Why Popular Painkiller Could Be Making Headaches Worse
Taking the popular painkiller codeine too often could make a headache worse, according to a new study.
Researchers found the more of the over the counter medication people take the worse their pain gets, a particular problem for chronic sufferers.
A study that compared the effect of codeine and morphine, both opioid drugs, for the first time found the former provided much less pain relief, but resulted in the same level of increased sensitivity to pain.
Headache specialist Professor Paul Rolan, of the Royal Adelaide Hospital in Australia, said codeine has been widely used as pain relief for more than 100 years, but its effectiveness has not been laboratory tested in this way before.
He said: "In the clinical setting, patients have complained their headaches became worse after using regular codeine, not better.
"Codeine use is not controlled in the same way as morphine, and as it is the most widely used strong pain reliever medication in the world, we thought it was about time we looked into how effective it really is."
Jacinta Johnson, a University of Adelaide PhD student, said a major issue for users of opioid drugs is the more you take, the more it can increase your sensitivity to pain, so you may never get the level of relief you need.
Ms Johnson said: "In the long term it has the effect of worsening the problem rather than making it better.
"We think that this is a particular problem in headache patients, who seem more sensitive to this effect.
"Both codeine and morphine are opioids but codeine is a kind of 'Trojan horse' drug - 10 per cent of it is converted to morphine, which is how it helps to provide pain relief.
"However, despite not offering the same level of pain relief, we found that codeine increased pain sensitivity just as much as morphine."
While more research is needed, the findings suggest a potential problem for anyone suffering from chronic pain who needs ongoing medication.
Prof Rolan added: "People who take codeine every now and then should have nothing to worry about, but heavy and ongoing codeine use could be detrimental for those patients who have chronic pain and headache.
"This can be a very difficult issue for many people experiencing pain, and it creates difficulties for clinicians who are trying to find strategies to improve people's pain."
Ms Johnson presented the research at the 2013 International Headache Congress in Boston, and her work is also featured in Neurology Reviews.
A clinical trial testing a new approach to treating codeine related headache is now being run by Professor Rolan.
telegraph.co.uk
