If you have a swollen face, it may be caused by myxedema, one of the more common hypothyroidism symptoms.¹

Hypothyroidism causes an increased amount of water in your skin and a loosening of your collagen. This is due to a buildup of mucopolysaccharides, a type of amino sugar that attracts water and causes the collagen in your skin to separate. Your body's metabolism slows down when your thyroid gland is not working properly.^1,2

A slow metabolism creates less heat and drops your core body temperature. Your veins then constrict and become less elastic in response, leading to water and salt retention. This is why a swollen face can present itself as one of many hypothyroidism symptoms.²

If you are experiencing swelling in your face, it is recommended to speak to your doctor about testing your thyroid.