I've played for quite some time now, and I've found only two red mutagens so far, both are named ones and not the generic red mutagens. I've at least a dozen of the green and blue mutagens lying around.
Where can I get some more red mutagens from?
3 Answers
According to this wiki, they drop from the following monsters:
Archgriffin, Doppler, Katakan, Greater Foglet, Nekker Warrior, Water Hag, Wyvern, Succubus, and Werewolf
As you can see, they aren't the most common monsters, which is likely why you don't have as many as blue or green. This link has a couple farming locations.
I've gotten a Red Mutagen from a Warrior Nekker
But I'm just like you I come across a lot of blue and green ones. But dropped on me a red one from killing a Warrior Nekker in Velen
I found a-lot of them in Skellige fighting different monsters.
