In fact, it is much more common than generally believed. It can occur along with any cause of sore nipples, but it may also, on occasion, occur without any other kind of nipple pain at all. Typically, Raynaud's phenomenon occurs after the feeding is over, once the baby is already off the breast. Presumably, the outside air is cooler than the inside of the baby's mouth. When the baby comes off the breast, the nipple is its usual colour, but soon, within minutes or even seconds, the nipple will start to turn white.
Mothers generally describe a burning pain when the nipple turns white.
Almost always, as the nipple soreness from another cause is getting better, so will the pain from Raynaud's phenomenon get better, but more slowly. However, some mothers no longer have pain during the feeding, or never had it at all. Indeed, some start having Raynaud's phenomenon during the pregnancy. If the pain is mild, there may be no reason to treat, and reassurance is all that is necessary. However, in some cases it is worth treating, especially if severe, and especially if the pain during the feeding does not improve, as severe restriction of blood supply to the nipple may delay healing.