When a cannabis edible fails to produce the expected effects, it can be a confusing experience, especially for those familiar with the immediate onset of inhaled cannabis. Edibles are processed by the body in a fundamentally different way than smoking or vaping. The lack of effect can stem from several factors, including individual body chemistry, the mechanics of digestion, your personal history with cannabis, and the quality of the product itself.
The Role of Liver Metabolism
Unlike inhaled cannabis, where Delta-9 THC enters the bloodstream directly through the lungs, ingested THC must first pass through the digestive tract and then travel to the liver. This process, known as the First-Pass Effect, is a significant biological bottleneck that determines the edible experience.
In the liver, enzymes from the Cytochrome P450 family, particularly CYP2C9 and CYP3A4, begin to metabolize the Delta-9 THC. This process converts the compound into a different psychoactive molecule called 11-Hydroxy-THC. The resulting 11-Hydroxy-THC is known to be significantly more potent and crosses the blood-brain barrier more easily than the original Delta-9 THC.
The amount of 11-Hydroxy-THC produced and how quickly it enters the circulation varies greatly from person to person. Genetic variations in the efficiency of these liver enzymes mean some individuals metabolize THC very quickly, producing a strong effect, while others may metabolize it so slowly or inefficiently that the psychoactive compound never reaches an effective concentration in the brain.
Absorption Rate and Waiting Time
The physical mechanics of digestion also play a major role in the delayed or absent effects of an edible. After swallowing, the edible must be broken down in the stomach and intestines before the THC can be absorbed into the bloodstream. This process is inherently slow and can lead to a significant delay in the onset of effects compared to inhalation.
A typical edible can take anywhere from 30 minutes up to two hours to produce effects, with the peak often occurring between two and four hours after consumption. Many people mistakenly assume the edible is not working after an hour and consume a second dose, which can lead to an unpleasantly intense experience when both doses finally kick in.
Consuming an edible on an empty stomach may lead to a faster onset but potentially a less predictable or shorter-lived effect. Ingesting the edible with a meal, especially one containing fats, can slow the onset time by an additional hour or two. Since cannabinoids are fat-soluble, a fatty meal can increase the overall amount of THC absorbed, enhancing bioavailability.
Tolerance Levels and Proper Dosing
Individuals who frequently smoke or vape cannabis develop a systemic tolerance to Delta-9 THC, which often translates to a need for a significantly larger oral dose to achieve comparable effects. The body has adapted to process and respond to the cannabinoid, requiring a higher concentration to stimulate the same physiological response.
The standard recommendation for a starting dose is typically 2.5 milligrams (mg) to 5 mg of THC. Users with a high baseline tolerance from daily inhalation may find that a dose in this range produces no perceptible effect at all.
The best practice for any user is to adopt a “start low and go slow” approach to oral consumption, even with a high inhalation tolerance. This method involves consuming a small, measured dose and patiently waiting the full four-hour window for the effects to peak before considering any increase in the amount. Consistent under-dosing, especially for those with high tolerance, is a frequent reason for the perception that an edible is not working.
Product Quality and Potency Issues
For the THC in cannabis to become psychoactive, it must first undergo a heat-activated chemical process called decarboxylation. This process converts the non-intoxicating precursor, THCA (tetrahydrocannabinolic acid), into the active Delta-9 THC.
If the cannabis used to infuse the edible was not properly or fully decarboxylated, the resulting product will have significantly reduced or non-existent psychoactive effects. Furthermore, the potency of an edible can degrade over time, especially if it is stored incorrectly. Exposure to heat, light, and air can cause the active THC to break down into other, less psychoactive compounds.
Unregulated or homemade products carry a risk of inaccurate potency labeling or uneven distribution of the active compound. Licensed, laboratory-tested products provide greater assurance of the stated milligram dosage. When an edible from a reliable source fails to work, the cause is likely biological; however, if the product is from an untested source, the problem may simply be a lack of active THC.