Nutmeg has psychoactive properties at doses much higher than used in cooking. Although these intoxications may be ascribed to the actions of myristicin, it is likely that other components of nutmeg may also be involved, as ingestion of pure myristicin has been found not to produce the same results obtained from ingestion of the entire nutmeg.
Intoxications with nutmeg had effects that varied from person to person, but were often reported to be an excited and confused state with headaches, nausea and dizziness, dry mouth, bloodshot eyes and memory disturbances. Nutmeg was also reported to induce hallucinogenic effects, such as visual distortions and paranoid ideation. Most patients with accidental nutmeg intoxication experience high anxiety and an impending sense of doom after the initial excitation. In the reports, nutmeg intoxication took several hours before maximum effect was reached. Effects and after-effects lasted up to several days.
Recreational use of nutmeg has caused poisoning, requiring medical treatment, characterized by nausea, vomiting, collapse, tachycardia, dizziness, anxiety, headache, hallucinations and irrational behavior. Blood myristicin concentrations may be measured to confirm a diagnosis of poisoning.
Raw nutmeg consists of 5-15% essential oil by mass. 4-8.5% of nutmeg essential oil, or 0.2-1.3% of raw nutmeg, is myristicin. One study found 20 grams of nutmeg to contain 210 mg myristicin, 70 mg elemicin and 39 mg safrole.
While myristicin has been widely accepted as the main psychoactive component of nutmeg (along with elemicin), both the differences in subjective effects observed between nutmeg and synthetic myristicin, as well as the fact that myristicin is not a major component of the seed (therefore is possibly not present in high enough quantities) suggest it does not fully explain the effects of consuming raw nutmeg.
A 1997 study found data to suggest that myristicin can alter the toxicity and / or metabolic pathway of some compounds.
A 1963 study found preliminary evidence that myristicin may be a weak monoamine oxidase inhibitor in mice and rats. The study concluded that more direct evidence will be required.
In a 2005 study it showed possible neurotoxic effects on cultivated human neuroblastoma cells.
This speculation has never been confirmed and studies with the closely related compounds asarone and safrole demonstrated that the proposed transamination reactions did not take place in humans.
However, Alexander Shulgin notes in his book PiHKAL that
"Myristicin and the conjugated isomer isomyristicin are also found in parsley oil, and in dill. This was the oil that was actually shown to be converted to MMDA by the addition of ammonia by passage through an in vitro liver preparation."
^Lee, B. K.; Kim, J. H.; Jung, J. W.; Choi, J. W.; Han, E. S.; Lee, S. H.; Ko, K. H.; Ryu, J. H. (2005). "Myristicin-induced neurotoxicity in human neuroblastoma SK-N-SH cells". Toxicology Letters. 157 (1): 49-56. doi:10.1016/j.toxlet.2005.01.012. PMID15795093.
^Björnstad, K.; Helander, A.; Hultén, P.; Beck, O. (2009). "Bioanalytical Investigation of Asarone in Connection with Acorus calamus Oil Intoxications". Journal of Analytical Toxicology. 33 (9): 604-609. doi:10.1093/jat/33.9.604. PMID20040135.