Previous studies have reported conflicting results in terms of acute effects of cannabis in man. Independently of other factors, such discrepancy may be attributable to the different cannabis use history of study volunteers. It is thought that regular cannabis users may develop tolerance to the effects of acute cannabis administration. Here we systematically review all studies examining the effects of single or repeated cannabinoid administration in man as a function of previous cannabis exposure. Research evidence tends to suggest that the acute effects of single cannabinoid administration are less prominent in regular cannabis users compared to non-regular users. Studies of repeated cannabinoid administration more consistently suggest less prominent effects upon repeated exposure. Cognitive function is the domain showing the highest degree of tolerance, with some evidence of complete absence of acute effect (full tolerance). The acute intoxicating, psychotomimetic, and cardiac effects are also blunted upon regular exposure, but to a lesser extent (partial tolerance). Limited research also suggests development of tolerance to other behavioral, physiological, and neural effects of cannabis.

以前的研究报告了关于大麻对人类的急性影响的相互矛盾的结果。独立于其他因素，这种差异可能归因于研究志愿者的不同大麻使用历史。人们认为，经常使用大麻的人可能会对急性大麻给药的影响产生耐受性。在这里，我们系统地回顾了所有研究，这些研究检查了单一或重复使用大麻素对人类的影响，作为先前大麻暴露的函数。研究证据倾向于表明，与非常规使用者相比，单一大麻素给药的急性影响在常规大麻使用者中不太突出。对重复使用大麻素的研究更一致地表明，重复接触后的效果不那么显着。认知功能是表现出最高耐受程度的领域，有一些证据表明完全没有急性效应（完全耐受）。经常接触也会减弱急性中毒、拟精神病和心脏作用，但程度较轻（部分耐受）。有限的研究还表明，人们对大麻的其他行为、生理和神经影响产生了耐受性。