Wa alaykum salam wa rahmatuLlahi wa barakatuHu,
In Tuhfah 1/289, Ibn Hajar discussed nutmeg along with other substances, like marijuana and opium. He stated that in large amounts it is unlawful. In Hashiyat Sharh al-Rawd 1/9, it is related that consuming these substances in small amounts is not unlawful. Nutmeg can intoxicate in large amounts and it is unlawful because of this quality. Shabramallisi and others stated that if the amount consumed would intoxicate an average person, not including those who have built up a tolerance to the substance, then it is counted as “a lot.”
And Allah knows best.
Answered by: Shaykh Yaqub Abdurrahman