Are there any side-effects from using Wartner Verruca & Wart Removal Pen

There are a number of possible side-effects:

Using the Wartner Verruca & Wart Removal Pen may cause some discomfort (transient tingling, burning sensation). In case of small warts, there is higher chance of wounding or discomfort. Therefore the application should be limited to 1 time a day.
Always use the Wartner Verruca & Wart Removal Pen very carefully and accurately. If you’re not careful, scars and minor skin damage may occur.