Health Team

Marijuana use increases pain after surgery, requires more anesthesia, study finds

If you think smoking or ingesting weed helps control pain of all types, think again.

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Sandee LaMotte
CNN — If you think smoking or ingesting weed helps control pain of all types, think again.

Using marijuana before entering the hospital for a surgical procedure can make your pain during recovery significantly worse, according to research presented Monday.

"There is some evidence that cannabis may be beneficial for chronic and nerve pain. However, early research suggests that this is not the case for acute pain such as for surgery of a broken leg," said lead author Dr. Ian Holmen, an anesthesiology resident at the University of Colorado Hospital in Aurora, in a statement.

Besides an increase in acute pain, people who used weed before surgery also needed more anesthesia during surgery -- undergoing anesthesia can be risky for some people, such as the elderly or those with chronic illnesses such as diabetes -- and used more opioids during recovery.

"This study shows that it is important for patients to tell their physician anesthesiologist if they have used cannabis products prior to surgery to ensure they receive the best anesthesia and pain control possible, including the use of non-opioid alternatives," Holmen said. The research was presented at the annual meeting of the American Society of Anesthesiologists on Monday.

The study compared patients undergoing surgery for a broken leg who said they had used cannabis before the operation to those who said they had not. The type and method of use of marijuana was not known; nor was how frequently the patient used weed.

Those who reported using weed received 58% more opioids per day while in the hospital, reported greater levels of pain on a scale of 1 to 10, and required an additional 12.4 milliliters of anesthesia during surgery than those who did not use pot.

During surgery, an anesthesiologist will up the dosage if they observe "involuntary body movements, increased heart rate, high blood pressure or increased rate of breathing," the study found -- all signals of greater pain levels.

The findings add to existing research, which has found patients who use weed have more surgery-related pain, which is also the case for opioid users.

"We now understand patients who chronically use opioids prior to surgery often have exaggerated pain responses and need increased pain medication after surgery because they have an increased tolerance," Holmen said.

"We speculate that cannabis use may cause a similar effect, but we need more research to determine if this is the case."

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