GI disturbances especially nausea & unpleasant metallic taste. Vomiting, diarrhoea or constipation; furred tongue, glossitis & stomatitis may be associated w/ an overgrowth of Candida; weakness, dizziness, ataxia, headache, drowsiness, insomnia, changes in mood or mental state eg, depression or confusion; peripheral neuropathy (high doses or prolonged treatment); temporary moderate leucopenia & thrombocytopenia; urethral discomfort & darkening of the urine.