It has been studied in the treatment of warts but is of unclear benefit. Side effects
The most common side effects are flu-like symptoms and include fever, rash, dermatographism, hyperpigmentation, alopecia (hair loss), chills, and Raynauds phenomenon (discoloration of fingers and toes). The most serious complication of bleomycin, occurring upon increasing dosage, is pulmonary fibrosis and impaired lung function. It has been suggested that bleomycin induces sensitivity to oxygen toxicity and recent studies support the  role of the proinflammatory cytokines IL-18 and IL-1beta in the mechanism of bleomycin-induced lung injury. Any previous treatment with bleomycin should therefore always be disclosed to the anaesthetist prior to undergoing a procedure requiring general anaesthesia. Due to the oxygen sensitive nature of bleomycin, and the theorised increased likelihood of developing pulmonary fibrosis following supplemental oxygen therapy, it has been questioned whether patients should take part in scuba diving following treatment with the drug. Bleomycin has also been found to disrupt the sense of taste. Lifetime cumulative dose
Bleomycin should not exceed a lifetime cumulative dose greater than 400 units. Pulmonary toxicities, most commonly presenting as pulmonary fibrosis, are associated with doses of bleomycin greater than 400 units. Mechanism of action
Bleomycin, a non-heme iron protein, acts by induction of DNA strand breaks. Some studies suggest bleomycin also inhibits incorporation of thymidine into DNA strands. DNA cleavage by bleomycin depends on oxygen and metal ions, at least in vitro.
The biosynthesis of the bleomycin aglycon can be visualized in three stages:

NRPS-mediated formation of P-3A from Ser, Asn, His, and Ala
PKS-mediated elongation of P-3A by malonyl CoA and AdoMet to yield P-4
NRPS-mediated elongation of P-4 by Thr to P-5 that is further elongated by β-Ala, Cys, and Cys to get P-6m.On the basis of the bleomycin structure and the deduced functions of individual NRPS and PKS domains and modules, a linear model for the bleomycin megasynthetase-templated assembly of the bleomycin peptide/polyketide/peptide aglycon was proposed from nine amino acids and one acetate. Biosynthesis of bleomycin is completed by glycosylation of the aglycones. Bleomycin naturally occurring-analogues have two to three sugar molecules, and DNA cleavage activities of these analogues have been assessed, primarily by the plasmid relaxation and break light assays. History
Bleomycin was first discovered in 1962 when the Japanese scientist Hamao Umezawa found anticancer activity while screening culture filtrates of Streptomyces verticillus. Umezawa published his discovery in 1966. The drug was launched in Japan by Nippon Kayaku in 1969. In the US, bleomycin gained FDA approval in July 1973. It was initially marketed in the US by the Bristol-Myers Squibb precursor, Bristol Laboratories, under the brand name Blenoxane. Research
Bleomycin is used in research to induce pulmonary fibrosis in mice. See also
Flagellate pigmentation from bleomycin
Pingyangmycin (Bleomycin A5)

References
Further reading
External links
"Bleomycin". Drug Information Portal. U.S. National Library of Medicine. "Bleomycin". European Medicines Agency (EMA).