Is it safe to use ordinary household cyanoacrylate glue as a medical glue? According to Reference 7, most cyanoacrylate glues not designed specifically for medical use are formulated from methyl-2-cyanoacrylate, since it produces the strongest bond. Not only can such glues irritate the skin, during polymerization they can generate significant heat, to the point of causing skin burns. I gather this is a problem only if a large area of skin is affected. But to err on the side of safety, you should tell your brother-in-law he should only use medically-approved glue, not the ordinary kind.