Medical marijuana may alleviate certain symptoms in patients with multiple sclerosis, according to new guidelines issued by the American Academy of Neurology.

Though complementary and alternative medicine (CAM) therapies - such as medical marijuana- are popular among those with multiple sclerosis, few guidelines exist to "help patients to determine the effectiveness of these therapies, Dr. Pushpa Narayanaswami told Fox News.

"We wanted to review the literature well and see where we went with it, to guide patients and physicians as well," Narayanaswami, an assistant professor of neurology at Harvard Medical School, said. "There's nothing out there that looks at all of these to see how effective and safe they are."

For the study, researchers examined and compared data on all known alternative therapies, including medical marijuana pills and oral medical marijuana spray. After reviewing 2,608 studies researchers were able to assess which forms of CAM therapies had sufficient evidence to indicate that they may be effective for patients with multiple sclerosis.

They found that certain forms of medical marijuana - a spray form and a pill form - appeared to have the most evidence indicating they may be helpful in patients with multiple sclerosis.

"What we learned are these specific forms of medical marijuana can ease patients' symptoms - specific symptoms of spasticity, or muscle stiffness ... and helped with frequent urination," Narayanaswami said.

According to the Examiner, researchers are not sure id marijuana accomplishes symptom relief on its own or enhances the effects of commonly used multiple sclerosis drugs.

Other effects of multiple sclerosis, including tremors or urinary incontinence, were not relieved by medical marijuana. The alternative drug also carried some negative effects, including drowsiness, dizziness, and cognitive problems in some people, Fox News reported.

Researchers also said the use of marijuana in some people may promote depression. Since depression is a common symptom in patients with multiple sclerosis, the combination of the two could result in a higher potential for suicide, the Examiner reported.