THC-COOH (11-Nor-9-carboxy-THC): The Inactive Metabolite | PatientsCann UK

THC-COOH

11-nor-9-carboxy-THC, THC-11-oic acid, carboxy-THC

pronounced: ih-LEV-uhn nor nine kar-BOK-see T-H-C

The inactive metabolite your body makes last, as it packs THC away for removal. It is what most drug tests look for.

Metabolite (body-made)Formula: C21H28O4Intoxicating: No
Type
Metabolite
Formula
C21H28O4
Intoxicating
No
Key focus
Drug tests

11-Nor-9-carboxy-delta-9-THC · 344.4 g/mol

The molecule

Chemical structure

This is the accurate skeletal structure of THC-COOH, drawn from PubChem data. Your body has oxidised the end of the THC molecule all the way to a carboxylic acid (the -COOH group). This switches its activity off. Its formula is C21H28O4 and it weighs 344.4 g/mol.

InactiveDrug-test markerStored in fatLast step

About

What is THC-COOH?

THC-COOH is the main inactive product your body makes as it clears THC. Its full name is 11-nor-9-carboxy-delta-9-tetrahydrocannabinol, which is a mouthful, so almost everyone calls it THC-COOH or carboxy-THC.

It is made in two steps. First your liver turns THC into the strong, active 11-hydroxy-THC. Then it oxidises that into THC-COOH, which no longer causes a high. This is your body switching the medicine off and getting ready to remove it.

In the body

How THC-COOH Works

THC-COOH does not switch on the CB1 receptor, so it produces no high at all. In that sense it does not really "work" in the way THC does. Its job is to be removed.

To do that, your body attaches a sugar (glucuronic acid) to it. This makes it dissolve in water so your kidneys and gut can flush it out. Some laboratory studies have looked at mild anti-inflammatory effects, but it is not used as a medicine.

Receptor snapshot

Where THC-COOH Acts

The endocannabinoid system has two main receptors. Here is how strongly THC-COOH acts on each.

CB1Brain & nervous system
None

Does not switch on CB1. This is why it is inactive and causes no high.

CB2Immune system & body
None

Little to no direct action at CB2 either.

Beyond CB1 and CB2: THC-COOH is the body's inactive "exhaust". It is the compound most urine drug tests are designed to find, because it lingers far longer than THC.

In the body

How THC-COOH is Made

THC-COOH is the final active-to-inactive step. THC becomes 11-hydroxy-THC, which is then oxidised into THC-COOH. A sugar is attached to make it water-soluble, and it is then excreted, mostly in faeces (about 65 to 80 percent) and urine (about 20 to 35 percent).

Because it dissolves into body fat, it is released slowly, which is why it can be found long after the last dose.

Pathway11-OH-THC→THC-COOH→ sugar →excreted

Good to know

Safety and Drug Testing

THC-COOH is not intoxicating and does not impair you. But because it lingers in fat, it can show up on a urine drug test for days after occasional use, and for several weeks in people who use cannabis heavily or who have more body fat.

Being a legal UK patient does not stop the test from being positive. If you drive for work or face workplace testing, tell your prescriber and keep your prescription paperwork to hand.

Questions

THC-COOH: Common Questions

Does THC-COOH get you high?
No. THC-COOH is inactive. It does not switch on the CB1 receptor, so it produces no high. It is simply the form your body makes to pack THC away and remove it.
Why does cannabis stay in your system so long?
THC-COOH dissolves into body fat and is released slowly over time. Most urine drug tests look for THC-COOH, not THC itself, which is why cannabis can be detected for days after occasional use and for several weeks after heavy, regular use.
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Important: This page is for education only. It is not medical advice. Cannabinoid research is still developing, and many studies have been done in cells or animals rather than people. Always speak to your prescriber before changing your treatment. PatientsCann UK does not recommend any specific cannabis product.

References

  1. Huestis, M.A. (2007) 'Human cannabinoid pharmacokinetics', Chemistry & Biodiversity, 4(8), pp. 1770-1804. doi: 10.1002/cbdv.200790152.
  2. Watanabe, K. et al. (2007) 'Cytochrome P450 enzymes involved in the metabolism of tetrahydrocannabinols and cannabinol by human hepatic microsomes', Life Sciences, 80(15), pp. 1415-1419. doi: 10.1016/j.lfs.2006.12.032.
  3. Grotenhermen, F. (2003) 'Pharmacokinetics and pharmacodynamics of cannabinoids', Clinical Pharmacokinetics, 42(4), pp. 327-360. doi: 10.2165/00003088-200342040-00003.
  4. National Center for Biotechnology Information (2025) PubChem Compound Summary for CID 65079, 11-Nor-9-carboxy-Delta9-THC. Bethesda: U.S. National Library of Medicine. Available at: https://pubchem.ncbi.nlm.nih.gov (Accessed: 3 August 2026).