A sprinkle of nutmeg in your coffee is nice, but in the wrong amounts it can cause hallucinations and even death.
Nutmeg contains myristicin, a weak MAOI (monoamine oxidase inhibitor, a class of antidepressant drug). In low doses, like those used in recipes, there is obviously no ill side effect. However, in higher doses it actually is a poison. Taking 2 grams of nutmeg can give the feeling of having taken an amphetamine, and can cause fever, nausea, and headaches. Ingesting 7.5 grams brings on convulsions, palpitations, and extreme pain. At 10 grams the hallucinations set in, along with extreme tiredness, uncontrollable and prolonged sleep, and severe dehydration. Eating an entire nutmeg can lead to a phenomenon called “nutmeg psychosis,” a state of extreme confusion and delirium coupled with a sense of impending doom. And although it is rare, eating large quantities of the spice can cause death. Two cases have been reported—one an 8-year-old boy who ate two whole nutmegs, went into a coma, and died 24 hours later; the other a 55-year-old woman, who had combined a large amount of nutmeg with a muscle relaxant.
Ingesting myristicin is also potentially lethal to animals, even in the doses we use in recipes. So keep the eggnog away from Fido.