Nadler was at an event at PS 149 in Manhattan touting an increase in speed cameras near schools when he appeared to become disoriented.
De Blasio stopped his remarks and turned to Nadler, offering him some water.
“Jerry, take a drink, you look a little dehydrated, brother. You seem a little dehydrated. You OK? ” de Blasio said. “Jerry? How you feel man? You all right?”
People started asking for a doctor and an announcement of a “code blue” was made over the public address system.
Doctors rushed to his side.
He seemed to recover his composure a short time later and was taken for a checkup.
“Appreciate everyone’s concern. Was very warm in the room this morning, was obviously dehydrated and felt a bit ill. Glad to receive fluids and am feeling much better. Thank you for your thoughts,” Nadler tweeted early in the afternoon.
“You can’t keep Jerry Nadler down,” tweeted de Blasio. “Thank you to the staff at PS 199 and NYC Health + Hospitals for their quick response.”
Nadler is the chairman of the House Judiciary Committee.