Dave Warden displays the wares at a Los Angeles marijuana dispensary.

IS MARIJUANA A MEDICINE?

Charlene DeGidio never smoked marijuana in the 1960s, or afterward. But a year ago, after medications failed to relieve the pain in her legs and feet, a doctor suggested that the Adna, Wash., retiree try the drug.

Ms. DeGidio, 69 years old, bought candy with marijuana mixed in. It worked in easing her neuropathic pain, for which doctors haven't been able to pinpoint a cause, she says. Now, Ms. DeGidio, who had previously tried without success other drugs including Neurontin and lidocaine patches, nibbles marijuana-laced peppermint bars before sleep, and keeps a bag in her refrigerator that she's warned her grandchildren to avoid.

"It's not like you're out smoking pot for enjoyment or to get high," says the former social worker, who won't take the drug during the day because she doesn't want to feel disoriented. "It's a medicine."

For many patients like Ms. DeGidio, it's getting easier to access marijuana for medical use. The U.S. Department of Justice has said it will not generally prosecute ill people under doctors' care whose use of the drug complies with state rules. New Jersey will become the 14th state to allow therapeutic use of marijuana, and the number is likely to grow. Illinois and New York, among others, are considering new laws.

As the legal landscape for patients clears somewhat, the medical one remains confusing, largely because of limited scientific studies. A recent American Medical Association review found fewer than 20 randomized, controlled clinical trials of smoked marijuana for all possible uses. These involved around 300 people in all--well short of the evidence typically required for a pharmaceutical to be marketed in the U.S.

Doctors say the studies that have been done suggest marijuana can benefit patients in the areas of managing neuropathic pain, which is caused by certain types of nerve injury, and in bolstering appetite and treating nausea, for instance in cancer patients undergoing chemotherapy. "The evidence is mounting" for those uses, says Igor Grant, director of the Center for Medicinal Cannabis Research at the University of California, San Diego.

But in a range of other conditions for which marijuana has been considered, such as epilepsy and immune diseases like lupus, there's scant and inconclusive research to show the drug's effectiveness. Marijuana also has been tied to side effects including a racing heart and short-term memory loss and, in at least a few cases, anxiety and psychotic experiences such as hallucinations. The Food and Drug Administration doesn't regulate marijuana, so the quality and potency of the product available in medical-marijuana dispensaries can vary.

Though states have been legalizing medical use of marijuana since 1996, when California passed a ballot initiative, the idea remains controversial. Opponents say such laws can open a door to wider cultivation and use of the drug by people without serious medical conditions. That concern is heightened, they say, when broadly written statutes, such as California's, allow wide leeway for doctors to decide when to write marijuana recommendations.

But advocates of medical-marijuana laws say certain seriously ill patients can benefit from the drug and should be able to access it with a doctor's permission. They argue that some patients may get better results from marijuana than from available prescription drugs.

Glenn Osaki, 51, a technology consultant from Pleasanton, Calif., says he smokes marijuana to counter nausea and pain. Diagnosed in 2005 with advanced colon cancer, he has had his entire colon removed, creating digestive problems, and suffers neuropathic pain in his hands and feet from a chemotherapy drug. He says smoking marijuana was more effective and faster than prescription drugs he tried, including one that is a synthetic version of marijuana's most active ingredient, known as THC.

The relatively limited research supporting medical marijuana poses practical challenges for doctors and patients who want to consider it as a therapeutic option. It's often unclear when, or whether, it might work better than traditional drugs for particular people. Unlike prescription drugs it comes with no established dosing regimen.

"I don't know what to recommend to patients about what to use, how much to use, where to get it," says Scott Fishman, chief of pain medicine at the University of California, Davis medical school, who says he rarely writes marijuana recommendations, typically only at a patient's request.

Researchers say it's difficult to get funding and federal approval for marijuana research. In November, the AMA urged the federal government to review marijuana's position in the most-restricted category of drugs, so it could be studied more easily.

Gregory T. Carter, a University of Washington professor of rehabilitation medicine, says he's developed his own procedures for recommending marijuana, which he does for some patients with serious neuromuscular conditions such as amyotrophic lateral sclerosis, or Lou Gehrig's disease, to treat pain and other symptoms. He typically urges those who haven't tried it before to start with a few puffs using a vaporizer, which heats the marijuana to release its active chemicals, then wait 10 minutes. He warns them to have family nearby and to avoid driving, and he checks back with them after a few days. Many are "surprised at how mild" the drug's psychotropic effects are, he says.

States' rules on growing and dispensing medical marijuana vary. Some states license specialized dispensaries. These can range from small storefronts to bigger operations that feel more like pharmacies. Typically, they have security procedures to limit walk-in visitors.

At least a few dispensaries say they inspect their suppliers and use labs to check the potency of their product, though states don't generally require such measures. "It's difficult to understand how we can call it medicine if we don't know what's in it," says Stephen DeAngelo, executive director of the Harborside Health Center, a medical-marijuana dispensary in Oakland, Calif.

Some of the strongest research results support the idea of using marijuana to relieve neuropathic pain. For example, a trial of 50 AIDS patients published in the journal Neurology in 2007 found that 52% of those who smoked marijuana reported a 30% or greater reduction in pain. Just 24% of those who got placebo cigarettes reported the same lessening of pain.

Marijuana has also been shown to affect nausea and appetite. The AMA review said three controlled studies with 43 total participants showed a "modest" anti-nausea effect of smoked marijuana in cancer patients undergoing chemotherapy. Studies of HIV-positive patients have suggested that smoked marijuana can improve appetite and trigger weight gain.

Donald Abrams, a doctor and professor at the University of California, San Francisco who has studied marijuana, says he recommends it to some cancer patients, including those who haven't found standard anti-nausea drugs effective and some with loss of appetite.

Side effects can be a problem for some people. Thea Sagen, 62, an advanced neuroendocrine cancer patient in Seaside, Calif., says she expected something like a pharmacy when she went to a marijuana dispensary mentioned by her oncologist. She says she was disappointed to find that the staffers couldn't say which of the products, with names like Pot 'o Gold and Blockbuster, might boost her flagging appetite or soothe her anxiety. "They said, 'it's trial and error,' "she says. "I was in there flying blind, looking at all this stuff."

Ms. Sagen says she bought several items and tried one-eighth teaspoon of marijuana-infused honey. After a few hours, she was hallucinating , too dizzy and confused to dress herself for a doctor's appointment. Then came vomiting far worse than her stomach upset before she took the drug. When she reported the side effects to her oncologist's nurse and her primary-care physician, she got no guidance. She doesn't take the drug now. But with advice from a nutritionist, her appetite and food intake have improved, she says.

Other marijuana users may experience the well-known reduction in ability to concentrate. At least a few users suffer troubling short-term psychiatric side effects, which can include anxiety and panic. More controversially, an analysis published in the journal Lancet in 2007 tied marijuana use to a higher rate of psychotic conditions such as schizophrenia. But the analysis noted that such a link doesn't necessarily show marijuana is a cause of the conditions.

Long-term marijuana use can lead to physical dependence, though it is not as addictive as nicotine or alcohol, says Margaret Haney, a professor at Columbia University's medical school. Smoked marijuana may also risk lung irritation, but a large 2006 study, published in Cancer Epidemiology, Biomarkers & Prevention, found no tie to lung cancer.