Smoking cannabis is the most common route of administration. Absorption is more efficient via smoking than ingestion. The effects of smoking marijuana begin almost immediately, usually in 2 to 3 minutes. At lower doses the peak effect is seen at 10 to 20 minutes and the duration of effect is 90 minutes to 2 hours. The oral dose of marijuana must be three to five times greater than the smoked dose to produce equivalent effects.
Tolerance develops to the desired psychoactive effects of marijuana with prolonged use.
Tolerance towards the sedative effects seems to develop before tolerance to the stimulatory effects. The development of tolerance is complex and appears to follow a J-shaped time curve. The initial dip in the curve represents reverse tolerance, whereas the upward sweep represents tolerance. With regular use, marijuana abusers can also develop psychological and mild physical dependence. At doses currently used in the United States, most marijuana users can stop suddenly without fear of severe withdrawal symptoms.