Older adults appear to be the fastest-growing group of new users of medical marijuana. A National Survey on Drug Use and Health found a 250 percent relative increase in cannabis use among those 65 and older from 2006 to 2013.

During the course of my career, patients have asked me to write an authorization letter so they can obtain medical marijuana. I assumed that every time a letter was requested, it was someone really seeking marijuana for recreational use, especially if they had a history of abusing alcohol, opiates or some other substance. My response was to “just say no,” particularly since marijuana is listed federally as a Schedule 1 drug (in the same category as heroin), which can be a prescribing deterrent for even the most caring physicians.

I am not the only one reluctant to authorize medical marijuana. I continually hear stories about oncologists and neurologists declining to write letters for medical marijuana use for their patients. I was taught throughout my medical career to base my prescribing on high-quality scientific studies. But what if good studies are nonexistent because of federal prohibition?

To address any underlying bias I might have, I sought out older adults who are using medical marijuana on a regular basis. Here is what I learned:

“Doug,” in his early 60s, has been using medical marijuana for a few years. He has had two different cancers for which he has undergone extensive surgeries and radiation therapy. “The radiation cooked me,” he said, and the resulting pain was far more severe than the pain from the tumors or from his surgeries. Doug did not do well with high doses of narcotics like OxyContin, so he turned to medical marijuana. He explained that marijuana comes in several different types: THC (tetrahydrocannabinol) is psychoactive and creates the euphoria that people prefer in recreational use. CBD (cannabidiol) is not psychoactive and is most useful for pain relief and reducing anxiety, nausea and muscle spasms.

Doug tried a variety of formulations, including cannabis oil under his tongue and various edibles, before settling on daily CBD gels that control his symptoms. He said he has had no adverse reaction to CBD and no mental impact, and can drink alcohol without significant worry.

“Linda,” also in her 60s, believes medical marijuana saved her life. When she was told that she had melanoma, her doctor at Stanford prescribed a year of chemotherapy. But the chemo drug caused severe nausea and loss of appetite, not helped by any prescription medication. Within six months, Linda had lost 60 pounds and was weighed a mere 100 pounds.

She realized her life was at stake whether she stopped the chemotherapy or continued, so in desperation she turned to marijuana to restore her appetite and alleviate her nausea. She found that edibles worked best for her because the effect lasted longer. Like many people who try medical marijuana, sufficient trial and error was required to find the right dose. Linda kept detailed notes, measured how much brownie she used each time, and took photos so she could judge what worked best for her. She ended up saving thousands of dollars from co-payments for anti-nausea medications, which had not worked. Her doctors were thrilled that she could complete her course of chemotherapy. Six years later, her cancer remains in remission.

“Sue,” 70, has been eating marijuana-laced brownies for three years to treat insomnia after prescription meds failed to help. She also suffers from arthritis and spinal stenosis, and the beneficial effects have been “amazing,” she said. She sleeps a sound seven hours every night and has much less pain. Sue uses the CBD type for insomnia because she did not enjoy the experience of hallucinating before bedtime or having vivid dreams. She also “vapes” medical cannabis periodically when she needs something for anxiety.

“Tom” suffers from muscle cramps, pain in his feet and legs, and peripheral neuropathy as a consequence of a chemotherapy drug he took to treat a malignancy in his bones. He was reluctant to smoke medical marijuana because of a history of bronchitis, so he has tried cannabis oil under his tongue and a variety of edibles. He uses some type of edible almost every night, which helps his sleep and neuropathy significantly. Tom has had no adverse reaction to medical cannabis, in contrast to the sleeping pills he took previously.

My conclusion?

Medical marijuana appears safe and has fewer adverse reactions than commonly prescribed medications. And to my knowledge, no deaths have been reported from marijuana use.

In addition to helping with the conditions described above, marijuana reportedly can help with a variety of other disorders, such as chronic pain, peripheral neuropathy due to diabetes, Parkinson’s disease, epilepsy, inflammatory bowel disease (like Crohn’s), and multiple sclerosis.

Though marijuana can be consumed in many ways, because doses are not standardized at this time, experimentation may be required to find out what works best.

There is a lot to like about medical marijuana, but there are some risks. Marijuana use may increase the likeliness of bleeding in those who use anticoagulants, aspirin or nonsteroidal anti-inflammatory drugs such as Motrin or Aleve. It may affect blood sugar levels or blood pressure, and can cause drowsiness, particularly if combined with prescription sleeping pills, anti-depressants or alcohol (which could then increase the risk of falling or injury). And there could be psychological addiction with prolonged use.

I am no longer as fearful about recommending medical marijuana: In the future, if a patient with a legitimate medical problem comes to me requesting it, I will not hesitate to write a letter of authorization.