Blister Beetle Poisoning
Historically, blister beetles have been used in medicine. Dead and dried beetles were smashed and ground into a fine powder. The powder was used to create a seemingly mystic concoction called Spanish fly. People used Spanish fly to treat physical ailments such as arthritis and more salaciously as an aphrodisiac. The basis for these uses is because blister beetles produce cantharidin. The beetles employ the chemical as a means to defend themselves and their eggs. They release the chemical when agitated or attacked by predators.
Cantharidin is a vesicant, or in other words a chemical that causes irritations and blisters, hence the name blister beetle. Consumption of Spanish fly results in irritation to the urinary tract which in turn can result in sexual stimulation. This is the source of Spanish fly as an aphrodisiac. For all the apparent benefits, cantharidin also can have severe medical consequences and widely is viewed as a poison. The effects range from severe digestive issues, like diarrhea, to internal bleeding and kidney failure to possible death. Symptoms of poisoning can include the following: stomach pain, nausea, vomiting, bloody urine and possible coma.
If a person suspects they have been poisoned with cantharidin, medical physicians are able to run diagnostic tests to check for the presence of the chemical in urine and other body fluids. Unfortunately a direct counteragent is not available for treatment. Medical professionals employ standard oral antipoisoning treatments such as stomach pumping and an IV drip.
However, it is highly unlikely for a human to involuntarily ingest blister beetles. Livestock and horses are more likely to be poisoned than people, since the beetles are often found in hay and may be ground up in the harvesting process.