No national standard exists to determine how long someone should wait to drive after consuming marijuana. However, experts at the Colorado Department of Public Health and Environment recommend waiting at least six hours after smoking less than 35 milligrams of THC and eight hours after eating or drinking something containing less than 18 milligrams.
For reference, a “typical” marijuana cigarette contains at least 60 milligrams of THC, and most edibles contain around 10 milligrams per serving size. A 12-hour wait is safer, as the high (and subsequent drowsiness) from smoking a typical amount lasts far longer.
