One of the in-office treatment options for plantar warts includes Cantharidin (Canthrone), a blistering agent or vesicant (vesicle is the medical term for blister, so a vesicant is a blister maker) made from an odorless, colorless compound secreted from over 1500 species of blister beetles.(1,2)
As a kid, I watched the cartoon Beetlejuice, an American-Canadian cartoon loosely based on the 1988 film of the same name (starring Michael Keaton and Alec Baldwin). and so dedicate this blogpost to the makers of that entertaining kid’s show This Tim Burton cartoon series focuses on the life of a “goth girl, Lydia Deetz and her undead friend Beetlejuice as they explore The Neitherworld, a wacky afterlife realm inhabited by monsters, ghosts, ghouls and zombies. As in the film, Lydia could summon Beetlejuice out of the Neitherworld (or go there herself) by calling his name three times, sometimes as part of a set chant:
“Though I know I should be wary,
Still I venture someplace scary;
Ghostly hauntings I turn loose …
Beetlejuice, Beetlejuice, Beetlejuice!” (3)
Because this compound works so well on warts, we don’t even need to jokingly create a chant that finishes with, “Beetlejuice, Beetlejuice, Beetlejuice!” because the wart disappears!
After trimming down the callus with a scalpel, Cantharidin is applied to the wart and covered with an occlusive dressing for 24 hours. Although this in office treatment does not hurt, the treatment causes a blister to form. This blistering may cause pain. In college, I had this treatment performed on my plantar warts. For me, the blistering was the worst part of the plantar wart treatment. Granted, I was experiencing pain prior to seeing the podiatrist and within four weeks the warts were gone. Scarring does not occur due to how the medication interacts with the skin (see below – Mechanism of Action). I was part of the 80% of cases in which this treatment will cure the wart.4 Occasionally, this treatment may take reapplication every 2 weeks. A two-month period of watching for signs of regrowth should be undertaken before officially calling the wart cured.
How it works – Mechanism of Action
The skin is made up of many layers as shown below. The outer layer, or epidermis is where the medication is absorbed. Cantharidin is absorbed by the lipid layers that layer. Then, the medication activates an enzyme, a neutral serine protease, that causes the breakdown of the intercellular connections, a process called acantholysis. Since this happens in the outer layer of skin, scarring will not occur.(1) And because the 1988 Beetlejuice film was in the Horror-film category, may I wish you an early Happy Halloween!
1. Moed L, Shwayder A, Chang MW. Cantharidin Revisited – A Blistering Defense of an Ancient Medicine. Arch Dermatol. 2001;137(10):1357-1360