Have any of you ever used one and if so did it work well?

My hubby and one of my son's suffer from terrible allergies that have gotten so much worse since we moved into our current rental house. I am trying to find something that will help other than moving.

Thanks! 

I had really bad allergies when I was younger. My parents bought one, as the doc recommended, and it worked great. Just make sure to do some research on brands and areas they cover. 

We have one.I have to have something to keep the dust out. The purifier we have works very well. 

LaLa Yes, air purifiers do work. We've got three to cut down on animal hair.
But if your son has severe allergies, you need to make sure you live in a place that doesn't have carpets or curtains. You need to wash floors every day and might also need to use humidifier along with an air purifier.
Air purifier alone won't make too much of a difference. 

Thanks everyone!