A cup of mint tea could be as effective as an aspirin for pain relief, according to scientists.

Research showed that the herb Hyptis crenata, known as Brazilian mint, reduced pain as much as a soluble form of the conventional painkiller. The study was tested on mice, which allowed researchers to rule out the placebo effect as an explanation for its success.

In Brazil, the plant has traditionally been used to treat mild pain, including headache, stomach ache, fevers and period pain. Until now it had never been subjected to scientific testing.

To mimic the traditional treatment, the researchers consulted Brazilian healers on how they prepared the tea. They made up a solution for mice containing the equivalent dosage of what most healers use for patients.

In the study, presented at the Second International Symposium on Medicinal and Nutraceutical Plants in New Delhi, the mint tea was compared with dissolved aspirin and pure water as a control. To determine how much pain relief each of the solutions provided, the scientists shone a hot infrared beam at the paws of the mice. When the mice felt pain they would instinctively lick their paw.

For both the aspirin and the mint tea, the mice took longer before they reacted to the beam, implying an increased tolerance. The two treatments were equally effective.

“We were really surprised by how well it worked,” said Graciela Rocha, of Newcastle University, who led the study. Ms Rocha, who is Brazilian, was given the tea as a child. “The taste isn’t what most people in the UK would recognise as mint, it is more like sage,” she said. “It’s not that nice really, but then medicine isn’t supposed to be nice, is it?”

The researchers plan to conduct controlled trials of the tea with people to establish a recommended medicinal dosage. They also plan to carry out further studies to determine which pharmacological compounds in the plant give it its painkilling properties.

Jenny Lancaster, a medical herbalist from the Scottish School of Herbal Medicine, said that salicylic acid, the active ingredient in aspirin, was found in willow bark, a native plant that has traditionally been used to treat arthritis. “It’s well known that plants contain thousands of pharmacologically active compounds,” she said.

The addictive quality of some of the most effective natural anaesthetics, such as opium, make them unsuitable as a medicine for mild pain. In Brazil, the mint tea is used almost exclusively in a medical context, suggesting that it does not have addictive properties.

About 50 per cent of prescription drugs are based on a molecule that occurs naturally in plants and 25 per cent are derived directly from flowering plants or modelled on plant molecules.

Although pharmaceutical companies carry out rigorous investigations into herbal extracts, the research often remains outside the public domain as large-scale clinical trials are normally undertaken only once a compound has been converted into a patentable drug.

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