No carcinogenicity studies have been conducted with Omadacycline, however, other tetracycline drugs have shown oncogenicity.FDA Label Specifically, oxytetracycline increased incidence of adrenal and pituitary tumors and minocycline increased incidence of thyroid tumors.

Omadacycline has tested positive for clastogenicity and aneugenicity during in-vitro Chinese hamster ovary cell studies and for mutagenicity in mouse lymphoma cells.FDA Label Both positive results occurred in the presence of metabolizing enzymes. Omadacycline has tested negative for chromosomal aberration of any kind during in-vitro Chinese hamster V79 cell testing. It has further tested negative during in-vivo micronucleus assays in ICR mice and HanRcc: WIST rats.

Omadacycline reduced sperm counts and sperm-motility in male rats at repeat dosages equivalent to 1.3 times the normal human exposure but produced no effect on fertility parameters.FDA Label Inhibition of spermatogenesis was noted at repeat dosages equivalent to 6-8 times normal human exposure for a duration greater than 37 days but not at dosages under 2 times normal human exposure or durations of less than 4 weeks. Ovulation and embryonic survival was reduced in female rats at dosages approximating normal human exposure administered before mating through early pregnancy.

Thyroid hyperpigmentation, goitrogenicity, thyroid hyperplasia, and adrenal have been noted in multiple animal studies using other tetracycline drugs.FDA Label