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Science of Delta-8-THC vs. Delta-9-THC: Chemistry, Effects, Potency & Production

Published on August 11, 2023 · Last updated August 15, 2023
image of delta-8 consumer and vapor
Delta-8 THC offers a milder experience than Delta-9 THC, and it's often legal in places where Delta-9 isn't. (Illustration: Joshua Titus / Leafly)

Delta-8 vs. Delta-9 THC: Chemistry & Pharmacology

Δ9-THC (“delta-nine”) is the principal psychoactive compound associated with cannabis. By default, when we talk about “THC” we mean delta-9 THC. “Delta-eight” (Δ8-THC) is a nearly identical compound. In the language of chemistry, it’s an isomer of delta-nine-THC–the same number of atoms of each element. As isomers, delta-8 and delta-9 have the same chemical formula, C21H30O2. They differ in the location of a single double bond.

Delta-8 and delta-9 have very similar pharmacology, interacting with very similar receptors in the brain and body. However, the subtle difference in their chemical structure means that they interact with some receptors in slightly different ways. The CB1 receptor, a key part of the endocannabinoid system, is essential for the psychoactive effects of THC. Both delta-9-THC and delta-8-THC activate the CB1 receptor, but delta-9-THC does so more strongly.

Delta-8 vs. Delta-9-THC: Psychoactive Effects

Because delta-8 and delta-9 THC both activate CB1 receptors, both have intoxicating effects (they can get you high). Since delta-8 activates this receptor less strongly than delta-9, its intoxicating effects are expected to be milder. Although delta-8 is “new” in terms of its commercial presence today, it has been known and studied to some extent for several decades, including how the strength of its effects differs from delta-9. For a comprehensive review of delta-8 vs. delta-9 THC, see this review paper.

Animal studies have generally shown that delta-8 causes similar physiological and behavioral effects as delta-9 THC, although a higher dose is typically required. A limited number of historical human studies have seen comparable findings. For example, inhaled delta-8 and delta-9 have produced similar physiological and psychoactive effects (e.g. increases in heart rate, reported ratings of feeling high), with delta-8 being less potent. Roughly speaking, those historical studies indicated that inhaled delta-8 may be roughly half as potent as delta-9.

These scientific results are consistent with what modern-day consumers tend to report for the psychoactive effects of delta-8 THC, often describing it as “lighter” or more “energizing” than a delta-9 THC experience. This is in line with the pharmacological differences between these two versions of THC as well as the dose-dependent, biphasic effects of delta-9: lower doses tend to produce more “euphoric” or “energizing” psychoactive effects, with higher doses of delta-9 more likely to produce relaxation/sedation, a more “stoned” feeling (memory impairment, disorganized thinking), and side effects like anxiety or paranoia.

Delta-8 vs. Delta-9 THC: How Are They Produced?

Cannabis plants do not directly produce cannabinoids like THC. They produce cannabinoid acids, which need to be transformed into cannabinoids. Most commercial plants produce high levels of delta-9 THC-acid (THCA), which must then be decarboxylated (“activated”) into delta-9 THC. This transformation can be achieved by the consumer through heat application (e.g. with a lighter or vaporization device), or the production processes used by manufacturers.

Delta-8 THC is found in negligible levels in Cannabis and therefore not extracted directly from plants. Instead, it is typically synthesized from cannabidiol (CBD) under laboratory conditions. This often involves the extraction of CBD from hemp, which is then chemically transformed into delta-8 THC in the lab through a process called “cyclization.” If you purchase or consume a product high in delta-8 THC, it was likely produced in this way. The way that delta-8 THC is produced has implications for how we might interpret its legal status.

According to the “Farm Bill” (Agriculture Improvement Act of 2018), hemp products containing less than 0.3% delta-9 THC are excluded from the legal definition of marijuana in the Federal Controlled Substances Act. One could argue that delta-8 THC products are not federally illegal if derived from hemp with <0.3% delta-9 THC.

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On the other hand, because delta-8 THC is often produced in the lab through the cyclization of CBD, it can be considered a synthetic cannabinoid. Under this definition, it would be a controlled substance. 

This is a legal question, but one which depends on the scientific details of how delta-8 THC is produced.

US reprimands makers of counterfeit snacks laced with delta-8-THC

Potency, Dose & Biphasic Effects: How to Think About Delta-8 vs. Delta-9 THC

All things considered, it’s reasonable to think of delta-8 as a less potent version of delta-9 THC. Both have intoxicating psychoactive effects, but scientific evidence and anecdotal consumer reports both suggest it’s not as strong as delta-9. With this in mind, it has been interesting to see how people talk about and market delta-8 products. This has sometimes included marketing its effects as qualitatively different from delta-9 THC.

As far as I can tell, there are no obvious, qualitative differences between delta-8 and delta-9 in terms of their psychoactive effects. Instead, differences can be explained by potency and dose. It’s well-established that delta-9, like many drugs, has dose-dependent effects. At a relatively low dose it will likely have effects different from those seen at a higher dose. Think about it in common sense terms: if you take a couple puffs of a joint, you’re going to feel very different than if you smoke several grams of the same weed by yourself. The lower dose is obviously going to have “lighter” effects. Your high will probably be better described with words like “euphoric” or “energizing,” while the larger dose will make you feel more “stoned.” This is the biphasic effect.

If delta-8 can be thought of as a lower potency version of delta-9, then you’re going to have to consume a higher dose to feel the effects you would get from delta-9. If you prefer the effects you tend to get from delta-8 products, this would simply mean you prefer the effects of a lower dose delta-9 experience compared to a high dose experience. If that describes you, then it’s worth considering your delta-9 THC shopping habits. If you enjoy that “lighter,” less “stoney” feeling, then you would want to consume either a smaller quantity of a high-delta-9 THC product, or else stop worrying about buying products with the highest THC percentage possible. This is especially true if you enjoy the ritual of, say, rolling and smoking an entire joint. If the “delta-8 high” is what you’re after, then consuming a delta-9 product may get you to the same place, as long as it’s a lower potency product.

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Nick Jikomes, PhD
Nick Jikomes, PhD
Nick is Leafly's Director of Science & Innovation and holds a PhD in Neuroscience from Harvard University and a B.S. in Genetics from the University of Wisconsin-Madison. He is the host of a popular science podcast, Mind & Matter: https://mindandmatter.substack.com. You can follow him on Twitter: @trikomes
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