Ways to remove stain

Looks like it's been like that for very long. Best to throw and get a new one. I suggest when you get a new one, you hvta wash the teat separately and dry properly before you put it in bck to the rim so that it wont mould that fast. But once it starts to mould even one spot, you need to change already.

would suggest you get a new one. it looks like mould to me. remember to soak in hot water occasionally to prevent these to happen.

Please throw away and replace with new one. To prevent it, you may want to soak in hot water after each use.

I will not suggest to remove the stains but to buy a new one. This may have bacteria and will affect your lo.

Better to get a new one .. I won’t risk the bacteria that my baby will get if I use this.

This is probably mould. Just dump and get new teats.

Better to change to new ones

Following for suggestions

best to buy a new one...

Get a new teats mummy.