Swearing when you hit your thumb or stub a toe may help to lessen the pain.

In the Aug. 5 issue of the journal NeuroReport, British researchers report that they found some volunteers were better able to withstand the pain from plunging their hand in a tub of ice water for as long as possible when they are asked to repeat a swear word of their choice compared with an inoffensive word.

Since swearing often has a "catastrophizing" or exaggerating effect, psychology researcher Richard Stephens of Keele University, North Midlands, and his colleagues expected the bad words would actually decrease pain tolerance.

"Swearing has been around for centuries and is an almost universal human linguistic phenomenon," Richards said in a release.

"It taps into emotional brain centres and appears to arise in the right brain, whereas most language production occurs in the left cerebral hemisphere of the brain. Our research shows one potential reason why swearing developed and why it persists."

In contrast to their expectations, volunteers were able to keep their hands in the ice water for longer when repeating the swear word, showing a link between swearing and an increase in pain tolerance.

During the foul-mouthed test, volunteers kept their hands submerged for about 40 seconds longer and reported feeling less anxiety and less fear of the pain, the researchers found.

Fight-or-flight response?

The researchers suspect swearing helped to distract participants from their pain.

Cursers showed increased heart rates, which suggest the profanities might trigger a natural "fight-or-flight" response of downplaying "feebleness in favour of a more pain-tolerant machismo," the researchers said.

Previous studies suggest swearing can provide an emotional release, while in other situations it can signal aggression.

The results show swearing triggers both a physical and an emotional response, which could help explain why cursing developed and still exists.

In the study, women's heart rates increased more than men's.

Swearing also did not increase pain tolerance in men with a tendency to catastrophize, the researchers said.

"The observed pain-lessening [hypoalgesic] effect may occur because swearing induces a fight-or-flight response and nullifies the link between fear of pain and pain perception," they concluded.