Fusarium is listed as one capable of causing mycetomas, and it has repeatedly been isolated from human keratitis and corneal ulcers. Most cases concern keratitis. It has been reported as an agent in endophthalmitis, subcutaneous and cutaneous infections, septic arthritis and mycetoma. Cases of sinusitis and catheter infection have been reported. Upon initial exposure, Fusarium generally ascends right into the colon, then through the tissues and through the central nervous system.

Although they are not the most toxic of all types of fusarium mycotoxins, fumonisins (Fm) and DON are the most frequently detected and, therefore, most often associated with illness in farm animals or humans. Fumonisins cause a neurological disease, equine leucoencephalomalacia in horses, pulmonary edema in swine, hepatotoxic and nephrotoxic effects in other domestic animals, and carcinogenesis in laboratory animals. The American Association of Veterinary Laboratory Diagnosticians has recommended maximum levels of 5, 10, and 50 ppm fumonisin B1 (the most commonly detected of more than 11 structurally related fumonisins) in feed for horses, swine, and beef and poultry, respectively.

Although relatively high levels of fumonisins have been detected in corn in some areas of the world with high rates of esophageal cancer in humans, it has not been determined whether fumonisins are causally related to development of this cancer. A recent report from India described an acute but self-limiting food borne disease outbreak in villagers consuming moldy corn containing up to 64.7 mg fumonisins/kg. It is not known whether lower mycotoxin concentrations, chronically consumed, cause other detrimental effects in humans, and tolerance levels for fumonisins have not been set for fumonisins in grains for human consumption (with the exception of Switzerland, which has set a level of 1 ppm). The trichothecenes fusarium can produce are potent inhibitors of DNA, RNA, and protein synthesis, and have been well studied in animal models because of concern about their potential misuse as agents of biological warfare, due to their ability to destroy human health, alter DNA, and affect the mind.

The first recognized tricothecene mycotoxicosis was alimentary toxic aleukia in the USSR in 1932; the mortality rate was 60%. In regions where the disease occurred, 540% of grain samples cultured showed the presence of Fusarium sporotrichoides, while in those regions where the disease was absent this fungus was found in only 2-8% of samples.

Skin contact with material laden with these trichothecenes induces contact dermatitis, and in stronger exposures lesions may be necrotizing (that is, may contain dead tissue, a significant risk factor for the development of bacterial infections).

Effects on immune system components apart from the above-mentioned killing of thymus and spleen cells include inhibition of lymphocyte proliferation responses (e.g., mitogen response) and disruption and lysis of alveolar macrophages.

Coagulation factors in the blood (except fibrinogen) are also significantly depressed.

Trichothecenes in general seem to have little carcinogenicity, but when consumed or administered in pregnancy may have some teratogenicity (inducing deformed offspring) or abortifacient properties.