Should toothpaste be used? why not. It is cost effective , available everywhere in plenty and in all seasons and is highly effective. However in case of acne, for a single acne one could apply it with a toothpick on acne itself. But use liberally it can dry out and irritate the skin. Chronic severe acne must not be allowed to be treated by toothpaste and must be consulted by dermatologist at earliest.