The cause-and-effect relationship between toads and warts is traditional. Some people believe that simply the touch of the toad’s skin is sufficient to cause warts to develop, while others think that it is the toad’s urine which produces them.
So, do toads cause warts? No, toads never cause warts but most toads secrete an irritating and poisonous substance which in some species may actually burn or irritate the skin of anyone who handles them incautiously.
Due to this reason toads have been through the bad publicity of causing warts. Also, many frogs and toads have a tendency to urinate when they are seized, and if the urine gets into a broken place in the skin it produces a burning sensation. But neither the poison nor the urine causes warts.