What causes armpit pain during breastfeeding?

Axillary pain during lactation is usually caused by acute mastitis, which is more common in lactating women, especially among primiparous women who are more prone to fever and have a history of cracked and broken nipples and poor milk retention before the onset.
To prevent acute mastitis, patients are advised to avoid milk stagnation and, at the same time, to prevent nipple damage and maintain breast hygiene.