Remember oxytocin, the so-called “love hormone”? Over the past few years, a series of well-publicized studies have suggested its activation inspires increased trust, altruism, and empathy.

But let’s hold off on any plans to inject it into tap water. Newly published research suggests the hormone, commonly associated with cuddling, may also inspire domestic violence.

“Far from being a panacea for all social ills,” writes a research team led by University of Kentucky psychologist C. Nathan DeWall, “oxytocin may have diversified effects, increasing the likelihood that people who are inclined toward physical aggression will inflict harm on their romantic partners.”

This raises the intriguing possibility that domestic violence could be decreased if a way could be found to suppress oxytocin in people who are predisposed to violence.

The research, published in the journal Social Psychological and Personality Science, provides some intriguing clues into the biological basis of the propensity for interpersonal violence.

DeWall and his colleagues note that oxytocin has been linked to “relationship maintenance.” In its benign form, that means inspiring behaviors that cement emotional closeness.

But they add that, for some people, preserving a romantic relationship involves physical and emotional abuse—actions aimed at intimidating one’s partner and preventing him or her from leaving. It turns out oxytocin can increase one’s inclination to engage in that kind of behavior as well.

Their study featured 93 undergraduates (47 men and 46 women). By random selection, each inhaled either 24 international units of oxytocin, or a similar amount of placebo. For the next 45 minutes, all participants performed a series of tasks, two of which (including giving a speech before an unsupportive audience) were designed to “increase stressful provocation.”

Their underlying aggressive tendencies were measured by having the students respond to two statements: “Given enough provocation right now, I might hit another person” and “If I had to resort to violence to protect my rights, I would right now.” They rated each on a one-to-seven scale (“extremely uncharacteristic of me” to “extremely characteristic of me.”)

They then reported, on a one-to-five scale, how likely they would be to engage in specific violent acts toward their current romantic partner (or their most recent partner if they were not in a relationship). These included “twist my partner’s arm or hair,” “push or shove my partner,” and “slap my partner.”

The results: Oxytocin increased participants’ inclination to engage in violence, but only among those “predisposed toward physical aggression.” It had no effect on those who lacked that underlying bent.

So for most people, a boost of oxytocin “signals a need to keep their partners close.” But for some, that signal inspires “behaviors designed to dominate their partners so that they do not flee the relationship.”

“Because physical aggression is a key part of their interpersonal repertoire,” the researchers write, “oxytocin may increase such behaviors.”

This raises the intriguing possibility that domestic violence could be decreased if a way could be found to suppress oxytocin in people who are predisposed to violence. It also provides new evidence that the initial view of the hormone as a uniformly positive force is way off-base.

Yes, oxytocin does inspire bonding. But not all bonds, and not all ways of preserving them, are healthy.