This is for original Skyrim, as the Special Edition or mods can use other ingredients. I have only just begun to play the Special Edition, and I have no mods. I play on the XBox 360.
Ingredients for paralysis potions consist of two to three of any of the following ingredients: briar heart, canis root, swamp fungal pods, and imp stool. I use imp stool plus swamp fungal pod, or canis root plus imp stool, and NOT imp stool plus swamp fungal pod.
The reason is the last combination will make your potions less effective, basically adding health for your enemy when you use it on them. I generally don’t use briar heart, as they are much harder to obtain than the other ingredients.
Any way, before you make the potions, get your alchemy skill level up to 70. This will let you get the Concentrated Poison and Green Thumb perks. Green Thumb isn’t necessary, but you can get twice as much of each ingredient when you have it.
Once you have the Concentrated Poison perk at level 60, you can start making your paralysis potions. I have made my potions reach 15 to 16 seconds of paralysis. I think it can go even higher, but i’m not sure.
In future posts, I will explain where to best obtain your ingredients, and good ways to level up alchemy.