What medical and legal issues come up with marijuana use?

Q. I heard that marijuana helps glaucoma. I’d like to try it, but won’t I get in trouble?

Marijuana can help your glaucoma, and it could get you in trouble because there are legal restrictions upon its use. If you are interested in trying medical marijuana for your glaucoma, discuss this treatment with your doctor. (I could write an entire column on the marijuana laws, but I’ll stick to the health issues.)

Marijuana refers to the parts of the Cannabis sativa plant, which has been used for medicinal purposes for more than 4,800 years. Doctors in ancient China, Greece and Persia used it as a pain reliever, and for gastrointestinal disorders and insomnia.

Cannabis as a medicine was common throughout most of the world in the 1800s. It was used as the primary pain reliever until the invention of aspirin.

Marijuana contains at least 60 chemicals called cannabinoids. THC is the main component responsible for marijuana’s mind-altering effect. Marinol (dronabinol), a prescription drug taken by oral capsule, is a man-made version of THC

One of THC’s medical uses is for the treatment of nausea. It can alleviate mild to moderate nausea caused by cancer chemotherapy and help reduce nausea and weight loss in people with AIDS.

Older people, especially those with no marijuana experience, may not tolerate THC’s mind-altering side effects as well as young people. Doctors generally prescribe several kinds of newer anti-nausea drugs with fewer side effects before resorting to Marinol.

Glaucoma increases pressure in the eyeball, which can lead to vision loss. Smoking marijuana reduces pressure in the eyes. Your doctor can prescribe other medications to treat glaucoma, but these can lose their effectiveness over time.

Researchers are trying to develop new medications based on cannabis to treat pain. THC may work as well in treating cancer pain as codeine. A recent study found that cannabinoids significantly reduced pain in people with multiple sclerosis, a disease of the nervous system.

Along with the legal implications of smoking marijuana are the health problems such as memory impairment, loss of coordination and the potential for withdrawal symptoms and hallucinations. And, inhaling marijuana smoke exposes you to substances that may cause cancer.

One study has indicated that the risk of heart attack more than quadruples in the first hour after smoking marijuana. The researchers suggest that a heart attack might be caused by marijuana’s effects on blood pressure, heart rate and the capacity of blood to carry oxygen.