Cantharidin is classified as super toxic. Probable oral lethal dose in humans is less than 5 mg/kg or a taste of less than 7 drops for a 70 kg (150 lb.) person. It is very toxic by absorption through skin.
white to light yellow crystal powde
Brown to black powder or plates or scales. Formerly used as a counterirritant and vesicant. Used for the removal of warts. Used as an experimental anti tumor agent. Active ingredient in spanish fly, a reputed aphrodisiac.
Cantharidin is a natural toxin produced by blister beetles that moderately inhibits protein phosphatases 1 (PP1) (IC50 = 1.7 μM) and PP2A (IC50 = 0.2 μM) and only weakly inhibits the activity of PP2B (IC50 = 1 mM). It has been shown to stimulate cell cycle progression and induce premature mitosis, used topically (0.7%) as an anti-wart treatment, and has been shown to be active in cervical, tongue, neuroblastoma, bone, leukemia, ovarian, colon, and various other cancer cell lines.
Cantharidin is a natural toxicant of blister beetles. Cantharidin has been used as a medicinal agent for over 2000 years and is listed as a drug under the name of Mylabris in the medical monograph Materia Medica published in 77 AD. Some of the most ancient Chinese prescriptions (306–168 BC) refer to the use of Mylabris for the treatment of furuncles and piles.
Cantharidin can be used for topically (0.7%) treatment of warts, in which the skin under the wart blisters, thereby, lifting the wart off the skin. It is used to treat molluscum contagiosum. Cantharidin is a strong inhibitor of protein phosphatases types 1 (PP1) and 2A (PP2A), which are potentially novel targets for anticancer therapies. Thus, cantharidin is exploited as anticancer drugs. Cantharidin is shown to be cytotoxic to cancer cells and stimulatory on the bone marrow. The renal toxicity of this drug has prevented its use in mainstream oncology.
Natural toxin inhibitor of protein phosphatases 1 and 2A (K i values are 1.1 and 0.19 μ M respectively); similar to okadaic acid (9,10-Deepithio-9,10-didehydroacanthifolicin ). Displays > 500-fold selectivity over PP2B.
When heated to decomposition Cantharidin emits acrid smoke and irritating fumes.
ChEBI: A monoterpenoid with an epoxy-bridged cyclic dicarboxylic anhydride structure secreted by many species of blister beetle, and most notably by the Spanish fly, Lytta vesicatoria. Natural toxin inhibitor of protein phosphatases 1 and 2A.
 Richard E. Honkanen (1993) Cantharidin, another natural toxin that inhibits the activity of serin/threonine protein phosphatases types 1 and 2A, 330, 283-286
 Jennette A. Sakoff, Stephen P. Ackland, Monique L. Baldwin, Mirella A. Keane, Adam
McCluskey (2002) Anticancer activity and protein phosphatase 1 and 2A inhibition of a new generation of cantharidin analogues, 20, 1-11
 Erin F. D. Mathes, Ilona J. Frieden (2010) Treatment of molluscum contagiosum with cantharidin: a practical approach, 39, 124-130
Organic anhydrides, such as Cantharidin, are incompatible with acids, strong oxidizing agents, alcohols, amines, and bases.