Understanding Cannabis Bioavailability

Only a small portion of THC is absorbed by the body after consuming cannabis edibles. Meanwhile, CBD is ten times more effectively absorbed through the skin. Why does this happen? Find out in this article.

Bioavailability refers to the amount and rate at which a substance is absorbed into the human body. Simply put, the higher the bioavailability, the less of the substance is lost during absorption and use by the body. Physiological processes and methods of consumption can affect how cannabis is absorbed, resulting in different effects.

What Factors Affect Cannabis Bioavailability?

THC and CBD oils resist absorption into the bloodstream because the human body is about 60% water.

“Cannabinoids are fat-loving molecules. But when they enter the human body, they have to pass through a cellular environment that is watery or aqueous,” explains Dr. Patricia Frye, a member of the Society of Cannabis Clinicians and Chief Medical Officer at Hello MD.

When cannabis is consumed as an oil, the onset of effects can be delayed and bioavailability is limited. Another phenomenon that restricts the entry of oil-based cannabis extracts into the bloodstream is the first-pass effect. When cannabis is ingested, it is absorbed in the gastrointestinal tract and transported through the portal vein to the liver, where it is metabolized. As a result, only a limited amount reaches the circulatory system. That’s why cannabis oils have a milder effect due to absorption challenges.

Are Some Cannabinoids More Bioavailable Than Others?

Some research has been conducted on CBD, THC, and CBN. Studies show that the bioavailability of cannabinoids depends on the method of cannabis consumption.

• When applied as a topical, CBD and CBN can penetrate the skin ten times more effectively than THC.
• However, THC is more bioavailable than CBD when taken orally (by mouth) or delivered through the lungs.
• A clinical study found that blood concentrations of THC were 30-50% higher than CBD after oral use as a sublingual spray.

Still, the bioavailability of THC remains limited with oral consumption, averaging only 4-12%. When smoked or vaporized, THC bioavailability increases to about 30% on average.

Which Consumption Methods Optimize Bioavailability?

Some of the most common and convenient cannabis products, such as tinctures and edibles, limit bioavailability due to the first-pass effect in the liver. However, oral consumption lasts longer than smoking, reducing the need for frequent dosing. Edible methods also avoid irritation of the respiratory tract.

Inhalation of cannabis ensures higher bioavailability, as vapor particles carry the molecules directly into the alveoli in the lungs. This allows cannabinoids to quickly enter the bloodstream without being metabolized by the liver.

Another lesser-known method is intranasal delivery (through the nose), which allows cannabinoids to be easily absorbed with rapid onset—within ten minutes or less.

“Intranasal methods are highly bioavailable at 34-46%,” says Frye. “This is especially useful for patients with seizures or those who want to stop an oncoming seizure or migraine.”

Topical creams can be very effective for localized or systemic pain. They deliver active cannabinoids to a specific area without exposing the bloodstream to THC and its psychoactive effects.

Tips and Tricks to Increase Bioavailability

• One way to increase absorption of edibles is to combine cannabis products with fats. For example, eat something fatty along with your edible.
• For those who smoke or vape, simply increasing the number of puffs can help. However, there is no evidence that holding your breath increases the effect, so it’s not recommended.