The Curious Case of the "Love Molecule" (2025)

The scientific study of love has always been prone to a certain amount of controversy. Romantic love is a subject of endless fascination, but it is also sometimes seen as a bit of a frivolous topic for research. That academic ambivalence can lead to frustration when trying to find good information about the neuroscience that underlies passionate love and infatuation.

That leaves caring professionals who are tasked with helping clients manage feelings of heartache and obsessive love in a bind. How do they make sense of a powerful emotion when the evidence base is scattered and thin? Often, they have to rely on secondary sources, and this can create problems, such as what might be called "the curious case of phenylethylamine."

Numerous articles and posts that deal with the issue of love intoxication mention phenylethylamine (or PEA), describing it as a specific “love molecule” that is released in the brain and acts as a natural amphetamine.

Here are a couple of typical quotes:

Phenylethylamine is the hormone-like substance produced at the early stages of attraction that provokes the dizzy sensation some people feel when they’re falling in love.

During the heart-pounding excitement of new love, your brain releases lots of phenylethylamine (PEA). PEA functions like a natural amphetamine, so you really are high on love.

As I came across more and more of these articles, I began to feel a sense of disquiet. I’d been an academic neuroscientist for a quarter of a century, and I’d never heard of PEA having a significant role in the brain. Pretty embarrassing, considering I was writing a book about limerence and obsessive love.

Although I’d never encountered PEA in my academic work, the name suggested it was one of the many trace amines that add to the biochemical soup in the brain. The neuroscience literature is vast—far vaster than any one person can keep abreast of—and there’s always that nagging doubt that I’d missed a research niche far from my own specialism. It was time to start digging.

There was a burst of interest in what PEA might be doing in the brain in the 1970s and then 1990s as people were trying to sift through all the possible monoamine neuromodulators that contribute to behavioural regulation. PEA does resemble an amphetamine, chemically, but it doesn’t simply act like an endogenous amphetamine—in fact, elevation of PEA is linked to aggression, not euphoria. Other snippets of research found correlations between urine levels of PEA metabolites and various neurological conditions—depression, schizophrenia, and attention-deficit/hyperactivity disorder (ADHD) in particular. These findings (summarised in the review articles by Wolf & Mosnaim and Sabelli & Javaid cited below) are interesting but don’t make a case for PEA being a “love molecule.”

Offhand Comments, Chocolate Marketing, and Repetition

So how on earth did the idea that PEA was a natural amphetamine released in the brain that causes love come about? It seems to be a weird story of offhand comments, chocolate marketing, and repetition.

The original source seems to be Michael Leibowitz’s 1983 book The Chemistry of Love. In treating patients dealing with depression after a romantic breakup, Leibowitz found that a class of antidepressants called monoamine oxidase (MAO) inhibitors helped them. That’s not too surprising because MAO enzymes break down serotonin, noradrenaline, and dopamine—all highly relevant to mood regulation. However, in passing, he also mentioned that PEA is broken down by the same enzyme, and he speculated that maybe it was involved in the good vibes of love, too.

That’s it. That offhand comment seems to have started a snowball rolling.

There’s obvious appeal to the idea of a “love molecule,” and you can see how it would capture people’s imaginations. When an enterprising advertiser found out that chocolate contains PEA and presumably half-remembered some connection to love, he saw an opportunity. Eating chocolate obviously feels good because you get those “love feelings” that PEA delivers. Buy more chocolates on Valentine’s Day!

Combining the popular appeal of a specific love chemical in the brain with the desire for profit among chocolate sellers seems to have created an idea that was too good to check. Each new article cited the previous article as its source. This baton-passing continued until everyone forgot where the idea originated. The whole thing was a mirage.

On reflection, it’s not hard to see how such things can happen. If you aren’t a neuroscientist, why would you be skeptical about phenylethylamine? It sounds much like 5-hydroxytryptamine or anandamide or any of the other esoteric terms that only a specialist would recognise. You have to take it on trust that the author knows what they are talking about. Soberingly, it’s almost inevitable that I’ve similarly repeated common myths when writing about fields I know much less well then neurochemistry.

As a final note, I started chasing this story in earnest a few years ago when I was deep in the research for my book, but because of the frustrating merry-go-round and inconclusive nature of it all, I ended up not including anything about it in the final manuscript. Instead, I thought it might make a good blog post one day. Well, obviously, that day has arrived, but in going back now to check my sources, I came across a new “preprint” article that was deposited in July 2024 by Massimo Conti.

Evidently, Conti has chased the same mirage through popular science articles and newspaper stories. Admirably, he has put together a thoroughly cited and authoritative narrative about the curious case of phenylethylamine, and he also used the perfect metaphor for the experience: It’s just like Winnie the Pooh chasing the Woozle.

References