Shock; rash, urticaria, erythema, pruritus or fever; granulocytopenia, eosinophilia, thrombocytopenia; rarely, increased SGOT & SGPT, alkaline phosphatase; renal insufficiency; pseudomembranous colitis, gastric discomfort, heartburn or anorexia, nausea, full-stomach sensation, constipation; interstitial pneumonia, changes in bacterial flora; vit K or B deficiency; headache or dizziness.