Cantheridine blistering tissue, in original wrapper, by T.B. Brown, English

Cantharidine is a substance secreted from a type of beetle, commonly known as the ‘Spanish fly’. It was used as a counter-irritant, the technique being to irritate one part of the body, raising blisters on the skin, in order to relieve it in another. Care had to be taken when applying the cantharidine tissue, as it could cause excessive damage if not used cautiously. It was recommended that a handkerchief or piece of linen be placed over it when used on adults – a cabbage leaf was recommended for children.