Metabolizing Cannabis

Posted on April 23, 2018

In a previous post we discussed how medical cannabis affects us physically and psychologically through the endocannabinoid system. However, the way we consume medical cannabis determines the intensity and duration of those effects. In this post we will discuss the metabolization of medical cannabis, looking at both inhalation and ingestion, and the factors which mediate metabolization for the latter.

Cannabis is ultimately metabolized by the liver, but it reaches there through the blood stream, either through the lungs (inhalation) or small intestine (ingestion).

The following information is on THC in particular. If inhaled, the cannabis is absorbed quickly in the lungs and reaches a high concentration in the blood almost immediately. It is then spread through the body – and to the liver – through blood plasma. Peak THC concentration through inhalation is reached in about 10-15 minutes, rising from the first minute before receding almost completely within a little over an hour.

Ingestion is somewhat more complicated, as the cannabis must travel through more ‘parts’ of the body before reaching the blood stream. Generally, ingestion has a slower and longer onset, being initially absorbed through the small intestine, to the bloodstream, and then to the liver. The onset is about 1-2 hours, reaching peak concentration over the course of 3-6 hours, and recedes after that (taking up to 24 hours for THC levels in the blood to reach 0). Because ingested cannabis must pass through the stomach, if you have eaten it slows gastric emptying and limits the movement of the cannabis to the small intestine where it can be absorbed. The solubility (rate at which it would dissolve) of the THC solution (e.g. an oil) also affects the rate at which it passes through the stomach and the rate at which it is absorbed by the small intestine. Stott et al (2013) found that THC and CBD are absorbed rapidly in a ‘fasted condition’ (wherein the individual had not eaten), reaching peak concentration at 1.5 hours vs. 4 hours for someone who had eaten. However, those who had eaten had greater levels of absorption, 2.8 times higher for THC and 4.1 times higher for CBD after a meal. Another reason to take ingested cannabis with food is that those who ingested in a fasted state were more likely to report anxiety and uneasiness, likely due to the rapid absorption.

The concentration of THC in the bloodstream also differs between inhalation and ingestion (and varies across people, THC concentration of the cannabis consumed, and other factors). For instance, THC concentration can be up to 80mg/ml when inhaled, compared to only about 10mg/ml when ingested. Over time, THC in the blood stream penetrates fat tissues – such as the brain (60% fat) and fat storage throughout the body – thereby reducing the concentration of THC in the blood. This ‘stored THC’ is redistributed back into the blood as overall levels drop, which explains why it THC can linger in the body quite a while after the effects have worn off.

It is necessary to consult with your patient coordinator and physician when deciding how to consume cannabis. As always, the staff at Hello Cannabis are always available to answer any questions you have!


  1. Cooke, J. THC Metabolism. The Sunlight Experiment:
  2. McCormick MC et al. The Health Effects of Cannabis and Cannabinoids: The Current State of Evidence and Recommendations for Research. Washington: The National Academies Press, 2017.
  3. Rupp, M. Human Metabolism of THC. Sapiensoup Blog:
  4. Stott CG, White L, Write S, Wilbraham D, Guy GW. A phase I study to assess the effect of food on the single dose bioavailability of the THC/CBD oromucosal spray. Eur J Clin Pharmacol. 2013 Apr;69(4):825-834.