It seems that some users have assumed the oral bioavailability is much lower than it actually is, leading many to snort their morphine; this is an amateur's mistake. As a traditional sulfate salt, morphine's intranasal b/a is extremely low (around the 10% range) but at least 3-4x that is absorbed systemically when swallowed. Early trials with MS Contin and other products found bioavailability at 40% orally. Substantially higher than hydromorphone and oxymorphone (The frequent 1 to 3 claim is an under estimate used for the sake of convenience when converting). All this to say; with pharmaceutical morphine; one is wisest either to "suck it up and swallow", or inject into a muscle or vein.
Morphine can be taken orally, rectally, or parenterally. Morphine can be smoked in the form of morphine base. Morphine in its crude form (as a base) can be readily prepared from opium latex, dried poppy seedpods, and bulk quantities of store bought poppy seed as well.
Morphine has an onset of about 60 to 90 minutes after dosing orally, and a rapid onset within minutes after injection (though when injected into a vein it produces effects almost immediately.) Morphine has a half life of 2 to 4 hours which varies with the route administered. Generally with any route, its effects last 3 to 4 hours - while in the case of modified release tablet formulations, effects last 8 to 12 hours.
Though partially absorbed by the bloodstream when taken orally, its bioavailability by this route is typically 40%.
Morphine is an ideal candidate for use in just about any context. It retains at least a portion of its efficacy across the board, meaning by most routes of administration. Some suggest that oral morphine is non euphoric, or "wasteful". As already mentioned, this is not really the case. Swallowing the drug is the next best option for those who don't inject and refuse to shove objects into their wet brown anus hole. The pleasant effects of poppy tea and opium are due mainly to morphine.
The stereotypic model for the effects of opioids (including heroin), is based on the effects of morphine. Such morphine-type effects are - anxiolysis, excitement/euphoria, nausea & vomiting, pruritis/itching, constipation, histamine release, peripheral vasodilation, miosis, myoclonus, smooth muscle rigidity, decrease in biliary secretions, dry mouth or nose, cough suppression, sedation, and respiratory depression.
Morphine is one of the top few alternatives for heroin users when heroin is unavailable. Of all available opioids, the effects of morphine share the greatest degree of similarity with heroin. Some clinical research has shown dependent heroin users may be unable to discriminate the two when given in similar doses; other research has shown that user are able to discriminate the two, but show no preference for one over the other. Though morphine is the next choice to heroin by default, some users prefer hydromorphone or oxymorphone as a second choice, often due to their intense onset and potency. Either way, there remains a great deal of loyalty among users, to the raw heavy high of morphine, with its accompanying warmth & itch (not to mention the overwhelming pins & needles rush during onset).
Morphine's place as the golden standard in narcotics may be due not only to its long history (200+ years) of use, but also due to its flexibility (i.e. its fair strength in several aspects rather than a remarkable strength in limited aspects) - It may be superior in most aspects to morphine derivatives when used orally; bioavailability of 30 to 40%, a relatively marked degree of physiological and subjective effects, and a solid duration of action. Its impressive duration is especially apparent in the case of poppy straw tea.