Catalyzes the hydrolysis of endogenous amidated lipids like the sleep-inducing lipid oleamide ((9Z)-octadecenamide), the endocannabinoid anandamide (N-(5Z,8Z,11Z,14Z-eicosatetraenoyl)-ethanolamine), as well as other fatty amides, to their corresponding fatty acids, thereby regulating the signaling functions of these molecules (PubMed:9122178, PubMed:17015445, PubMed:19926788). Hydrolyzes polyunsaturated substrate anandamide preferentially as compared to monounsaturated substrates (PubMed:9122178, PubMed:17015445). It can also catalyze the hydrolysis of the endocannabinoid 2-arachidonoylglycerol (2-(5Z,8Z,11Z,14Z-eicosatetraenoyl)-glycerol) (PubMed:21049984). FAAH cooperates with PM20D1 in the hydrolysis of amino acid-conjugated fatty acids such as N-fatty acyl glycine and N-fatty acyl-L-serine, thereby acting as a physiological regulator of specific subsets of intracellular, but not of extracellular, N-fatty acyl amino acids (By similarity). H2O + N-(5Z,8Z,11Z,14Z-eicosatetraenoyl)-ethanolamine = (5Z,8Z,11Z,14Z)-eicosatetraenoate + ethanolamine (9Z)-octadecenamide + H2O = (9Z)-octadecenoate + NH4(+) 2-(5Z,8Z,11Z,14Z-eicosatetraenoyl)-glycerol + H2O = (5Z,8Z,11Z,14Z)-eicosatetraenoate + glycerol + H(+) H2O + N-(9Z-octadecenoyl) ethanolamine = (9Z)-octadecenoate + ethanolamine H2O + N-hexadecanoylethanolamine = ethanolamine + hexadecanoate H2O + hexadecanamide = hexadecanoate + NH4(+) H2O + tetradecamide = NH4(+) + tetradecanoate H2O + N-(9Z-octadecenoyl)-taurine = (9Z)-octadecenoate + taurine (9Z,12Z,15Z)-octadecatrienamide + H2O = (9Z,12Z,15Z)-octadecatrienoate + NH4(+) (5Z,8Z,11Z,14Z)-eicosatetraenamide + H2O = (5Z,8Z,11Z,14Z)-eicosatetraenoate + NH4(+) (6Z)-octadecenamide + H2O = (6Z)-octadecenoate + NH4(+) (15Z)-tetracosenamide + H2O = (15Z)-tetracosenoate + NH4(+) (8Z,11Z,14Z)-eicosatrienamide + H2O = (8Z,11Z,14Z)-eicosatrienoate + NH4(+) (11Z,14Z,17Z)-eicosatrienamide + H2O = (11Z,14Z,17Z)-eicosatrienoate + NH4(+) (11Z,14Z)-eicosadienamide + H2O = (11Z,14Z)-eicosadienoate + NH4(+) (9Z,12Z)-octadecadienamide + H2O = (9Z,12Z)-octadecadienoate + NH4(+) 1-O-methyl-(5Z,8Z,11Z,14Z)-eicosatetraenoate + H2O = (5Z,8Z,11Z,14Z)-eicosatetraenoate + H(+) + methanol (11Z)-eicosenamide + H2O = (11Z)-eicosenoate + NH4(+) H2O + N-(9Z-hexadecenoyl) ethanolamine = (9Z)-hexadecenoate + ethanolamine H2O + N-octadecanoyl ethanolamine = ethanolamine + octadecanoate H2O + N-docosanoyl-ethanolamine = docosanoate + ethanolamine H2O + N-tetracosanoyl-taurine = taurine + tetracosanoate H2O + N-(15Z-tetracosenoyl)-ethanolamine = (15Z)-tetracosenoate + ethanolamine H2O + N-docosanoyl-taurine = docosanoate + taurine H2O + N-(15Z-tetracosenoyl)-taurine = (15Z)-tetracosenoate + taurine H2O + N-tricosanoyl-taurine = taurine + tricosanoate (9Z)-octadecenoate + glycine = H2O + N-(9Z-octadecenoyl)glycine H2O + N-(5Z,8Z,11Z,14Z)-eicosatetraenoyl-glycine = (5Z,8Z,11Z,14Z)-eicosatetraenoate + glycine H2O + N-(5Z,8Z,11Z,14Z-eicosatetraenoyl)-L-serine = (5Z,8Z,11Z,14Z)-eicosatetraenoate + L-serine Inhibited by O-aryl carbamates and alpha-keto heterocycles (PubMed:17015445). Inhibited by trifluoromethyl ketone (PubMed:9122178). Optimum pH is around 9.0. Homodimer. Seems to be attached to intracellular membranes and a portion of the cytoskeletal network. Highly expressed in the brain, small intestine, pancreas, skeletal muscle and testis. Also expressed in the kidney, liver, lung, placenta and prostate. Genetic variations in FAAH can be associated with susceptibility to polysubstance abuse [MIM:606581]. At homozygosity, variant Thr-129 is strongly associated with drug and alcohol abuse, and methamphetamine dependence. Belongs to the amidase family.