Niacin Overdose

It would be unlikely for animals to be given chronic niacin overdoses. 

Niacin is a safe drug to use and its toxicity is dose related. Niacin toxicity has been shown to manifest itself as altered mental status, nausea and vomiting (Mittal et al. 2007). Evidence shows that excess niacin can cause hepatic dysfunction with associated coagulopathy, jaundice and fulminant liver failure (Etchason et al. 1991 Fischer et al. 1991). In addition niacin overdose can cause impaired glucose control (Mittal et al. 2007). 

The effects of most vitamin B overdoses have not been documented, although large dosages of pyridoxine have been reported to cause peripheral neuropathies. Ataxia and numbness of the hands and feet and impairment of the senses of pain, touch, and temperature may result. Excessive niacin intake may result in flushing, pruritus, and gastrointestinal disturbances. These symptoms are due to niacin s ability to cause the release of histamine. Large dosages of niacin can result in hepatic toxicity. 

IV. Diagnosis of vitamin overdose is usually based on a history of ingestion. Cutaneous flushing and pruritus suggest a niacin reaction but may be caused by other histaminergic agents. 

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