A Sydney-based model and cosmetic doctor has been referred to health authorities by the anti-doping watchdog after he enthusiastically endorsed muscle-building peptides.

In an article published in Executive Style in November Dr Django Nathan said "quite a few doctors I know are using [peptides] because they have so many beneficial effects and so few side effects".

Dr Django Nathan in an image on his personal website. Credit:djangonathan.com

The peptides he was using had not been rigorously tested in humans, he said, but said the risks were low.

He also suggested readers get their peptide prescriptions online. Fairfax Media found many Australian websites allow customers to apply for a peptide prescription from a doctor by simply filling out a five-minute questionnaire.