Heavy users of marijuana might face an increased risk of bipolar disorder and depression, a new study suggests.

The analysis of more than 6.6 million Danish individuals found that having cannabis use disorder doubled or even tripled the odds for most forms of depression or bipolar disorder. When it came to bipolar disorder in particular, "cannabis use disorder was associated with higher r...

A subset of people may be at high risk for both psychiatric disorders and for using marijuana, based on their genetics, according to a new study.

Researchers from the University of Oslo in Norway have found that some of the genetic variants associated with cannabis use are also linked to psychiatric disorders.

“These findings are important as they show that the complex links betw...

Teens who use electronic cigarettes are significantly more likely than non-vapers to binge-drink and use cannabis, new research finds.

Surveys of teens ages 13 to 18 revealed that vapers were 20 times more likely to use marijuana than teens who used no nicotine products. And those who vaped in the previous month were six times more likely to have had multiple binge-drinking episodes ...

As recreational marijuana use rises, some dispensaries are recommending it as a remedy for morning sickness, but new research warns that using it during pregnancy may significantly affect fetal growth.

While fetal exposure to cannabis in early pregnancy can reduce birth weight, those effects can become more severe if use continues throughout the pregnancy, according to researchers at Cen...

Smoking cigarettes has long been linked to peripheral artery disease (PAD), a condition where the buildup of plaque narrows arteries and limits blood flow to the legs or arms.

Now, a new study suggests that marijuana may have a similar impact, after finding that users had three times the risk of developing PAD.

Although the study is preliminary and doesn't determine whether th...

Marijuana appears to significantly increase young men's risk of developing schizophrenia, a new study suggests.

Up to 30% of schizophrenia cases among men aged 21 to 30 are related to heavy and problematic use of marijuana, according to the findings.

The researchers also found a tripled overall risk of schizophrenia linked to cannabis use in young men compared to women: Around 15% o...

Medical marijuana can safely reduce cancer pain, and is apparently so effective that patients wind up taking lower amounts of opioids and other pain meds, a new study reports.

Weed produced clinically significant reductions in cancer patients' worst pain, average pain and overall pain severity, said senior researcher ...

Suspected suicide attempts linked to marijuana overdoses have been steadily increasing over the past decade, a new study reports.

National Poison Data System records show a 17% yearly increase in reports of suicidal people who have been poisoned by using too much cannabis, said co-researcher Tracy Klein

Marijuana legalization in the United States appears to be driving an increase in car crash deaths due to a jump in "intoxicated driving," researchers say.

In 4 out of 7 states that legalized recreational cannabis, deaths from car crashes rose 10%, according to the University of Illinois Chicago study. On a brighter note, suicide and opioid overdose deaths declined in the states that legal...

With cannabis poisoning soaring among U.S. children, an expert from Children's Hospital Los Angeles offers tips for keeping kids safe from so-called “edibles.”

“The best way to keep your kids safe from marijuana edibles is not to have them in your home,” Dr. Colleen Kraft, an attending physician in th...

For decades, people turned to cigarettes in times of stress. Now, a preliminary study hints that young people are using vaping in the same way.

The study, of nearly 2,000 U.S. teenagers and young adults, found that those who vaped nicotine or marijuana were more likely to report anxiety, depression or suicidal thoughts. In fact, a majority of vapers said they'd suffered anxiety or depress...

New research suggests that smoking weed is far from benign: Toking every day might raise your odds of heart disease.

The increased risk is not insignificant. Daily marijuana users are about one-third more likely to develop coronary artery disease, compared with people who have never used the drug, researchers say.

Marijuana is becoming more widely available and its link with heart ...

There's a popular notion that cannabidiol (CBD) can take the edge off the less pleasant effects of marijuana. But a new study suggests that, when it comes to edibles, the opposite is true.

Researchers found that when they gave study volunteers a batch of pot brownies, the effects were as one...

It's not clear why, but youths in U.S. states where medical marijuana is legal report more vaping of cannabis than their peers in states where weed is legal for all adults or it is completely illegal.

New research fo...

New research links cannabis use in the first trimester of pregnancy to poor outcomes, closely related to functioning of the placenta.

This is important information given that more U.S. states are legalizing marijuana for recreational use, researchers said. The study findings were presented Thursday at a meeting of the Society for Maternal-Fetal Medicine, in San Francisco and online.

Laws bar advertising cannabis to teens, but that doesn't mean they always work.

In a new survey, researchers found that teens still see a lot of positive cannabis messages through social media posts.

These messages influenced their intentions a...

Living in a U.S. state where recreational weed is legal does not appear to increase the average adult's risk of succumbing to “reefer madness,” a new study of twins has determined.

An adult living in a “legal” state is not more likely to develop any sort of substance abuse disorder than their twin residing in a state where marijuana remains outlawed, researchers found.

They ...

The U.S. Food and Drug Administration said Thursday it can't regulate CBD supplements because there isn't enough evidence on their safety. The agency also called on Congress to create new rules for what has become a burgeoning industry.

"The use of CBD raises various safety concerns, especially with long-term use," FDA Deputy Commissioner