Bell's palsy has been linked to stress, although a precise cause has not been found. Conditions such as hypertension (high blood pressure), diabetes, Lyme disease and autoimmune disorders, chronic ear infections, tumors and trauma to the head or face have also been identified as coinciding with the illness.

According to John Hopkins Medicine, Bell's palsy is "an unexplained episode of facial muscle weakness or paralysis. It begins suddenly and can get worse over 48 hours. This condition results from damage to the facial nerve (the 7th cranial nerve). Pain and discomfort usually occur on one side of the face or head."