Now, to use cajun spice as a substitute for paprika, add it gradually to your recipe. Make a taste test before adding more. I usually start with one-eight of a teaspoon for every teaspoon of paprika the recipe calls for.
On the other hand, paprika is much milder and the SHU ranges from 100-1,500 SHU, again depending on the variety of the plant it comes from. As far as the heat factor is concerned, the Indian red chili powder is much hotter than paprika.