The league's department of player safety issued the ruling Thursday, while Toronto prepares to play at Buffalo. The hit occurred a day earlier in the third period of Toronto's 4-2 win.
Shortly after Hedman passed the puck in the neutral zone, Lupul left his feet while lunging into Hedman from the side. Lupul's lower left shoulder struck Hedman in the side of the head.
Lupul was issued a minor penalty for the hit. Hedman returned after briefly leaving the game.
The NHL ruled further discipline was necessary because Lupul targeted Hedman's head.
The suspension will cost Lupul about $46,000 in salary.