Duct tape occlusion therapy
Duct tape occlusion therapy (DTOT) is a method for treating warts, especially verrucas (plantar warts), by keeping them covered with duct tape for an extended period. Duct tape is now commonly referred to as a potential treatment for verrucas and warts.
Scientific evidence into the effectiveness of wart treatments, including the use of duct tape, is inconclusive due to the inadequacies of the studies that have taken place. Gibbs et al reviewed 52 trials, concluding, "The evidence provided by these studies was generally weak because of poor methodology and reporting." Professor Hywel C Williams, described the history of Randomized Controlled Trial (RCTs) into viral warts as "largely a shambles". A more recent meta analysis of 85 trials also concluded, "providing a useful idea of 'what works' from such a wide range of studies was difficult as many studies were of poor quality." 
Jerome Z Litt appears to be the first to suggest that adhesive tape could be used to treat warts. In 1978 he suggested, "My method is safe, easy, simple painless, inexpensive, and highly effective." His hypothesis for why this works has not been adequately tested in trials, he said, "It cannot be all "hypnotic" or "suggestive." Could it be that the airtight occlusion and a chemical reaction set up by the adhesive in the tape might combine to release a chemical or "toxin" causing the formation of antibodies? Whatever it may be, it works. I recommend that you try it."
The strongest evidence of the efficacy of Duct Tape Occlusion Therapy in the treatment of warts comes from a study by Rick Focht et al. Focht et al treated 51 children/young adults from aged 3 to 22 with either standard duct tape with rubber based adhesive, or cryotherapy (liquid nitrogen). They found the duct tape treatment significantly more effective than the cryotherapy (P=0.05) with 85% in the Duct Tape treatment group having a complete resolution of their wart, compared to 60% in the cryotheraphy group.
There are various criticisms of this study. Hywel Williams points out the lack of a placebo (control) group  and Gibbs et al noted that a number of outcome assessments were done over the telephone. There was also no reported longer term follow up to ensure no recurrence of the warts. Further analysis and commentary of the study is available 
Notwithstanding these criticisms, this study gives the clearest indication that standard duct tape, with rubber based adhesive, has a positive effect on treating warts.
- Cut duct tape as close to the size of the wart as possible and apply it over the wart
- Keep it on for 6 days (if the tape falls off for any reason, quickly replace it with a new bit)
- On the evening of the 6th day, take the duct tape off
- Wash and soak the foot and debride the wart with an emery board or pumice stone
- Leave the wart exposed for this one night
- Next morning, re-apply some new duct tape and wait until the evening of the 7th day before removal
The procedure should repeat week-by-week up to about 2 months.
Follow-up studies used different Duct Tape
Two other studies failed to repeat the success Focht et al. Despite serious flaws in these subsequent studies, they have called into question whether duct tape is effective for treating warts, particularly in the comprehensive meta analyses that have been conducted. The most obvious flaw in both of these studies is that they did not use regular duct tape, they instead choose a clear version of duct tape which has a completely different adhesive, namely acrylic based as opposed to rubber based (as pointed out by Wenner et al, and subsequently noted by Curt Samlaska, Assistant Professor of Medicine, University of Nevada School of Medicine, in response to a further review of these findings which failed to take this into account ). Even the earliest work in this field suggested the glue on the tape may be why this treatment works  so it is perhaps not surprising that different results are found when using different kinds of tape.
A study led by Rachel Wenner into the effectiveness of duct tape occlusion compared its effect with a control group that used moleskin. In fact, in the treatment group using duct tape, moleskin was applied over the duct tape so that the patient couldn't visually tell if they were treated with duct tape or just moleskin. The huge flaw in this experiment was that regular duct tape was not used. They instead choose to use clear duct tape, which has a different glue to regular duct tape. Clear duct tape has an acrylic based glue and regular duct tape has a rubber based glue (as described by Wenner et al in their paper). Wenner also reports that the moleskin also has an acrylic based glue. So, Wenner's 2 treatment groups both used patches with acrylic based glue. It seems hardly surprising that there was no statistically significant difference in results reported between the 2 groups.
A second trial also used the same 3M clear duct tape for the treatment group which has an acrylic-based glue as described by Wenner. They too found only modest but non-significant effect on wart resolution. The statistical power of the latter trial has been questioned.
A Popular Mechanics article found 3M transparent duct tape to have a "lackluster grip" which corresponds to DeHaen's finding that only 19% of respondents found the stickness of the transparent duct tape "good".
Studies have provided an indication that Duct Tape Occlusion Therapy can be effective in treating warts (particularly Focht et al ). Some medical advice now suggests duct tape to their patients as a treatment for warts and verrucas.
Other studies, like that of Wenner  and  have not found 'duct tape' to be effective but on scrutiny of their published papers it is clear that the "duct tape" they used was not a standard duct tape - it was clear tape and had a different glue than regular duct tape. These studies, which failed to replicate the results of Focht et al, have been widely cited, e.g. in the Cochrane meta analyses, though these subsequent citations do not take account of the different duct tape used in these trials.
Further studies are necessary to properly confirm the effectiveness of this treatment.
- "Warts and verrucas - Treatment". nhs choices. Retrieved August 24, 2013.
- "Warts and Verrucas". www.patient.co.uk. Retrieved August 24, 2013.
- "How to get rid of warts". American Academy of Dertmatology. Retrieved August 24, 2013.
- "Warts and Verrucas". Bupa. Retrieved August 24, 2013.
- Jennifer DeMichele (July 2003). "A New Medical Breakthrough: Wart to do when Verruca vulgaris Attacks". Journal of Young Investigators. Retrieved August 24, 2013.
- Mayo Clinic Staff. "Plantar Warts". The Mayo Clinic. Retrieved August 24, 2013.
- Tom Biernacki (15 April 2013). "Verruca Duct Tape Removal Treatment Method". Detroit Foot Clinic. Retrieved August 24, 2013.
- Gibbs, S; Harvey, I; Sterling, JC; Stark, R (2003). "Local treatments for cutaneous warts". Cochrane Database of Systematic Reviews (Cochrane Skin Group) (3). doi:10.1002/14651858.CD001781. Retrieved 24 August 2013.
- Williams, Hywel (2003). "Commentary on 'Duct tape occlusion treatment increased resolution in common paediatric warts'". Evidence Based Medicine (British Medical Journal) 8 (2): 58. doi:10.1136/ebm.8.2.58. Retrieved 24 August 2013.
- Kwok, CS; Gibbs, S; Bennett, C; Holland, R; Abbott (2012). "Topical treatments for cutaneous warts.". Cochrane Database of Systematic Reviews (Cochrane Skin Group) (9). doi:10.1002/14651858.CD001781.pub3. Retrieved 24 August 2013.
- Litt JZ (December 1978). "Don't excise--exorcise. Treatment for subungual and periungual warts". Cutis 22 (6): 673–6. PMID 720133.
- Focht DR, Spicer C, Fairchok MP (October 2002). "The efficacy of duct tape vs cryotherapy in the treatment of verruca vulgaris (the common wart)". Archives of Pediatrics & Adolescent Medicine 156 (10): 971–4. PMID 12361440.
- Miller KE (February 2003). "Duct tape more effective than cryotherapy for warts". American Family Physician 67 (3).
- Wenner R, Askari SK, Cham PM, Kedrowski DA, Liu A, Warshaw EM (March 2007). "Duct tape for the treatment of common warts in adults: a double-blind randomized controlled trial". Archives of Dermatology 143 (3): 309–13. doi:10.1001/archderm.143.3.309. PMID 17372095.
- Samlaska, Curt (2012). "Response to 'Question 3 What is the efficacy of duct tape as a treatment for verruca vulgaris?'". Archives of Diseases in Childhood (British Medical Journal) 96 (9): 897–899. doi:10.1136/archdischild-2011-300533. Retrieved 24 August 2013.
- de Haen M, Spigt MG, van Uden CJ, van Neer P, Feron FJ, Knottnerus A (November 2006). "Efficacy of duct tape vs placebo in the treatment of verruca vulgaris (warts) in primary school children". Archives of Pediatrics & Adolescent Medicine 160 (11): 1121–5. doi:10.1001/archpedi.160.11.1121. PMID 17088514.
- Van Cleave J, Kemper AR, Davis MM (November 2006). "Interpreting negative results from an underpowered clinical trial: warts and all". Archives of Pediatrics & Adolescent Medicine 160 (11): 1126–9. doi:10.1001/archpedi.160.11.1126. PMID 17088515.
- Sawyers, Harry (February 2009). "What's the Best Tape? Abusive Lab Test". Popular Mechanics.