Does this chemical really make you fall in love?

Love, inside the brain, is a chemical cocktail of many different hormones.

Oxytocin — which is often called the “love hormone” — is believed to be the most important of all.

But it is nothing more than an ancient chain of nine amino acids, produced by all mammals, with similar molecules found in fish, reptiles and worms.

It helps induce contractions in childbirth, which is how it got its name: From the Greek oxys (swift) and tokos (birth). 

“There’s nothing inherently social about oxytocin,” said Sarah Winokur, a neuroscientist at the NYU Grossman School of Medicine.

So how did oxytocin get its reputation for making love happen?

Oxytocin, the wonder drug?

In the 1990s, an Emory University research group experimented on prairie voles, a rodent species that forms long-term monogamous relationships. They found oxytocin was essential in this behavior.

But the real hype around oxytocin started when researchers discovered it played a similar role in humans.

A 2005 study had participants play a trust game, where they had to decide whether to give money to a second player. The money given would be tripled, after which the second player could freely decide how much to keep and how much to return. 

This, of course, put the first player at risk of being betrayed.

Half the participants received synthetic oxytocin via nasal spray, the other half a placebo. The result? Those under the influence of oxytocin invested more money, trusting the second player more.

This study had a massive impact on the public and in the research community. As one of the study’s researchers said, oxytocin was a “trust molecule.”

It even saw one company in the US begin selling bottled oxytocin with the promise of enhancing personal relationships. Between 2004 and 2011, Google searches for “oxytocin nasal spray” went up 5000%.

In 2009, the effects of nasal spray oxytocin were tested again by Swiss researchers who invited couples to talk about a topic they often argued about. Again, half the couples received oxytocin via nasal spray.

Under the influence of oxytocin, couples had more constructive discussions, held more eye contact and shared their feelings more openly.

Love in a bottle?

Could synthetic oxytocin be a kind of real-life love potion?

Perhaps not.

In 2020, a Belgian researcher found a serious problem: Many of the studies into oxytocin’s effects couldn’t be replicated. That means when researchers tried running the same experiments again, results were often different.

This was also the case for the famous 2005 trust study. When it was replicated 15 years later with a larger number of participants, the effect disappeared — participants who got oxytocin behaved no differently from those who got a placebo.

A more recent study on prairie voles showed that even when scientists genetically removed the animals’ oxytocin receptors, the voles still formed pair bonds.

And there’s another problem.

“If you’re going to give people oxytocin to help them fall in love, it might also come with side effects,” said Winokour.

Oxytocin doesn’t only have positive effects. It has also been found to cause more negative feelings like aggression, envy and even schadenfreude, especially toward individuals that a person doesn’t consider part of their social group.

So does oxytocin forge attraction and build bonds, or does it increase aggression?

“It helps turn up the volume for things that are relevant in your social world,” said Winokur.

“It’s not as simple as saying ‘Oh, you just love everyone when there’s oxytocin around.'”

Edited by: MW Agius