It's always hard to tell when vitamins or things like that work because usually you don't feel any different but you just know they are providing you with intrinsic benefits. I have been taking Thymuplex since July and have not had a cold, avoided the swine flu, and the normal flu even though it has been around my office and friends. I started taking it because I was diagnosed with lo-risk HPV. A way of fighting that is building your immune system. While treatments and medications have made no progress with my HPV, I still feel like I have felt great and have avoided getting easy to catch sickness' and virus. So I give it a thumbs up!