How often you boil rearz nipples?

How often you boil your rearz nipples?and how often do u replace them? My psw says she throws out her sons nipples every 3 months.

I only wash them when I wash the bottle. I do know you don’t want to run them in the dishwasher. The heat ruins the mopped.

Ya I wash them or better say my psw. That why I'm asking she ask me when do I want to boil to sanitize them and second on the rearz web site say ok to boil. Try looking up but keep used in baby bottle. Lol