cholestatic jaundice, hepatic cholestasis, and acute cytolytic hepatitis.
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 side effects have included cough and rhinorrhea.
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