Sweet paprika measures 500 to 1,500 Scoville heat units, making it a very mild pepper indeed. Hotter varieties of paprika can approach 30,000 to 50,000 heat units, which is basically equivalent to pure cayenne pepper. So if your recipe explicitly calls for hot paprika, you could substitute cayenne pepper.
Those who love Korean cuisine probably already know this next backup. Gochugaru powder is better known in the US as ground Korean chili powder. This famous Asian condiment is loved for its sweet and spicy taste with a subtle smoky note, making it a nice paprika alternative. It’s also prized for its color which adds a bright red hue to dishes like tteokbokki (Korean spicy rice cake) and yukgaejang (spicy beef soup).