AUGUSTA — A new state law allowing veterans and others suffering from post-traumatic stress disorder to be prescribed medical marijuana will help them live a normal life, advocates and veterans say.

Under the law that went into effect Wednesday, PTSD joins cancer, glaucoma, hepatitis C and others on the list of conditions patients must have to qualify for medical marijuana use in Maine.

Hundreds of Maine veterans already use marijuana to treat PTSD, but they weren’t previously able to get it from their doctors, said Paul McCarrier, legislative liaison for the Medical Marijuana Caregivers of Maine.

“This unties the hands of doctors to allow them to treat their patients,” he said.

Retired Marine Corps Sgt. Ryan Begin is one of those veterans already using the drug. Begin lost 4 inches of his right arm, including his elbow, from an IED explosion during his second tour in Iraq in 2004. He started using medical marijuana to deal with the pain, but it has also helped manage his PTSD, which caused flashbacks and nightmares, he said.

“It balances me,” the 33-year-old Belfast resident said. “Instead of being on a roller coaster … you’re more even keeled. … You don’t get too far up, and you don’t get too far down.”

Maine voters legalized marijuana for medical purposes in 1999 and approved a law creating a statewide network of marijuana dispensaries 10 years later. Twenty states and the District of Columbia have legalized medical marijuana use, but only six other states allow its use for PTSD, according to the Marijuana Policy Project, a D.C.-based advocacy group.

Gordon Smith, executive vice president of the Maine Medical Association, said the question of medical marijuana use for PTSD treatment is contentious among the medical community.

“We heard both from doctors who felt that particularly people coming back from Afghanistan might be assisted (by it), and we heard from doctors who thought there was not a sound evidentiary basis for it,” Smith said.

Because the drug is still illegal under federal law, there is a lack of federally funded studies on medical marijuana. That has been a challenge to understanding its impact on various conditions, Smith said.

The U.S. Department of Veterans Affairs changed its policy on medical marijuana in 2011 to ensure veterans using medical marijuana in states where it’s legal aren’t punished, said Michael Krawitz, director of the Virginia-based group Veterans for Cannabis Access. But VA doctors still can’t recommend medical marijuana for treatment or provide documentation to get it.

McCarrier said he suspects the new law will bring many new patients into Maine’s medical marijuana program, which had more than 1,450 patients registered with the state in 2012.

Efforts to expand the program to include more qualifying conditions will likely continue in Maine. The first draft of the proposed law would have allowed doctors to prescribe marijuana for any condition they deemed necessary. But the Maine Medical Association opposed that, saying that expanding the program to virtually every condition could essentially legalize recreational marijuana use.

Begin said the new law will be a huge step forward for veterans struggling with PTSD. That’s because marijuana doesn’t cause the negative side effects that prescription medication can, like feelings of weakness or depression, but instead allows patients to stay medicated while remaining social and productive, he said.

“Just because they have to take medication, they shouldn’t be put on the sidelines of life,” he said.