A young man and young woman light up cannabis cigarettes while sitting along a lakeShare on Pinterest
Some experts recommend people stop using cannabis at least several days before surgery. Ascent X Media/Getty Images
  • Researchers say people who use cannabis tend to experience more pain after surgery than people who don’t use the drug.
  • They add that cannabis users have a tendency to use more opioids after surgery.
  • Experts say cannabinoid receptors in the brain may overlap with opioid receptors.
  • They add that cannabis users may build up a tolerance for opioids, making those pain relievers less effective.

Cannabis is often touted for pain relief and some research supports that claim.

However, a new study finds that cannabis users may experience more pain, not less, after undergoing surgery.

The study was presented at the American Society of Anesthesiologists’ Anesthesiology 2022 annual meeting in New Orleans. The findings haven’t been published yet in a peer-reviewed journal.

In their study, researchers looked at more than 34,000 people who had elective surgery at Cleveland Clinic, including more than 1,600 cannabis users.

They reported that those who had used cannabis within 30 days of surgery experienced 14% more pain in the 24 hours after surgery. They said cannabis users also took 7% more opioid painkillers than non-users did.

The findings square with past research showing that up to 20 percent of cannabis users experience higher levels of post-surgical pain, Dr. Samer Narouze, the chairman of the Center for Pain Medicine at Western Reserve Hospital in Cuyahoga Falls, Ohio, and a member of the American Society of Anesthesiologists’ Committee on Pain Medicine, told Healthline.

The new study is more comprehensive than past research that also found associations between cannabis use, pain scores, and opioid consumption, said Dr. Elyad Ekrami, the lead author of the study and clinical research fellow of the Outcomes Research Department at Cleveland Clinic’s Anesthesiology Institute, in a press statement.

“Physicians should consider that patients using cannabis may have more pain and require slightly higher doses of opioids after surgery, emphasizing the need to continue exploring a multimodal approach to post-surgical pain control,” Ekrami said.

Narouze said that cannabinoid receptors often overlap with opioid receptors in the spine and brain. Both are involved in pain regulation.

He said that opens the door for cannabis users to develop a tolerance for opioid medications, thus limiting their effectiveness.

It also produces the possibility that cannabinoids — a less effective analgesic — could crowd out opioids at receptor sites.

Another factor could be what Narouze called the paradox of THC, the main psychoactive component of cannabis. At low doses, THC can reduce pain, but at high doses, it may amplify pain.

“Heavy users of cannabis are the ones who experience more pain after surgery, not the casual users,” said Narouze.

Dr. Kelly Johnson-Arbor, a medical toxicology physician and co-medical director at National Capital Poison Center in Washington, DC, said cannabis use before surgery should be carefully evaluated.

“Those who regularly use cannabis to help manage pain may have an increased tolerance when it comes to pain management supports,” she told Healthline. “This may or may not translate to experiencing more pain after surgery because cannabis use is only one of the many factors that affect how much pain you feel.”

“This is why it is very important for patients to be honest with their doctors about their use of cannabis. Not divulging your cannabis use habits to your doctors may lead to inadequate anesthesia or postoperative pain control,” Johnson-Arbor added.

One of the limitations of the new study is that it did not collect data from cannabis users on how much they used, whether they smoked the drug, or whether or not they abstained from use prior to surgery, said Narouze.

Narouze advised that cannabis users who smoke marijuana should abstain from doing so for at least two weeks before any elective surgical procedure.

Dr. Jacob Hascalovici, the chief medical officer for Clearing, a digital health platform serving people with chronic pain, said cannabis users should avoid using the drug for at least 72 hours prior to surgery.

“That gives the body a little time to adjust to not having cannabis, so patients aren’t hit with the possible impacts of being off cannabis right after waking up from surgery,” he told Healthline. “It also reduces the odds that using cannabis may complicate the surgery itself.”

Jordyn Mastrodomenico, the clinical director at the ChoicePoint addiction treatment program in Fair Lawn, New Jersey, told Healthline that the findings about cannabis are similar to what is known about the effect of smoking and nicotine consumption on pain relief.

“Patients who smoke have a different pain threshold and, keeping this in mind, physicians give higher doses of anesthetics and analgesics,” she said. “There is a possibility that patients previously taking cannabis have a low tolerance profile to pain since they are already taking a potent drug… Treating pain in a patient that has already been given a potent analgesic is tough.”

Narouze, whose background includes studying the analgesic effects of cannabinoids, cautioned against using the findings as a reason to limit cannabis users’ access to pain medication during post-surgical recovery.

“There have not been reports of any significant, bad interactions between giving opiates and using cannabis,” he noted.