Diarrhea, stool changes. Moderate to severe diarrhea, nausea, abdominal pain, dyspepsia, vomiting & flatulence, pseudomembranous colitis; headache, dizziness; rash, pruritus, urticaria, drug fever, arthralgia; thrombocytopenia, leucopenia & eosinophilia, mild transient changes in liver & renal function tests; genital pruritus & vaginitis.