Initial results on studies evaluating the effectiveness of the marijuana extract cannabidiol (CBD) for treating severe epilepsy in children are mixed, according to The Wall Street Journal.

Some parents consider CBD to be a wonder drug for treating their children’s severe epilepsy, the article notes. A dozen states have legalized CBD in the past year, and an additional nine states are considering legislation to make the substance legal. Most of the laws and bills allow CBD only to treat severe forms of epilepsy. CBD does not generate a high. It is available in an oil form that can be taken orally. Some families of children with seizures, who call themselves “marijuana refugees,” have moved to Colorado to gain access to CBD. Studies have found some children with seizures appear to improve after taking CBD, but others do not respond, or even get worse. The substance is also being studied as a potential treatment for schizophrenia, anxiety and other conditions.

“We don’t have enough data at this point to recommend marijuana products for families,” said Kevin Chapman, a neurologist at Children’s Hospital Colorado, who co-authored a study released at an American Epilepsy Society meeting in December. His study included 75 children who took CBD, and found in 33 percent, seizures decreased by more than half. Chapman found 44 percent of children experienced adverse effects after taking CBD, including increased seizures.