Treating Resistant Warts with Cantharidin

By Valerie Hanft, MD October 19, 2018 No Comments

Cantharidin wart treatment

Of all the common skin conditions, patients often cite warts as one of the most troublesome and undesirable. A wart is a viral infection of the skin. While generally harmless, warts can grow on nearly any part of the body. On the face and tops of the hands, warts are raised. On the soles of the feet, the tissue becomes thickened from the pressure of standing and the warts (called plantar warts) are flatter. Warts have a rough surface on which tiny, dark dots can often be seen.

Two of the easiest and most frequently used methods of getting rid of a wart are topical salicylic acid treatments and cryosurgery (freezing the wart off using liquid nitrogen). There are, however, some warts that resist both treatments. In these cases, there is another option for eliminating the wart: Cantharidin.

What Is Cantharidin?

Cantharidin is an odorless and colorless chemical derived from blister beetles. In nature, male blister beetles secret cantharidin during mating. The female blister beetle then uses the secretion to cover her eggs in order to protect them from predators. (Source)

In large doses, cantharidin is a powerful poison and burn agent. For dermatological purposes, properly dosed cantharidin can be used for causing strategic blistering of the skin.

How Does Cantharidin Remove Warts?

When topically applied to a wart, cantharidin causes controlled blistering underneath the skin. It also triggers the release of an enzyme which breaks the bonds that hold skin cells together. Eventually the blistering below the wart combined with a deterioration of cellular adhesion causes the wart to become detached and peel off.

How Is the Treatment Performed?

Cantharidin should be administered by a physician who has experience in its use. The doctor “paints” the cantharidin directly on the wart before covering it with a bandage.

How Effective Is Cantharidin?

Cantharidin is a very effective wart treatment, often working well on warts that resist other treatments. The application of cantharidin is minimally painful and there is no scarring, making it a great option for young children or on warts that appear on highly visible areas.

While cantharidin typically removes a wart in a single treatment, some patients may need follow up applications if the wart isn’t gone after one treatment.

Are There Any Side Effects?

The side effects of wart removal via cantharidin are mild and can include tingling, itching, or burning sensation around the treatment area over the first few hours after being applied. The skin may also feel tender for 2-5 days following treatment. Since cantharidin can cause breaks in the skin, infection is possible, but extremely uncommon if the site is properly cared for and kept clean.


Valerie Hanft, MD

Valerie Hanft, MD is Board Certified by the American Board of Dermatology and is a member of the Travis County Medical Association. Dr. Hanft received her Dermatology specialty training at the University of Michigan. Her professional interests are in pediatric dermatology, clinical research and medical dermatology. Dr. Hanft sees patients at our Westlake location.

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