Medical cannabis has been getting a lot of good press in recent years. Reports and patients’ testimonies of how they benefitted from ingesting the plant or its extract have spread rapidly and the Health Ministry’s medical cannabis unit issues some 50 new permits for using it weekly.

But while the demand for cannabis is soaring, many questions remain open regarding its effects. An Israeli study now aims for the first time to find out whether patients experience any after-effects, how many of them stop using it and why.

It has been previously estimated that by 2018 the Health Ministry will issue some 40,000 permits, compared to some 25,000 today (patients who are prescribed with medical cannabis are required to obtain a ministry permit). At the same time the number of doctors authorized to prescribe cannabis is expected to rise from 20 to 30.

“There’s a lot of enthusiasm, especially in the media, about medical cannabis,” says Prof. Pessah Schwartzman, chair of the Health Ministry Commission for the Organization of National Palliative Care Services, who heads the study.

“Many people find no solution in conventional medicine and turn elsewhere for relief," says Schwartzman, "but medical cannabis entered Israel by the back door and there’s a lot we don’t know about it. In Israel and the world there’s anecdotal evidence about the use of cannabis, showing that it can be beneficial in certain conditions. The most common condition is usually pain from a neurological source. There’s also evidence it helps in cases of multiple sclerosis. Some cancer patients testify that it helps in cases of appetite loss and nausea. In contrast, there are negative effects such as severe cases of psychosis.”

The study, launched some six months ago, is financed by the National Institute for Health Policy Research. It is conducted together with Dr. Silvio Brill, who heads the pain treatment unit at Tel Aviv's Ichilov Hospital and is also chairman of the Israel Pain Association, and Dr. Itay Gur-Arie, the head of the Sheba Medical Center, Tel Hashomer's pain management unit.

The study, which will follow new cannabis users for two years, will be based on interviews held with 1,500-2,000 patients who agreed to take part in the project. The interviews will be held every three months, enabling the scientists to ascertain the cannabis’ effect and effectiveness, as well as which uses are more effective and what kind of patients benefit the most from it.

“We couldn’t find any similar study in the world,” Schwartzman said. “It’s a rapidly growing business and we need to know what we’re doing to our patients when we give them cannabis.”