The European Monitoring Centre for Drugs and Drug Addiction (EMCDDA) was established in 1993. It is one of the EU’s decentralised agencies.

The EMCDDA exists to facilitate a more evidence-informed understanding of issues that are important for developing better drug-related policies and actions across Europe. In a new series of reports, it turns its attention to cannabis, a substance with a long history of use that has recently emerged as a controversial and challenging issue in both European and wider international drug policy debates.

Cannabis is the most commonly used illicit drug in Europe. It is also the drug about which both public attitudes and the political debate are most polarized. Interest in this area is rapidly growing, prompted by some quite dramatic international developments in the ways in which some countries and jurisdictions are now regulating this substance.

In this report, EMCDDA examined the evidence for, and practice of, making cannabis or cannabis-based medicines available for therapeutic purposes. The new 48 page EMCDDA report concluded that the evidence is still thin on the medical use of cannabis. The Lisbon-based EMCDDA said in its first report on the topic that so far there were “important gaps in the evidence“.

One of the most commonly reported reasons patients use cannabis for medical purposes in the United States is to treat chronic pain that is not caused by cancer (chronic non-cancer pain, CNCP). This includes neuropathic pain, arthritis, back pain, neck and shoulder pain, and headaches.

A review of studies on the effects of cannibis on CNCP showed a “Small (but statistically significant) effect compared with placebo.” Other areas of medical use were also reviewed. For example, other medical uses, such as sleep disorders, anxiety disorders, depression, degenerative neurological disorders, and inflammatory bowel disease the evidence was rated as “insufficient.”

The short-term adverse effects of medical cannabinoids and cannabis have been evaluated in the clinical trials reported in this study. In general, the short-term adverse events reported were similar to those of other commonly used medicines and related to symptoms such as dizziness, dry mouth, disorientation, nausea, euphoria, confusion and somnolence. Serious adverse events were rare.

There is less evidence about the risks of long-term medical use of cannabinoids, but in general those reported are similar to those reported for short-term use. Over time, more people report adverse events, but these are generally mild to moderate.

A handful of regulated pharmaceuticals use chemicals derived from cannabis, such as GW Pharmaceuticals’ Sativex which is approved for treating symptoms of multiple sclerosis. But cannabis itself and most products made from it are governed by countries’ individual criminal laws on illegal drugs, which may or may not allow medicinal use.