CHICAGO (AP) — Randy Gross hopes a new law allowing children into Illinois’ medical marijuana program will reunite his family, nearly a year after his wife moved to Colorado so their son could receive a controversial treatment to ease his epileptic seizures.

Gross lives and works in Illinois. His wife, Nicole, moved with their two sons so their 8-year-old could legally swallow a quarter-teaspoon of marijuana oil each day. While the medical evidence is thin, some parents — including the Grosses — say marijuana works for their children and they’re willing to experiment.

“We can tell he’s feeling better,” Nicole Gross said of their son, Chase, who also has autism and uses sign language. “He puts four or five signs together. He’ll sign, ‘brother go downstairs play.’ ... He engages more, makes better eye contact. If he notices something funny on his TV show, he’ll clap and pat you on the back.”

The boy formerly suffered abrupt “head drop” seizures — at least one every two minutes, she said. Now 20 minutes go by, sometimes 30 minutes, between seizures, she said.

The dark green, pungent oil comes from a hybrid marijuana strain called Charlotte’s Web, which was cultivated by a Colorado company to be heavy in a compound called CBD and low in THC, the ingredient that gets people high. It hasn’t been tested in clinical trials for effectiveness or safety, but it will be legal in Illinois under a law that took effect Thursday.

Sorting truth from hype is difficult. CBD shows enough promise that two drug companies are studying it for childhood seizures with support from U.S. regulators, but those results will take years. For now, mainstream medicine regards Charlotte’s Web as a folk remedy deserving of caution.

“There is good evidence of long-term harm of chronic marijuana use on the developing brain under 18 years of age,” said Dr. Leslie Mendoza Temple, a suburban Chicago doctor who has given accredited lectures about medical marijuana for the Illinois Academy of Family Physicians.

She considers the scientific evidence sparse, so “in general, this is a medicine only to be considered when all other therapies have been exhausted and failed, and if the child is quite debilitated.”

A wave of Charlotte’s Web publicity, sparked by a 2013 CNN documentary, lured families to Colorado and unfairly played on their desperation, said Dr. Kevin Chapman, who treats children with epilepsy at Children’s Hospital Colorado. Chapman has seen only inconsistent parent accounts that Charlotte’s Web works.

When he and his colleagues reviewed the charts of 58 young patients using the oil, they found less than a third of parents reported a big reduction in seizures, and the improvement didn’t show up on available before-and-after tests that measure brain waves. Families who moved to Colorado to use the drug, however, were three times more likely to report improvement than families already living in the state.

“Families have to move, sell everything, pack up, leave their social network,” Chapman said. “It’s hard to be truly objective if you’ve had to do so much to get this drug that’s been touted as a miracle medication.”

Under emergency rules, the Illinois Department of Public Health announced in December, young patients will be able to use medical marijuana for any of the nearly 40 health conditions already authorized for adults, although some — like agitation of Alzheimer’s disease — aren’t childhood conditions.

Children will be required to get written certification from two doctors. Adult patients need just one doctor to sign off.

Illinois doctors will be reluctant to sign children’s forms, and for good reason, said Dr. Joel E. Frader, a Northwestern University bioethicist and palliative care pediatrician at Lurie Children’s Hospital in Chicago. Signing means a doctor believes there will be a therapeutic benefit that outweighs the risks.

“I know there are a lot of parents who feel desperate, and my heart certainly goes out to them,” Frader said. “In Illinois, there has been pressure put on the state Legislature and the regulatory process to increase the scope of use for medical marijuana by families who look at this as their last hope.”

No legal marijuana has yet been grown in Illinois yet. Potential growers waiting to learn whether they’ve been granted permits must build secure facilities before they can plant the first crop. That means it may be summer before marijuana oil is available in Illinois.

Randy Gross, who works as a chief information officer for a trade group, hopes to bring his wife and sons back home. He tries to spend two weeks each month with them in Colorado. It’s been difficult for the family, particularly his 10-year-old son, Zach.

“I missed his first karate tournament. I missed my wife’s birthday and Valentine’s Day,” he said. “It’s the little things like that.”