There are several possibilities for sudden dizziness, nausea and vomiting during breastfeeding. One is caused by postural hypotension, such as breastfeeding in the supine position, lying in bed and feeding. If you suddenly sit up or stand up, the change of position may cause postural hypotension, dizziness, blackness in front of the eyes, nausea and vomiting. So if you are lying on your back while breastfeeding, get up a little slower, don’t stand up or sit up violently, which can lead to a sudden change in position, causing a change in blood pressure, resulting in nausea and vomiting. If a patient has gestational diabetes or type 2 diabetes, hypoglycemia may occur due to lack of blood sugar control or excessive control, or if a patient takes insulin, hypoglycemia may occur due to excessive insulin injections, resulting in dizziness, nausea and vomiting, which is very dangerous. For patients with diabetes who take insulin, it is important to always have something to eat to avoid hypoglycemia, as it can be life-threatening. Other causes may be hypertension. In case of hypertension during pregnancy, patients who are breastfeeding may still have elevated blood pressure. A sudden or continuous increase in blood pressure can also lead to dizziness, nausea and vomiting, so blood pressure monitoring should be performed.