Google has announced it will ban online advertisements for an appetite suppressant that has come under fire in medical circles.

The search giant contacted some advertisers to inform them it would stop taking ads for ephedrine-based products "in the coming weeks".

The drug can also be used as a stimulant, concentration aid and decongestant and is often used in bodybuilding.

But doses were severely restricted under 1997 US legislation. Side effects can include angina, sweating, nausea, insomnia, confusion and pulmonary edema, according to British Medical Association documentation.

Despite the dangers, it is thought many people still buy large quantities of the drugs via online adverts.

One online marketer who had advertised ephedrine and received Google's notification wrote:

"It actually surprises me that it took this long for Google to make the move. Oh well, it was fun while it lasted."

Google last month added free-to-play gambling sites to its list of outlawed ads in its AdWords content policy.