Surprising Side Effects of Too Much Marijuana, Say Experts

The days of Reefer Madness hysteria seem long behind us as more and more states legalize recreational marijuana. (Last week, one of the most conservative Supreme Court justices, Clarence Thomas, said he believed federal anti-marijuana laws might no longer be necessary.) Although pot is no longer considered the mania-inducing menace of years past, it's not harm free—like many milder, legal substances such as caffeine, pot can cause negative side effects if you use too much. Here are some potential physical reactions that may surprise you. Read on—and to ensure your health and the health of others, don't miss these Sure Signs You May Have Already Had COVID.

1. Anxiety

Marijuana has a long reputation as a relaxant. But taking too much of it can have the opposite effect, causing anxiety, paranoia, and even panic attacks, says the Centers for Disease Control and Prevention. "A fatal overdose is unlikely, but that doesn't mean marijuana is harmless," the CDC warns.

Some heavy marijuana users experience severe nausea, vomiting, and pain after using cannabis. It's called cannabinoid hyperemesis syndrome, or CHS, and the symptoms tend not to respond to drug treatment. Experts estimate 2.7 million Americans experience the condition, which is frequently misdiagnosed as a psychiatric problem or GI issue before the true culprit is discovered. (Last year, it was the subject of the Washington Post's "Medical Mysteries" column.) "CHS went from being something we didn't know about and never talked about to a very common problem over the last five years," Dr. Eric Lavonas, a spokesman for the American College of Emergency Physicians, told the New York Times. It has a simple cure: Stop smoking pot.

3. Trouble Breathing

Just like cigarettes, marijuana joints require you to inhale smoke, which can lead to breathing issues. "Marijuana smoke irritates the lungs, and people who smoke marijuana frequently can have the same breathing problems as those who smoke tobacco," says the National Institute on Drug Abuse (NIDA). "These problems include daily cough and phlegm, more frequent lung illness, and a higher risk of lung infections." However, the agency notes, smoking pot has not been found to raise lung cancer risk.

4. Rapid Heart Rate

Also surprising for a renowned chill-out drug: Smoking marijuana can increase blood pressure, says the Mayo Clinic. "Marijuana raises heart rate for up to three hours after smoking," says NIDA. "This effect may increase the chance of heart attack. Older people and those with heart problems may be at higher risk."

5. Mental Health Issues

"If you have a mental health condition, use marijuana with caution," advises the Mayo Clinic. "Marijuana use might worsen manic symptoms in people who have bipolar disorder. If used frequently, marijuana might increase the risk of depression or worsen depression symptoms."