Duct tape and warts: how the HECK does it work?

Duct tape as a wart treatment is not alternative medicine.

Really. It's been studied a few times ... (emphasis mine):

Duct Tape More Effective than Cryotherapy for Warts - February 1, 2003 - American Family Physician (KARL E. MILLER, M.D.)

Focht DR III, et al. The efficacy of duct tape vs cryotherapy in the treatment of verruca vulgaris (the common wart). Arch Pediatr Adolesc Med October 2002;156:971-4.

Common warts (verruca vulgaris) are a common problem among patients who present in family physicians' offices. Although a significant number of warts will spontaneously resolve over two years, patients frequently request treatment to clear their skin of the lesions. Treatments such as cryotherapy, acid preparations, laser therapy, heat, and tape occlusion have been used in the management of warts, with cure rates ranging from 32 to 93 percent. However, most of these therapies are expensive, painful, or labor intensive. A few small, nonrandomized trials have studied the use of tape occlusion in wart treatment, with one study reporting cure rates of approximately 80 percent. Focht and associates compared the effectiveness of cryotherapy with duct tape applied to common warts.

The study was a prospective, randomized controlled trial with two treatment arms. Participants were patients three to 22 years of age who had viral warts and presented to a military clinic. Participants were randomized to receive cryotherapy or occlusive therapy with duct tape. Cryotherapy consisted of 10-second applications of liquid nitrogen to each wart every two to three weeks for a maximum of six treatments. The other group applied small pieces of duct tape to each wart. They were instructed to leave the tape in place for six days and were taught how to re-apply tape if it fell off. At the end of the sixth day, the patients removed the duct tape, soaked the wart in water, and gently debrided it with an emery board or pumice stone. The tape was left off overnight, then re-applied for another six days. This pattern was repeated for two months or until the wart resolved. Warts that did not resolve were measured. The main outcome measured was complete resolution of the wart.

In patients treated with duct tape, 85 percent of the warts completely resolved, compared with 60 percent in the cryotherapy group. These results were statistically significant. Resolution of warts treated with duct tape usually occurred within the first 28 days of therapy. If there was no response within the first two weeks, the warts were unlikely to respond to a longer course of therapy. The main adverse outcomes with duct-tape therapy were difficulty keeping the tape on the wart and minor skin irritation. The main adverse effect in the cryotherapy group was mild to severe pain at the freeze site during and after the treatment.

The authors conclude that duct tape occlusive therapy is more effective than cryotherapy in the treatment of common warts. They also state that duct tape therapy is less expensive and has fewer adverse effects than cryotherapy.

This business of treating warts in children with duct tape has been around for at least 16 years, but I've never really believed in it.

It's just so weird.

Then my 8yo developed a quite impressive toe wart. A flowering exuberant growth. It bugged him, but there was absolutely no way he was going to have it incinerated or freeze-burned. No friggin' way.

So we tried the weird duct tape treatment. An old silver roll.

Over the next few days, when we reapplied the tape, the wart started to look sickly. It's vessels appeared dusky, as though they were occluding. Then the entire toe started to appear mildly inflamed - swollen and red.

The next evening my son proudly displayed an impressive crater where the wart had been. It had fallen off. Within a few days the crater was gone, though I think there's some warty material remaining. (We're reapplying the tape.)

Ok, so there are skeptics, and if it does work then it's probably limited to children and adolescents with good immune systems. In these cases the immune system is perfectly capable of clobbering a wart, but first it has to recognize it as foreign.

So, how could it possibly work?

There, PubMed failed me. I couldn't find any interest in how this thing might work.

Doesn't that display a certain lack of imagination? Viral warts have many of the properties of tumors, and of course immune tolerance and rejection is important. Heck, apoptosis is still somewhat fashionable. Isn't anyone interested in how this treatment actually works?

I suspect this one runs into three problems:

1. It's so weird that most researchers don't believe it works.
   
2. If it works they figure this is some kind of "mind over immunology" thing, and there's no tenure in chasing that one.
3. Duct tape is cheap.
   

We need a bored tenured faculty person with an animal lab to study this in animals. If we found that duct tape cured animal warts we'd then be able to figure out what it's doing.

Update 8/31/08: The comments are interesting. I particularly like the suggestion a few degree change in local temperature might be enough to impact the wart/body war, though it's fair to mention that plantar warts thrive in a pretty warm environment.