May cause idiosyncratic reaction (chills, fever, hypotension, mental confusion, and wheezing) usually after the first or second dose (bleomycin is contraindicated in known hypersensitivity or idiosyncrasy to the drug). May produce pulmonary fibrosis. Caution when administering O~2~ during surgery to patients who have received bleomycin (may promote pulmonary toxicity). Avoid use in underlying lung disease or lung metastases. May cause pleuropericarditis, or Raynaud’s phenomenon. May cause renal toxicity. Bleomycin should be administered with extreme caution to patients with clinically important impairment of renal function or compromised pulmonary function. Risk of developing dose-related adverse mucocutaneous effects (e.g. erythema, hyperpigmentation, rash, skin tenderness, striae, vesiculation, and less commonly hyperkeratosis, nail changes, alopecia, pruritus, stomatitis). Hepatic toxicity may occur at any time after bleomycin initiation. Bleomycin has been shown to be mutagenic in vitro and in vivo, although it is not known if bleomycin is carcinogenic in humans (an increased incidence of nodular hyperplasia, site fibrosarcomas and various renal tumors observed in rats).