Researchers from the Diamond Headache Clinic in Chicago have found that the caffeine present in a cup of tea or coffee might be able to relieve "tension headaches" in consumers.

Tension headaches are characterised by constant, dull pain that can last for days and is often accompanied by muscle tightness in the shoulders and neck.

The Diamond team found that caffeine tablets taken in isolation appeared to be as useful for sufferers as taking standard pain relief tablets, such as ibuprofen. A total of 58% of people studied said that the caffeine capsule was successful in alleviating the headache. This figure was the same in those taking ibuprofen only.

Caffeine is already added routinely to many painkilling medications, and when added to standard headache tablets, the Diamond team recorded that 70% of patients reported complete relief. Only 58% reported the same when taking standard tablets without caffeine.

Overall, however, the health benefits of caffeine are debateable. Some scientists claim that when consumed in large amounts it actually increases the number of headaches.