WEDNESDAY, Oct. 7, 2015 (HealthDay News) -- Medical marijuana appears mostly safe for treating chronic pain, at least among people with some experience using the drug, a new study suggests.

People who used pot to ease their pain didn't have an increased risk of serious side effects, compared to people with pain who didn't use marijuana, a Canadian research team found.

But, medical marijuana users were more likely to have less-serious side effects, the study authors said. These side effects included headache, nausea, sleepiness and dizziness, the research revealed.

"In terms of a side effect profile, we felt the drug had a reasonably good safety profile, if you compare those effects to other medications," said study lead author Dr. Mark Ware. He is director of clinical research for the Alan Edwards Pain Management Unit at McGill University Health Center in Montreal.

Although this study focused on the safety of medical marijuana, Ware reported that participants also appeared to experience some pain relief through their use of the drug. The researchers also saw improvements in mood and quality of life in the marijuana users.

Findings from the study were reported online recently in the Journal of Pain.

The trial is the first and largest study of the long-term safety of medical marijuana use by patients in chronic pain, Ware said.

The researchers followed 215 adult patients with chronic pain who used medical pot for one year. The researchers compared the marijuana users to a control group of 216 chronic pain patients who didn't use medical marijuana. The study involved seven pain treatment centers across Canada.

The people using pot were given leaf marijuana containing 12.5 percent THC from hospital pharmacies, Ware said. THC is the chemical in marijuana that causes intoxication. People could use pot however they liked -- smoking it, eating it in food, or inhaling it from a vaporizing device.

There was no difference in serious side effects between the two groups, the researchers found.

Marijuana users did have a 73 percent increased risk of minor side effects, the study found.