New research shows that while it led to a decline in hospitalizations for chronic pain, there were increases in traffic crashes, alcohol abuse and drug overdoses in the state. However, there was no significant increase in overall hospital admissions.
"We need to think carefully about the potential health effects of substantially enhancing the accessibility of cannabis, as has been done now in the majority of states," said study senior author Dr. Gregory Marcus, associate chief of cardiology for research at the University of California, San Francisco.
Colorado's legalization process offers "an extraordinary opportunity to investigate hospitalizations among millions of individuals in the presence of enhanced access," he added in a university news release.
"Our findings demonstrate several potential harmful effects that are relevant for physicians and policymakers, as well as for individuals considering cannabis use," Marcus noted.
In the study, the researchers analyzed more than 28 million hospital records two years before and two years after marijuana was legalized in Colorado.
Compared to other states, there was a slight overall increase in hospital admissions for cannabis abuse after legalization.
Also after legalization, there was a 5% decrease in hospital admissions for chronic pain, but a 10% increase in motor vehicle accidents and a 5% increase in alcohol abuse and overdoses that resulted in injury or death.
The study was published online May 15 in the BMJ Open journal.
The finding of fewer diagnoses of chronic pain after legalization are consistent with a 2017 National Academy of Science report that concluded there is substantial evidence that cannabis can reduce chronic pain, the researchers noted.
More than 117 million Americans (44.2%) have used cannabis in their lifetime, and more than 22 million said they'd used it within the past 30 days, according to the 2014 U.S. National Survey on Drug Use and Health.
Medical use of cannabis is legal in 28 states and the District of Columbia, and nine of those states have legalized it for recreational use.
"There has been a dearth of rigorous research regarding the actual health effects of cannabis consumption, particularly on the level of public health," Marcus said.
"These data demonstrate the need to caution strongly against driving while under the influence of any mind-altering substance, such as cannabis, and may suggest that efforts to combat addiction and abuse of other recreational drugs becomes even more important once cannabis has been legalized," he added.
