Nunzio Izzo, 56, of Bella Vista Drive in Glen Cove, was last seen at 11:30 p.m. Dec. 17 leaving a friend's home on Madeline Drive in Glen Cove in a taxi, police said.
Police said Izzo has a pacemaker and a defibrillator and takes medication to prevent seizures but is in good mental health.
Izzo, who is single and lives with his mother, has not taken his anti-seizure medication since he went missing, police said.
Nassau police issued a Silver Alert on Dec. 21 for Izzo, notifying local hospitals of his disappearance.
Anyone with information about his disappearance is asked to call the Glen Cove Police Department at 516-676-1002 or the Nassau County Police Missing Persons Section at 516-573-7347.