Fatty acid amide hydrolase (FAAH)

Fatty acid amide hydrolase, or FAAH, is the enzyme that breaks down anandamide and related fatty-acid messengers, ending their signal within minutes.

FAAH is embedded in the membranes inside cells, where it splits anandamide into arachidonic acid and ethanolamine, neither of which activates cannabinoid receptors. Because anandamide is made on demand and not stored, the speed of FAAH largely sets how much anandamide is present at any moment, which is sometimes called endocannabinoid tone. The enzyme also degrades other lipid messengers such as palmitoylethanolamide and oleoylethanolamide, which act at non-cannabinoid targets including PPAR receptors.

A rare inherited FAAH variant that leaves people with high anandamide and unusually low pain sensitivity has drawn wide attention, and drug companies have tested FAAH inhibitors in clinical trials, without success so far. CBD has been reported to inhibit FAAH in some laboratory experiments and to have no effect in others, so its role as an indirect anandamide booster remains a hypothesis rather than an established mechanism.