Maybe it’s because I was born a couple of months after Woodstock and wasn’t around when marijuana was as common as iPods are today, but I’m constantly amazed that after all these years–and all the wars on drugs and all the public-service announcements–nearly 15 million Americans still use marijuana at least once a month. California and 10 other states have already decriminalized marijuana for medical use. Now two of those states–Colorado and Nevada–are considering ballot initiatives that would legalize up to an ounce of pot for personal use by people 21 and older, whether or not there is a medical need. What do voters need to know before going to the polls? The first is that marijuana isn’t really very good for you. True, there are health benefits for some patients. Several recent studies, including a new one from the Scripps Research Institute, show that THC, the chemical in marijuana responsible for the high, can help slow the progress of Alzheimer’s disease. Other studies have shown THC to be a very effective antinausea treatment for people–cancer patients undergoing chemotherapy, for example–for whom conventional medications aren’t working. And medical cannabis has shown promise relieving pain in patients with multiple sclerosis and reducing intraocular pressure in glaucoma patients. See Sanjay Gupta’s column Fit Nation. But I suspect that most of the people eager to vote yes on the new ballot measures aren’t suffering from glaucoma, Alzheimer’s or chemo-induced nausea. Many of them just want to get stoned legally. That’s why I, like many other doctors, am unimpressed with the proposed legislation, which would legalize marijuana irrespective of any medical condition. Why do I care? As Dr. Nora Volkow, director of the National Institute on Drug Abuse, puts it, “Numerous deleterious health consequences are associated with [marijuana’s] short- and long-term use, including the possibility of becoming addicted.” What are other health consequences? Frequent marijuana use can seriously affect your short-term memory. It can impair your cognitive ability and lead to long-lasting depression or anxiety. While many people smoke marijuana to relax, it can have the opposite effect on frequent users. And smoking anything, whether it’s tobacco or marijuana, can seriously damage your lung tissue. The Nevada and Colorado marijuana initiatives have gained support from unlikely places. More than 33 religious leaders in Nevada have endorsed the measure, arguing that permissive legalization, accompanied by stringent regulations and penalties, can cut down on illegal drug trafficking and make communities safer. Perhaps. But I’m here to tell you, as a doctor, that despite all the talk about the medical benefits of marijuana, smoking the stuff is not going to do your health any good. And if you get high before climbing behind the wheel of a car, you will be putting yourself and those around you in danger. Sanjay Gupta is a neurosurgeon. Check out his podcast at cnn.com/health See TIME’s pictures of the week.
