1. The main constituent in GSL wart and verruca treatments is salicylic acid, which is what this patient appears to have been using. Perseverance in their use is necessary - manufacturers of even the strongest (up to 50% salicylic acid)  P classified products recommend up to 12 weeks of treatment - so first check if this patient has been using them for long enough. Another approach to treatment is cryotherapy and OTC freezing agents for warts and verrucas are available, as are treatments containing silver nitrate, glutaraldehyde and trichloroacetic acid. But in this case the patient may get a faster and more effective, although rather more expensive, resolution to his problem if you refer him on to a podiatrist.