Caffeine improves the effectiveness of over-the-counter pain relieving drugs by a small margin according to a new evidence review in The Cochrane Library.
Caffeine, the same stimulant present in coffee, tea, sodas, and chocolate, is a common ingredient added to many analgesic formulations sold in Australian pharmacies.
The review set out to examine whether caffeine actually improves the pain-relieving effects of such medicines.
The authors identified 19 double-blind studies, with 7238 participants, that compared a single dose of analgesic plus caffeine with the same dose of the analgesic alone in the treatment of acute pain.
Most studies used paracetamol or ibuprofen, with 100 mg to 130 mg caffeine, and the most common pain conditions studied were menstrual period pain, postoperative dental pain, postpartum pain, and headache.
The review found that adding caffeine, at a dose equivalent to a mug of coffee, to a standard dose of common analgesics such as paracetamol or ibuprofen increases the number of people with acute pain who will experience a good level of pain relief by 5% to 10%.
Specifically, an additional five to 10 percent of patients who took the caffeinated formulations said that they experienced at least 50 percent of the maximum possible pain relief over four to six hours, considered their treatment very good or excellent, or had headache relief after two hours.
The mechanism by which caffeine boosts painkillers & effectiveness is currently unknown.
The stimulant could have multiple effects, including getting other drugs into the bloodstream faster, raising their concentration by slowing their clearance from the bloodstream, directly affecting how nerves perceive pain, or even changing how people perceive pain by affecting their moods or emotions.
According to Steven P.Cohen, Associate Professor of Anesthesiology and Critical Care Medicine at the Johns Hopkins School of Medicine and Director of Pain Research at Walter Reed National Military Medical Center, doctors should choose carefully which patients receive caffeine along with their regular pain medicines.
Since the booster effect is small, he explains, patients taking strong painkillers for very painful conditions probably won';t benefit.
However, he says, the drug is a relatively harmless addition that might help patients with more minor conditions.
Caffeine is a really, really safe drug, so safe that we don't regulate it," he says.
Basically, its a very minimal risk and might be beneficial, depending on the patient.
Derry CJ, Derry S, Moore RA.
Caffeine as an analgesic adjuvant for acute pain in adults.
Cochrane Database of Systematic Reviews 2012, Issue 3.