Exposure to Methylene Blue

M-B tablets, Urolene Blue, TRA tablets, Urised Blue hair dyes 

Antidotes for methemoglobinemia and cyanide poisoning Biologic stains 

The same phenothiazines or closely related compounds which are used as psychotropic drugs or as sedatives in humans are used by veterinarians and farmers as insecticides and anthelmintics for animals and birds. Table 8 lists the commercial phenothiazine insecticides and wormers used by veterinarians. Many individuals in these professions have acquired allergic contact dermatitis, photoallergic reactions, or both by spraing such phenothiazines for insect control or feeding these compounds as wormers. Such individuals must avoid using phenothiazine antihistamines because of the likelihood of producing flares of the phenothiazine dermatitis. 

Methylene blue is 3,7-bis-(dimethylamino)phenozathionium chloride tetramethyl thionin chloride, a phenothiazine derivative used in various ways as shown in Table 9. In one observed individual who had acquired a photosensitivity from a phenothiazine compound, the administration of methylene blue urinary antiseptic produced a flare of the photodermatitis. 

Dilute mixtures of methylene blue, acid violet, and nigrosine are used as a color rinse for gray hair. Such rinses should be used with great care in those who have become sensitized to the phenothiazines. 

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Kidd SA, Lancaster PA, Anderson JC, Boogert A, Fisher CC, Robertson R, Wass DM. Fetal death after exposure to methylene blue dye during mid-trimester amniocentesis in twin pregnancy. Prenat Diagn 1996 16(l) 39-47. 

Table 9. Sources of exposure to methylene blue (a pheno-thiazine dye)...

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