I don't know if they work with certainty. I purchased a bunch of it a long time ago, right after the research about Ivermectin first came out. I've tried it but it makes you a little dizzy so you have to be careful with the doses. Well, it made me a little dizzy. I didn't know if I had COVID or not but wasn't feeling well so I thought I would try it. I still have about 10 bottles of oral tabs left they came from the pharmacy. Be careful if you use it I heard you needed large dosages for it to work against COVID but then I also heard it was making people sick and calling poison control centers. Personally, I would stay away from Ivermectin based on what I know.