When the tip of the nipple turns white and even deep purple, it's probably vasospasm, which is a spasm around the milk ducts squeezing out all the blood that can be very painful. (It's sometimes called Raynaud's Syndrome but that's usually a body-wide issue predating lactation.)
One quick tip to help the pain of it is to press blood into the tip of the nipple when it happens, which immediately stops the spasm and pain. A little milk might come out too and it won't cure the problem, but it can help in the moment.
Vasospasm typically happens from trauma to the nipple tissues, so the long-term treatment is to find out what is causing the trauma. It may be that you need a different flange size or if you're using either the pink or blue silicone flanges, the problem could be how they are being put on (see our Silicone Application Guide). Feel free to reach out to us for help from our inhouse lactation consultants.
Reviewed by Jenn Foster, IBCLC
January 26, 2022