While amoxicillin is generally well-tolerated, it is important for patients to be aware of potential side effects. Common side effects include nausea, vomiting, diarrhea, and skin rashes. Serious allergic reactions, though rare, can occur and may present as hives, difficulty breathing, or swelling of the face and throat. Patients with a known allergy to penicillin or cephalosporins should avoid amoxicillin altogether.