German researchers are testing an impotency treatment for men made using only natural ingredients that in some cases works better than Viagra, newspapers reported Monday.

"In clinical trials, 50 men had much better afterwards, more fun in bed and just generally felt better about themselves," the Sueddeutsche Zeitung daily cited Olaf Schroeder from Berlin's Charite hospital as saying.

"Their was even higher than the control group taking ," he said.

The potent cocktail includes tribulus terrestris, a herb already used in , a found in the Andes called maca and grape juice extract, newspapers said.

The treatment, dubbed "Plantagrar", is due to be launched in early 2010, the Bild daily said.

But some of those tested had unwelcome side effects.

"Two of the subjects had bad diarrhoea," the Berliner Kurier quoted Schroeder as adding.

(c) 2009 AFP