A woman listening to Neil Mitchell's talkback show was so shocked to hear her son talking on the radio about his drug use that she rang the show to say she was a former drug counsellor.

Kathe Baud rang 3AW today after hearing her son, Tom, describing on radio how he had used ecstasy, speed and psychedelic drugs.

She said she was "surprised" because she thought she would have recognised the symptoms of illicit drug use.