# THC

> THC (Δ9-tetrahydrocannabinol) is the neutral, decarboxylated cannabinoid mainly responsible for cannabis's reported intoxicating effects; the living plant makes it almost entirely as THCA.

- Canonical: https://genetixbay.com/knowledge/glossary/thc.html
- Also written: delta-9-THC, Δ9-THC, d9, delta 9, tetrahydrocannabinol, delta-9-tetrahydrocannabinol
- Glossary category: Cannabinoids and terpenes · Evidence: Established
- Status: Draft: awaiting expert review · Updated: 2026-10-31
- Licence: CC BY-SA 4.0 (https://creativecommons.org/licenses/by-sa/4.0/), attribute "GenetixBay cannabis glossary"

THC, strictly Δ9-tetrahydrocannabinol, is the neutral [cannabinoid](https://genetixbay.com/knowledge/glossary/cannabinoid.md) that acts on CB1 receptors and is associated with the reported intoxicating effects of cannabis. The plant makes very little of it directly. It makes [THCA](https://genetixbay.com/knowledge/glossary/thca.md), which loses a carboxyl group ([decarboxylation](https://genetixbay.com/knowledge/glossary/decarboxylation.md)) with heat and time to become THC. With further oxidation, THC slowly degrades to [CBN](https://genetixbay.com/knowledge/glossary/cbn.md).

## In practice

On a [COA](https://genetixbay.com/knowledge/glossary/coa.md) for dried flower, Δ9-THC itself is usually a small number, often under 1-2% w/w, while THCA might read 18-25%. The figure on a retail label is normally "total THC", which combines both. When someone says "this plant is 22% THC", they nearly always mean total THC, not the Δ9-THC line.

## Units and formula

Reported as % w/w (or mg/g; 1% = 10 mg/g). [Total THC](https://genetixbay.com/knowledge/glossary/total-thc.md) = Δ9-THC + 0.877 × THCA.

## Don't confuse with

- **THCA**: the acid form the plant actually makes; not intoxicating until decarboxylated.
- **Delta-8 THC**: an isomer present only in traces in the plant; commercial [delta-8](https://genetixbay.com/knowledge/glossary/delta-8-thc.md) is converted from [CBD](https://genetixbay.com/knowledge/glossary/cbd.md).
- **Total THC**: a calculated figure, not a single measured compound.

## Related terms

[THCA](https://genetixbay.com/knowledge/glossary/thca.md), [Decarboxylation](https://genetixbay.com/knowledge/glossary/decarboxylation.md), [Total THC](https://genetixbay.com/knowledge/glossary/total-thc.md), [CBN](https://genetixbay.com/knowledge/glossary/cbn.md), [Delta-8 THC](https://genetixbay.com/knowledge/glossary/delta-8-thc.md)

## Read more

- [Buyer beware: potency labels, strain names and other claims that don't hold up](https://genetixbay.com/knowledge/basics/buyer-beware-label-claims.md)

## Sources

1. ElSohly MA, Slade D. 2005. Chemical constituents of marijuana: the complex mixture of natural cannabinoids. Life Sciences 78(5):539-548.
2. Wang M, Wang YH, Avula B, et al. 2016. Decarboxylation study of acidic cannabinoids: a novel approach using ultra-high-performance supercritical fluid chromatography/photodiode array-mass spectrometry. Cannabis and Cannabinoid Research 1(1):262-271.