Stoners have believed since time immemorial that holding smoke in your lungs for longer while smoking a joint makes you more stoned. Studies of this, however, found it not to be the case.
The name of the game
If you want to get more stoned from delta-9-tetrahydrocannabinol (THC, the ingredient of cannabis that makes you high), the name of the game is bioavailabiity: how much your body absorbs. An article by the US National Library of Medicine in 2007 reported that the average bioavailability of THC was 30% when it was smoked compared to a mere 4 to 12% when taken orally. A study by the American Society for Clinical Pharmacology and Therapeutics that took place in 1980 examined 11 healthy people who received THC intravenously, orally and by smoking. Taking it intravenously was as good as smoking if you fancy injecting (which you probably don’t) but, again, taking it orally had much less effect.
Does holding it in do any good?
A study by the National Library of Medicine in 1989 looked at eight regular consumers of cannabis and how long they held the smoke in – 0, 10 or 20 seconds – on three occasions. The number of puffs and puff volume were kept the same. Monitoring of such things as heightened heart rate, how stoned the person felt and reduced memory performance took place. The upshot was that there was “little evidence” of holding it in making you more stoned. A second study by the same outfit in 1991 again found that breath-hold duration didn’t make you more stoned. This looked at 10 pot smokers over eight smoking sessions. Once more, number of puffs and puff volume were kept constant.
It seems that how stoned you get doesn’t depend on how long you hold the smoke in. Rather, it is the quantity of smoke you inhale. That depends on user ability and how deeply the person inhales.
Stick it up your arse
There are other ways to take cannabis. Another is transcutaneously, ie through the skin, which delivers THC to the brain more slowly. Experiments with monkeys evaluated the effect of taking THC rectally. The bioavailability was, at most, 13.5%. This was more than for the oral route but, very thankfully, less than for smoking.
EDIT: Looks like this one might not be right.