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Letting loose with a satisfying string of expletives can significantly reduce physical pain, research has shown. But according to a new study, it doesn’t work as well if you make a habit of cursing frequently.

In a previous study, psychologist Richard Stephens at Keele University in the U.K. and colleagues found that people who were asked to dunk their hand in ice-cold water were better able to tolerate the pain — and they left their hands in the buckets for a full 40 seconds longer — if they were allowed to swear, compared with people who were asked to utter a non-curse word.

In the new study, Stephens repeated the previous experiment, asking 71 college students to submerge their hands in freezing water for as long as they could bear it. One group was asked to repeat a swear word of their choice — one they might use if they banged their head accidentally, for instance — while their hands were in the water. The other group was asked to repeat a control word they might use to describe a table. Then, both groups repeated the task using the word they hadn’t previously tried.

The researchers found that 73% of the participants kept their hands under water longer while swearing, replicating the original finding. On average, the swearers lasted 31 seconds longer in the cold hand plunge.

MORE: How Swearing Helps Kill Pain

Interestingly, however, the more frequently participants reported swearing during the course of their daily lives, the less effective cursing was at killing their pain and the shorter their endurance time in the cold water test.

It seems that swearing may help relieve pain by activating the brain’s endogenous opioids, the natural pain-relieving chemicals whose effects on the brain are similar to pain drugs like morphine and oxycodone. As with opioid drugs, repeated swearing may increase people’s tolerance to their effects, and cause them to need higher “doses” of cursing to achieve the same effect. In some sense, people may become addicted to — or at least physically dependent on — cursing.

The authors note that people who frequently express their anger verbally tend to be more sensitive to both acute and chronic pain. Indeed, research has found that these high “trait anger out” individuals also have a higher threshold for triggering endogenous opioid action in the brain. In other words, unless these people vigorously express their anger verbally, they feel more pain.

Although the current study didn’t look at people who have this temperament, it’s possible that those who tend to swear or express their anger frequently are trying to relieve their pain and irritability. They could become more outwardly angry over time, in order to chase opioid pain relief, which they increasingly become more tolerant to. Such individuals may also be especially susceptible to opioid addiction, and if they become addicted, they may be good candidates for long-term maintenance on the drugs to relieve this pre-existing opioid system dysfunction.

MORE: Why Crossing Your Arms Can Cut the Hurt

For everyone else, using swear words sparingly, and only for the choice pain that really requires them, may help maximize their pain-relieving effect.

The study was published in the Journal of Pain.

Maia Szalavitz is a health writer at TIME.com. Find her on Twitter at @maiasz. You can also continue the discussion on TIME Healthland’s Facebook page and on Twitter at @TIMEHealthland.