General practitioners who change tracks to become aesthetic doctors can earn an extra $1 million a year.

A simple estimate: A doctor can charge up to $500 for each skin whitening injection, according to a report in Shin Min Daily. In contrast, takings for treating common ailments like coughs and colds amount to about $40 per patient.

In other words, giving one whitening shot is equivalent to treating more than seven patients for a cold. Other aesthetic treatments aren't cheap either. For example, mesotherapy can cost from $150 to $750.

Concerned about the proliferation of such treatments that have not been scientifically proven to be effective, the Health Ministry told Shin Min Daily that doctors found using such treatments will be referred to the Singapore Medical Council for action. Doctors who work with beauty salons will also be affected by this new ruling.

The Health Ministry has targeted three aesthetic treatments for scrutiny. These are:

1) Mesotherapy: A non-surgical procedure where tiny injections are made to the are below the skin. It claims to dissolve fat, allowing it to be carried through the bloodstream and expelled from the body.
2) Colon cleansing: Water is passed into the colon to get rid of waste that is lodged in the wall of the colon. It is said to improve the skin, improve digestion and lead to weight loss.
3) Skin whitening