Dr. Gupta Backs Medical Marijuana

August 9, 2013

News Review From Harvard Medical School -- Dr. Gupta Backs Medical Marijuana

A prominent TV doctor says he was wrong about medical marijuana. Sanjay Gupta, M.D., will explain his views in a documentary Sunday on CNN. He wrote about them in an article published August 8 on CNN.com. Dr. Gupta, a neurosurgeon, is the network's chief medical correspondent. In the past, he has opposed medical marijuana, now legal in 20 states. But he recently changed his mind after looking more closely at the evidence. Dr. Gupta cited specific people he has learned about for whom marijuana is the only drug that helps to stop seizures or pain. Marijuana is a Schedule I drug under U.S law. This means it is likely to be abused and has no medical use. Dr. Gupta disputed both of those statements. He said about 10% of marijuana users become addicted. Those are less than half the rates for other illegal drugs or tobacco. He said marijuana may especially help neuropathic pain, a tingling type that is hard to treat. People usually get opioid drugs for this type of pain. However, they can be addictive. Overdose can be fatal. Dr. Gupta said he did not support marijuana use for children or teens because of evidence that it can harm the developing brain.

By Mary Pickett, M.D.
Harvard Medical School

What Is the Doctor's Reaction?

CNN's popular doctor-reporter Sanjay Gupta is hosting a documentary this week. He is talking about medical uses for marijuana. In a preview article, Gupta describes several people with pain or epilepsy. For them, the benefits of marijuana are larger than the risks. He wants to make this drug accessible to patients who could use it for medical reasons.

I can agree that a small group of unusually sick patients can probably benefit from marijuana. But Gupta goes on to say more.

Gupta says he has tried marijuana. And regarding his children he says, "I wouldn't permit marijuana until they are adults. If they are adamant about trying marijuana, I will urge them to wait until they're in their mid-20s when their brains are fully developed." To me, this sounds like an endorsement of recreational, not just medical, marijuana use.

Like Gupta, I am a doctor who has kept a close eye on the evidence about risks and potential benefits of marijuana. But I do not recommend it as a safe drug for recreational use, particularly when it is used often.

For a small number of people, the benefits are greater than the risks. This does not mean that marijuana is a "safe" drug. And it does not mean that benefits outweigh the risks for people who are well.  

What Changes Can I Make Now?

Understand the risks of marijuana. Most people have a distorted view about its safety. Known risks from marijuana use include:

• Psychiatric effects: Marijuana changes the brain. It has been linked with substantial increases in the risk of schizophrenia and unexplained psychotic symptoms later in life, even if you no longer use the drug. In a study of nearly 4,000 adults, people who first used marijuana before age 16 were twice as likely as non-users to report psychotic symptoms when they were 21.  They were 3 times as likely to have hallucinations -- seeing or hearing things that were not real. They were 4 times as likely to have delusions -- beliefs that persist despite clear evidence they are not true.

• Addiction: Marijuana is a gateway drug for addictions. You can become addicted to marijuana. It can lead to heavier drug addictions.

• Long-term memory and attention skills: Numerous studies have raised concerns about memory skills in marijuana users. Young adults who have used marijuana an average of 10 years have poorer brain function than short term users do, even after they stop smoking the drug.

• Stroke: A small study presented at the 2013 International Stroke Conference suggests that marijuana can trigger stroke in young adults. The study included 160 people between ages 18 and 55 who were being treated in a hospital for a stroke and agreed to have urine drug testing. They were compared with a similar group of people who did not have strokes. Twice as many people in the stroke group had traces of marijuana in their urine.

• Lung disease: Smoking marijuana cigarettes exposes the lungs to many pollutants, much like smoking nicotine cigarettes. Habitual marijuana use can cause airway inflammation, asthma and other lung problems.

• Heart attack: Risk is higher right after you smoke marijuana.

• Vomiting: Some long-term users say they are using marijuana to treat frequent nausea. But cyclic vomiting can also come from marijuana use.

• Infertility and lower sex drive: In men, marijuana may affect the function and quantity of sperm. It can reduce testosterone levels and sex drive, and cause impotence. In women, period cycles can become shorter and fertility can be reduced.

• Effects in pregnancy: Repeated marijuana use in pregnancy is a suspected cause of reduced birth weight of babies.

What Can I Expect Looking to the Future?

Marijuana is now legal in 2 states. Medical marijuana has become acceptable in a larger number of states. In 2008, regulators in the United Kingdom changed marijuana to a "Class B" drug under the law. This category is reserved for harmful drugs. It is similar to a Schedule II controlled substance under U.S. law.

Many advocates of medical marijuana would like to see this drug changed to a Schedule II, III or IV controlled substance, so that doctors can prescribe it.  If this occurs someday, it still does not mean that use is safe. It only means that in the context of certain medical illnesses, benefit may be greater than risk.

Be informed about marijuana -- there are ways it can harm you.