Nausea, vomiting, diarrhea, pseudomembranous colitis, loose stools, abdominal pain, dyspepsia, heartburn, anorexia, bloating, skin rash, pruritus, urticaria, erythema multiforme, SJS, serum sickness-like reactions, dizziness, headache; transient increase of SGOT/SGPT & alkaline phosphatase; shock; granulocytopenia or eosinophilia, thrombocytopenia, interstitial pneumonia, stomatitis or candidiasis; vit K deficiencies; false +ve result of urine glucose test w/ Benedict's or Fehling's soln & Clinitest.