A viral wart is a very common benign growth of the skin caused by infection with human papillomavirus (HPV), commonly seen on the hands and feet.
Viral warts on the feet are usually very stubborn as the skin on your soles are usually thick. Hence it takes a while for the acid to dissolve the thickened skin caused by the virus. The ideal way of using the acid is to file it with a pumice stone (do not share it with anyone!), use the acid drop/paint every night, followed by the application of duct tape. Duct tape should be removed in the morning. Treatment duration is roughly between 1-3 months. Stop this treatment once you feel some burning sensation. If you do not see any improvement after a month, please see a dermatologist. Please avoid using a corn plaster.
You can see a dermatologist. As the wart continues to grow, the affected skin will be thick and with the weight pressure on the affected foot, it can cause tremendous pain-causing abnormal walking gait. In such a situation, please see your dermatologist soon. Treatment options such as cryotherapy (using liquid nitrogen and more powerful than a commercial portable histofreezer), surgical removal or laser can be used. Cryotherapy usually requires several sessions to see improvement. In such a scenario, carbon dioxide laser can be used to vaporise the warts, and this method may need fewer sessions compared to cryotherapy. Surgical removal of the wart is usually painful and will need bed rest for a few days, and will take approximately 4- 8 weeks to recover completely.
Many of the treatment options such as cryotherapy or laser are painful for a young child to handle. I would normally recommend topical acid first for at least 1 month or so. If you feel that your child is mature and could tolerate the pain, have a chat with him before coming to see a dermatologist. Educate your child not to touch other body parts with the affected fingers or others as it is contagious.