The effects of cannabis have varying lengths of time that they have an influence on the body. This presents a dilemma for how long it can affect a person who is using it for medical purposes. A meta-analysis of 80 papers has narrowed down a time frame. It involves such factors as the method of consumption for the cannabis and its strength. The effects can last from between three and ten hours.
The methodology utilized, meta-analysis, is a review and analysis of relevant scientific research. This research then is cross-referenced to arrive at a conclusion based on more methodologies and subjects. In this case, the subjects are people. The information from the findings can in turn assist in giving advice to patients. In addition, it can help users of recreational cannabis make better decisions about driving after consuming cannabis.
THC in particular, can be detected in the body weeks after cannabis consumption, while its stronger effects last for a much shorter period of time. This fact was explained by a psychopharmacologist from the University of Australia in Sydney. The legality would need to be based upon that fact, and not solely on the presence of THC in the blood or saliva.
In the meta-analysis of 80 papers, the research team studied 1,534 performance outcomes from people who had consumed cannanis, and measured how they performed at driving or significant cognitive tasks at various times after they had taken cannabis. The effects depended on how strong the cannabis was, how the cannabis had been taken, such as from inhalation or in the form of edibles, drops or capsules and also on whether the person used cannabis occasionally or regularly. The findings concluded that the effects lasted up to ten hours in higher doses, if consumed orally. When lower doses were consumed, via vaporizing or smoking, and the tasks were simpler, the duration of effects was generally four hours.