Smokers may use more prescription opioid painkillers than non-smokers, according to a study from Norway.

The findings suggest, the researchers say, that doctors should ask patients about their smoking habits before prescribing opioids for pain that is not related to cancer.

While use of powerful opioid painkillers for non-cancer pain has risen sharply in many parts of the world, the use of these drugs is controversial, largely because of their addictive potential. Certain factors -- for example, a history of alcohol or drug abuse -- can increase a person's likelihood of abusing prescribed opioids.

There's also evidence that a person's smoking habits could influence their opioid use, Dr. Svetlana Skurtveit of the Norwegian Institute of Public Health in Oslo and her colleagues note in the Annals of Epidemiology.

To investigate, they looked at nearly 13,000 men and almost 16,000 women 30 to 75 years old who participated in health surveys between 2000 and 2002. None had been prescribed opioids at the time of study enrollment. During follow-up, lasting from 2004 to 2007, 1.5 percent of the study participants received 12 or more opioid prescriptions.

People who smoked at least 10 cigarettes a day at the study's outset were three times as likely as never-smokers to have been prescribed opiates at least 12 times during follow-up, the researchers found, while people who smoked one to nine cigarettes daily were at nearly double the risk of having multiple opioid prescriptions. The risk for people who used to smoke 10 or more cigarettes a day, but had quit, was roughly doubled.

It is important to note, the researchers say, that people who receive at least a dozen opioid prescriptions over the course of four years are not necessarily abusing the drugs or addicted to them.

Nonetheless, the current study suggests that being dependent on nicotine may predict more frequent use of opioids, they say.

There is ample evidence from experimental studies that nicotine and opioids modulate each other's effects, Skurtveit and her colleagues add, while smoking can also influence pain perception.

Based on their findings, they suggest that doctors might want to screen for smoking habits before starting pain treatment with opioids.