The legalities depend a lot on where you are and what your local/national laws say. In the U.S., for example, the law's much stricter for things that need a doctor's prescription and have to be dispensed by a licensed pharmacist. I have no idea how pheromones fit into that - in the U.S. or anywhere else! You'd need to check with someone who's an expert on your local laws.
For your own peace of mind, you'd probably also want to know how close the ties are between the affiliate network and the "pill sites". Read the affiliate agreement closely to be sure that you have complete control over what your site advertises, and that the network doesn't have the option of substituting something else under any circumstances. You shouldn't have to advertise anything you don't want to.
You should check the terms of reference and legal sections of the other major sites that promote these pills - that will give you a decent handle on the legality.
But the simplest thing to do is get a written disclaimer from the actual seller of the pills or the affiliate middle-man that accepts that the responsibility for the legality of selling the pills is theirs and not yours.