Is using a nipple guard bad?

I use a nipple guard everytime I breastfeed. I have extremely sensitive nipples already and using the nipple guard helps me feel like I can actually stand to feed him everytime he's hungry. I've never not used it but I'm honestly scared to death. I don't think I'll be able to handle it and I love breastfeeding so I don't want to give it up. He definitely gets enough to eat but I feel like it's a big no no in breastfeeding..?