That's an interesting question. I have pretty severe allergies. I also have asthma. I think they go hand in hand for me anyway because I can be healthy one day and down the next with what appears to be a cold, but it turns out to be an allergic reaction. I think they could suppress the immune system. In my case, I went for shots for a while and got sicker. Just my luck. So, that's what my take is anyway.