This Is Why Molly Makes You Grind Your Teeth

This bizarre side effect of MDMA has some people walking around raves with pacifiers.

In June 2016, I was rolling at a club in Ibiza when a man with beautiful arms appeared on my left. “Can I bite you?” I asked him without thinking, then dug my teeth into his shoulder. We’re still together two years later, and biting’s not normally my thing, so I think I owe my relationship to the fact that MDMA causes uncontrollable jaw tension.

I would later learn that this side effect was so common, some people wear pacifiers to raves or, for a less noticeable way to avoid destroying their mouths, chew gum. But why is it that, along with the euphoria and decreased inhibitions, MDMA users have to deal with a side of tooth grinding, jaw clenching, and lip-chewing?


Bruxism—the scientific term for jaw-clenching and tooth-grinding—is an instinct many people have even when they’re not rolling, says Ronald Baise, dentist at 92 Dental, a practice in London. “Jaw clenching and tooth grinding is a reflex action caused by a discrepancy between one's perceived ‘optimal bite’ and their actual bite,” he explains. “Our teeth want to be in a certain contact with other teeth to protect the soft part of our mouths from damage.” Since MDMA is a stimulant, it heightens all our evolutionary reflexes, this one included, Baise explains.

MDMA also floods our brains with the feel-good chemical serotonin, which in turn decreases production of the neurotransmitter dopamine by stimulating a group of neurons called the raphe nuclei, says Enzo Tagliazucchi, a neuroscientist studying psychedelics at the University of Buenos Aires and the Brain and Spine Institute in Paris. Typically, dopamine in the midbrain’s substantia nigra feeds into the basal ganglia, a group of neuron clusters involved in motor coordination. With our dopamine depleted, we have less self-control over our reflexes. This is also why Parkinson’s patients, who suffer from dopamine deficiency, experience involuntary movements, Tagliazucchi adds.

It could also be due to serotonin’s inhibition of dopamine production that SSRIs—antidepressants that stop your neurons from reabsorbing serotonin, so more hangs around in your brain—sometimes cause jaw grinding, Tagliazucchi tells me.


Other psychoactive substances that sometimes get mixed into ecstasy or molly can compound its effect on the jaw, he adds. Stimulants like amphetamine, cocaine, and caffeine can do this by increasing muscle tension, and other substances like MDA and MMDA can affect the jaw in a similar way to MDMA.

While people’s main concern about MDMA-induced bruxism is usually that it’ll make their drug use obvious, there are also some medical risks. It’s possible for people on MDMA to hyperextend their jaws or open them past the point of comfort, which can lead them to get dislocated, says Brijesh Chandwani, clinical associate professor at the Tufts University School of Dental Medicine. Several Redditors can attest to the fact that chipped teeth aren’t out of the question either. There’s even a case study in the British Dental Journal of an 18-year-old who bit off a chunk of her lower lip on MDMA.

Sometimes, bruxism triggered by MDMA can become chronic, Chandwani adds. He had one patient who grinded her teeth for two years after using MDMA just once. Some people find that taking magnesium supplements helps them avoid bruxism, since magnesium increases dopamine levels in the brain, Baise says. And as always, watch your dose because the more you take, the more susceptible you are to every side effect.

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