Adverse reactions to isoniazid on ingestion of fish with a high histamine content.

On eating preparations of a particular variety of fish, the skipjack (bonito), patients with tuberculosis on isoniazid repeatedly developed symptoms very similar to those of histamine poisoning. Skipjack was found to contain probably the highest concentration of histamine reported in fish. Isoniazid is a potent inhibitor of histaminase which normally plays an important role in the metabolism of histamine in the body. It is suggested that the symptoms seen in these patients were, in fact, due to histamine. In these circumstances the high histamine content of skipjack and the interference by isoniazid with the metabolism of the amine presumably play complementary roles in the production of histamine poisoning; each of these factors by itself is apparently inadequate to produce such intoxication. An analysis of the symptoms manifested by 21 patients is presented.