Adding caffeine, at a dose equivalent to a mug of coffee to a standard dose of common analgesics, increases the number of people with acute pain who will experience a good level of pain relief, according to a Cochrane review by Oxford University.
The researchers said caffeine was commonly used as a component in analgesic preparations available from pharmacies without a prescription but until now there had been little evidence to support the practice.
They reviewed 19 studies, involving around 7,000 patients, in which a single dose of analgesic plus caffeine was compared with the same dose of analgesic alone. In most of the studies 100-130mg caffeine was used as an adjuvant to paracetamol or ibuprofen.
Conditions treated included headache, post-dental pain, postoperative pain following childbirth, and menstrual period pain.
The researchers found a “small but statistically significant” benefit with caffeine used at doses of 100mg or more, which was not dependent on the pain condition or type of analgesic.
The authors said: “About 5% to 10% more participants achieve a good level of pain relief (at least 50% of the maximum) with the addition of caffeine, giving a number needed to treat of about 15.
“The addition of caffeine to a standard dose of commonly used analgesics provides a small but important increase in the proportion of participants who experience a good level of pain relief,” they said.