http://en.wikipedia.org/wiki/Nutmeg_psychosis
In low doses, nutmeg produces no noticeable physiological or neurological response. Large doses of 7.5 g or more are dangerous, potentially inducing convulsions, palpitations, nausea, eventual dehydration, and generalized body pain. In amounts of 1.0 g or more it is a mild to medium hallucinogen, producing visual distortions and a mild euphoria. Nutmeg Psychosis (see below) and the inconveniently long span for which the effects of a single dose can persist. A user will not experience a peak until approximately six hours after ingestion, and effects can linger for up to three days afterwards. Any unpleasant side-effects would persist throughout this period. [citation needed]
A risk in any large-quantity ingestion of nutmeg is the sudden onset of Nutmeg Psychosis, an acute psychiatric disorder marked by hallucinations, excitement, thought disorder, a sense of impending death and agitation. Some cases have resulted in hospitalization and reportedly few who have experienced the effects of nutmeg poisoning recommend it or repeat the experience. [citation needed]
Even in smaller doses, nutmeg can still be toxic. Ingestion of as little as 3 g may cause dry mouth, fast pulse, fever, flushing and possibly death. It has amphetamine-like effects and may cause the desire to ingest of large volumes of water. It has also been suggested that in small doses, nutmeg can be a trigger for lucid dreaming.
Nutmeg may also be fatal if used regularly in large quantities, but this is not a problem while cooking, since small amounts are used.