Sudden enlargement of the areola may be caused by puberty development, pregnancy, breast allergy, breast fibroadenoma and so on. 1. Pubertal development: During the period when the breasts start to develop, the nipple and areola will keep getting bigger, which is a normal physiological phenomenon. 2. Pregnancy: After pregnancy, due to the change of estrogen in the body, it will promote the nipple and areola to become bigger, which is a normal phenomenon. 3. Breast allergy: when the patient’s breasts come into contact with poor-quality underwear or cream, it may cause allergy, resulting in the areola will be enlarged, painful phenomenon. If other adverse reactions occur, it is recommended that the patient go to a regular hospital in time, under the diagnosis of the doctor, according to the patient’s specific condition, to take targeted treatment.