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Marijuana and the Heart

For those in the Baby Boomer generation or older, annual physicals probably include questions about alcohol intake, tobacco use, diet, and exercise. Doctors usually explain that as people get older, their risk for heart attacks increases. But while all of these topics are commonly discussed, marijuana use rarely comes up—a serious omission for those who are at increased risk for heart attacks.

In March 2000, researchers from the Beth Israel-Deaconess Medical Center in Boston, MA, showed how marijuana use increases risk for heart attacks. In the first hour after smoking marijuana, that risk increases to nearly five times the normal risk level. After an hour or so, the risk level drops to twice the normal risk. Several hours later, a marijuana user's risk for having a heart attack resumes its normal level.

Many people may have never associated marijuana with heart attacks, especially with the prevailing concept of marijuana as a "mellowing" drug. The truth is that although energy levels decrease after smoking marijuana, blood pressure and heart rate actually increase. In fact, a marijuana smoker's heart rate can increase by about 40 beats per minute, double the normal rate. Blood pressure increases if the user is sedentary or lying down, but it drops drastically if the person stands up or becomes active. This fluctuating blood pressure results in dizziness.

Medical records presented by the researchers showed 3,882 heart attack victims (32 percent women) were questioned about the cause of their heart attacks. Nine of them had used marijuana within 1 hour prior to the attack, 37 had used marijuana within 24 hours prior to the attack. In addition, although adults are at the greatest risk for marijuana-induced heart attacks, there have been at least two reports of juveniles who suffered from heart attacks after smoking marijuana. People most at risk are those with coronary disease, which in many cases can be undetected.

It's not yet clear why marijuana causes risk to the heart. It could be THC (the active ingredient in marijuana), the carbon monoxide, or any of the other components of the drug (although we know that one marijuana joint has four times as many toxins and carcinogens as a tobacco cigarette). If the marijuana is laced with cocaine, speed, LSD, or PCP, these added chemicals could have a greater impact on the heart.

During the month of February, when we celebrate both American Heart Month and Valentine's Day, it is fitting to note that not only does marijuana use physically affect users' hearts, it affects the emotional hearts of those around them by causing strain and distress in relationships.