I get ALOT of people asking about Castor oil. This is why I am covering it here. 🙂
Castor oil, if you were to look it up, you would find that it is a plant oil. And we all know that a plant name with oil, gel or extract will block the Guaifenesin. So yes, Castor Oil will block the Guaifenesin from working.
Check out this post on salicylates!
Click for more on: Hydrogenated Oils can block!
Click for more info on: PEG 40 or 60 Hydrogenated Castor Oil