Medical research
One study has shown that the compound macelignan isolated from Myristica fragrans (Myristicaceae) may exert antimicrobial activity against Streptococcus mutans, but this is not a currently used treatment.

Toxicity during pregnancy
Nutmeg was once considered an abortifacient, but may be safe for culinary use during pregnancy. However, it inhibits prostaglandin production and contains hallucinogens that may affect the fetus if consumed in large quantities.

History of use
Journalist Jack Shafer has written of nutmeg's long history as a psychoactive substance:
"Can you reach an altered state of consciousness by eating, snorting, or smoking from a tin of nutmeg? You betcha. The medical literature ('Nutmeg Intoxication,' New England Journal of Medicine, July 4, 1963; 'Nutmeg as a Narcotic,' Angewandte Chemie International Edition, June 1971) has long respected the psychoactive powers of this compound. Peter Stafford's Psychedelics Encyclopedia uncovers an 1883 report from Mumbai noting that 'the Hindus of West India take nutmeg as an intoxicant.' Stafford continues, 'Nutmeg has been used for centuries as a snuff in rural eastern Indonesia; in India, the same practice appears, but often the ground seed is first mixed with betel and other kinds of snuff.' In 1829, a Czech physiologist named Jan Evangelista Purkinje washed down three ground nutmegs with a glass of wine and experienced headaches, nausea, euphoria, and hallucinations that lasted several days, which remain a good description of today's average nutmeg binge. One anecdotal report: A drug-savvy friend of mine compares his one nutmeg high to being keelhauled by a freight train on a transcontinental run. He didn't like it, but the substance has its enthusiasts. Harvard ethnobotanist Richard Evans Schultes and chemist Albert Hofmann (father of LSD) wrote of nutmeg's ubiquity in Western culture in their 1980 book The Botany and Chemistry of Hallucinogens. 'Confirmed reports of its use by students, prisoners, sailors, alcoholics, marijuana smokers, and other deprived of their preferred drugs are many and clear. Especially frequent is the taking of nutmeg in prisons, notwithstanding the usual denials by prison officials.' (Malcolm X speaks of getting high on nutmeg 'and the other semi-drugs' while serving time in prison in The Autobiography of Malcolm X.) It has been used as medicine since at least the seventh century and was employed as an abortifacient at the end of the 19th century, which resulted in numerous cases of nutmeg poisoning, according to medical journals. Although used as a folk treatment for other ailments, nutmeg has no proven medicinal value today. According to the Angewandte Chemie International Edition article, nutmeg became popular among young people, bohemians, and prisoners in the post-World War II period, 'and this use was mainly, if not exclusively, confined to the USA.' A 1966 New York Times piece (subscription required) named it along with morning glory seeds, diet aids, cleaning fluids, cough medicine, and other substances as alternative highs on college campuses."

Psychoactivity and toxicity Effects
In low doses, nutmeg produces no noticeable physiological or neurological response, but large doses cause symptoms and harm.
Nutmeg contains myristicin, a weak monoamine oxidase inhibitor. Myristicin poisoning can induce convulsions, palpitations, nausea, eventual dehydration, and generalized body pain. It is also reputed to be a strong deliriant.
Fatal myristicin poisonings in humans are very rare, but two have been reported, in an 8-year-old child and a 55-year-old adult, the latter case attributed to a combination with flunitrazepam.
It should also be noted that the recreational properties of nutmeg can take about four hours to take effect, and large enough doses have been reported to cause severe tiredness, uncontrollable and prolonged sleep coupled with dehydration. The effects have been known to last longer than 72 hours, depending on the size of the dose.
Myristicin poisoning is potentially deadly to some pets and livestock, and may be caused by culinary quantities of nutmeg harmless to humans. For this reason, for example, it is recommended not to feed eggnog to dogs.

The nutmeg tree is any of several species of trees in genus Myristica. The most important commercial species is Myristica fragrans, an evergreen tree indigenous to the Banda Islands in the Moluccas of Indonesia, or Spice Islands. The nutmeg tree is important for two spices derived from the fruit, nutmeg and mace.
Nutmeg is the actual seed of the tree, roughly egg-shaped and about 20 to 30 mm (0.8 to 1 in) long and 15 to 18 mm (0.6 to 0.7 in) wide, and weighing between 5 and 10 g (0.2 and 0.4 oz) dried, while mace is the dried "lacy" reddish covering or aril of the seed. The first harvest of nutmeg trees takes place 7-9 years after planting, and the trees reach full production after 20 years. Nutmeg is usually used in powdered form. This is the only tropical fruit that is the source of two different spices.
Several other commercial products are also produced from the trees, including essential oils, extracted oleoresins, and nutmeg butter (see below).

The outer surface of the nutmeg bruises very easily.
The common or fragrant nutmeg, Myristica fragrans, native to the Banda Islands of Indonesia, is also grown in Penang Island in Malaysia and the Caribbean, especially in Grenada. It also grows in Kerala, a state in southern India. Other species of nutmeg include Papuan nutmeg M. argentea from New Guinea, and Bombay nutmeg M. malabarica from India, called jaiphal in Hindi; both are used as adulterants of M. fragrans products.