Warts (verrucas): what really works and what does not

The human papillomavirus infects cells of the basal layer of the epidermis, usually through tiny breaks in the skin. Infected cells multiply and the skin at that spot thickens: a wart forms. Infection happens through direct contact or indirectly through damp, shared surfaces such as the floors of swimming pools and showers. A wart can also spread to other areas of skin in the same person, for example through scratching or shaving.

A sensible practical lesson follows from this analysis: two warts that look alike can have a completely different course, because they are caused by different virus types. Plantar warts associated with HPV 1 largely healed on their own (58% with observation alone), whereas common warts associated with HPV 2/27/57 hardly at all (3%). This partly explains why some warts vanish quickly and others last for years, and why the results of treatment studies differ so much depending on the group studied.

It is also worth understanding what recurrence means. Treatment destroys the visible lesion but does not always remove the virus from the surrounding skin cells; if the immune system does not recognise the infection, the wart can reappear in the same place or next to it. That is why a single treatment is sometimes not enough, and an assessment of success should also take into account whether the lesion has come back after a few months.

The result raises an important question: in a healthy adult or child with a single wart, should you treat straight away? The untreated observation group in this trial had 16% cures after 13 weeks, and in plantar warts the differences between treatment and observation were not significant. The 2012 Cochrane review states in its background that viral warts can range from a minor nuisance that resolves spontaneously to a troublesome, chronic condition. Waiting is therefore an option, as long as the wart does not hurt, is not growing fast and does not get in the way of daily life.

At the same time, spontaneous resolution is not a reason to ignore a lesion indefinitely if it hurts (especially on the sole), bleeds or is spreading. The decision depends on preference and circumstances: a child whose wart does not bother them can wait, while a person with many warts or warts in pressure-bearing places will more likely want them treated. Because the trials we cite describe no time thresholds, it is hard to name the 'right' moment, so it is worth discussing it with a family doctor or pharmacist.

The authors of the review conclude that the evidence is more consistent for salicylic acid but shows only a modest therapeutic effect; cryotherapy did not do significantly better in comparisons with placebo and with salicylic acid, and adverse effects such as pain, blistering and scarring are probably more common after cryotherapy. More aggressive cryotherapy was more effective than gentle (RR 1.90; 95% CI 1.15-3.15), but with more adverse effects. None of the other treatments assessed was clearly safer or more effective than salicylic acid and cryotherapy.

For practice this means the following: in plantar warts salicylic acid and cryotherapy give comparable but modest results, and cryotherapy is a painful and costlier procedure. That is why salicylic acid is often chosen first, with cryotherapy kept for common warts or when home treatment has failed. Salicylic acid requires patience and regularity; in the trials it was applied daily for several weeks, and details (strength, skin preparation, protecting the healthy skin around the lesion) are given in the leaflet of the specific product, which we do not replace.

Why, then, did the method become so widespread? For several reasons: it is cheap, painless and available, and it looked promising in the first small studies. Later studies with a control group and blinding did not confirm it. A Dutch trial in children aged 4-12 (Efficacy of duct tape vs placebo in the treatment of verruca vulgaris, de Haen et al. 2006) gave, after 6 weeks, cure in 16% of children in the tape group and 6% in the placebo group (p=0.12), a difference not considered statistically significant; 15% of children in the tape group reported adverse effects such as erythema, eczema and wounds.

This does not mean that tape is harmful for everyone. If someone wants to try it, it should be on a lesion that does not hurt and does not need urgent treatment, with a check of the skin under the dressing and stopping if it becomes irritated. It must be recognised, though, that on current evidence there is no basis for expecting a better result than with no treatment.

Zinc is an element important for immunity, so the idea arose that it might help in treating warts. A 2025 meta-analysis (7 trials) found that complete clearance of warts was more frequent after oral zinc sulphate than in the control group (risk difference 0.288; 95% CI 0.087-0.489), with the effect largest in people with a low initial plasma zinc level (risk difference 0.767). In people treated with standard methods, adding zinc reduced the risk of recurrence within 6 months. The most common adverse effects were nausea and vomiting.

Intralesional immunotherapy (MMR vaccine, Candida antigen, vitamin D3 and others) consists of methods used for resistant warts in specialist clinics. A 2024 meta-analysis (24 trials) found that intralesional Candida antigen gave a significantly higher chance of complete clearance than saline alone (RR 5.39; 95% CI 3.49-8.33), but did not differ significantly from other immunotherapies, and the authors caution that the trials were small. These are methods for a doctor, not for self-treatment. The 2012 Cochrane review also noted that dinitrochlorobenzene (DNCB) can be effective in resistant warts (RR 2.12), while the results for bleomycin were inconsistent.

Children are a separate situation. Cryotherapy can be painful and poorly tolerated in them, and spontaneous resolution of warts is possible (in the CMAJ trial participants were aged 4 to 79, and the untreated observation group had 16% cures after 13 weeks), so in children a conservative approach with gentle remedies is often reasonable. The decision depends on severity, location and the family's preferences; it should be discussed with a paediatrician or dermatologist.

Warts are one of those problems where the guidance is simpler than the sheer number of tips on the internet. The evidence best supports salicylic acid applied persistently; cryotherapy has its place, particularly in common warts, but it is not a miracle solution and can be painful. Tape, zinc and home methods lack sufficient evidence. The biggest trap is impatience: giving up treatment too early or replacing it with another, equally ineffective method. The second trap is treating something that is not a wart, which is why, when in doubt, a doctor should confirm the diagnosis.