By Serena Gordon
"People who have persistent pain problems need to know that a potential side effect of long-term opioid use may be erectile dysfunction," said lead study author Dr. Richard Deyo, a clinical investigator for the Kaiser Permanente Center for Health Research in Portland, Ore. "This is not a well-known potential side effect among patients, and it should be considered when thinking about treatment."
Deyo also noted, however, that "the nature of this study as an observational study limits our ability to make a causal [cause-and-effect] inference. Opioid use and erectile dysfunction seem to go together, but we have to be cautious about saying one causes the other."
Results of the study were published in the May issue of the journal Spine.
More than 4 million people use opioids on a regular basis, Deyo said. Commonly prescribed opioids include hydrocodone, oxycodone and morphine. In this study, use of opioids was considered long-term if patients used them for more than 120 days, or more than 90 days if more than 10 prescriptions were filled for the drugs.
The study included data on about 11,000 men who had back pain. In that group, more than 900 received medications for erectile dysfunction or testosterone replacement. Those who were given prescriptions for erectile dysfunction medications or testosterone were older than those who didn't get such prescriptions. They also were more likely to have depression and other health conditions.
And those who were taking erectile dysfunction medications or testosterone tended to be smokers or users of sedative medications, according to the study.
Age was the most significant factor in getting a prescription for erectile dysfunction, according to the study. Men between the ages of 60 and 69 were 14 times more likely to receive a prescription for an erectile dysfunction medication than men who were between 18 and 29.
After adjusting the data to account for other possible factors, including age, the researchers found that men who took opioid pain medications for long periods were about 50 percent more likely to take erectile dysfunction medications or testosterone replacement therapy.
Dr. Daniel Shoskes, a professor of urology at the Cleveland Clinic's Glickman Urological and Kidney Institute, said the study doesn't prove that the pain medications cause the erectile dysfunction.
"A direct association between long-term opioid use and [erectile dysfunction] has not been clearly defined," said Shoskes, who was not involved in the study. "The reason these men were having [erectile dysfunction] could be related to the pain or the things that are causing the pain. You can't conclude from this study that opioid use causes [erectile dysfunction]."
Study author Deyo said there's evidence that men who stop taking opioids after using them for a short time will see an improvement in erectile dysfunction, but he said it's not clear if the same is true after long-term use.
Deyo added that opioids can be effective for short-term use, but there's "growing evidence that long-term opioid use may not be effective for chronic pain. The body compensates for taking long-term pain medications, and changes in the brain and spinal cord may make people more sensitive over time."
Effective alternatives include a tailored exercise program and cognitive behavioral therapy designed to help reduce people's fear of pain, Deyo said.
Shoskes said other factors that contribute to erectile dysfunction include diabetes, heart disease, peripheral vascular disease and alcohol use. He said this study may prompt doctors who treat men with chronic pain to ask about erectile dysfunction, although he said it's not clear from this study whether the erectile medications were helpful for these men.