Oxytocin, the chemical in our brains known as the “love hormone,” is known to foster both trust and generosity between people, but now scientists are finding that it has a dark side, Scientific American reported on Wednesday.

Researchers at the University of Amsterdam discovered that the “love drug” may actually work best at promoting love among people of similar backgrounds and, rather than love, can lead to ethnocentrism, prejudice and xenophobia.

In experiments, male Dutch volunteers inhaled either oxytocin or a placebo. In word association experiments, the volunteers given oxytocin were far quicker at ascribing positive attributes to Dutch names. They were less likely to make a positive association with German names and far less likely to link kind words to Arab names.

Until now, the role of oxytocin in social behavior focused only on whether and how it created altruistic responses. It is known to help bond mothers to their children and scientists studying this relationship have theorized it may be involved in maternal aggression.

“Our findings and those of other indicate that oxytocin should not be used for recreational purposes,” wrote study author Carsten de Dreu in an article in the Proceedings of the National Academy of Sciences. “And while oxytocin may help in therapeutic settings, much more controlled research is needed -- there is a lot we do not yet know about oxytocin.”

It is not known exactly how oxytocin operates in the brain, although some scientists believe it reacts with a part of the brain that controls fear.