Dr. Peadar O'Grady:

In terms of its adverse effects, it is worth starting with the major benefit of cannabis. Unusually for a medicine, there is no fatal toxic dose. It has never killed anyone. That is true of very few medications, particularly alternative medications for one of the biggest areas of use of cannabis medicinally, which is for pain. Opioids, benzodiazepines and valium-type drugs are commonly used and these are major causes of death. Cannabis does not cause death, which is the first important aspect to understand about it. The second aspect to be understood about it is that it has side effects, which vary depending on the balance of the blend that is being used. Knowing that it does not kill people is important in that while tytrating the dose, which doctors to for pain medications anyway, one starts low, goes slow and builds up slowly. One of the concerns is that if the dose of many drugs is increased too quickly, the patient may be killed. This is not a concern with cannabis. However, all the other side effects such as dry mouth, blurred vision, sedation, somnolence and so on are generally graded low. When authorisation is applied for a drug, regulators are interested in how common are the side effects. Such side effects are common. They are also concerned about their severity but none of these is severe.

The long-term side effects and the particular concern about the development of dependency or psychosis are well described. Doctors are used to dealing with these concerns. Doctors who prescriber opioids and benzodiazepines deal with the dangers of dependency and death but also with the concern about the development of mental health problems in people who use their drugs, and they are well used to advising appropriately when there is a population at risk such as young people and so on. This is the bread and butter of doctors. Trying to make out the risks and benefits, weighing them up and advising their patients accordingly is something unusual and associated only with medicinal cannabis. Any medical practitioner will tell one this is what doctors do for a living every day. There is nothing unusual in cannabis except that it does not kill. That is quite unusual.