[1][2] The symptoms of Frey's syndrome are redness and sweating on the cheek area adjacent to the ear (see focal hyperhidrosis).

[2] Signs and symptoms include erythema (redness or flushing) and sweating in the cutaneous distribution of the auriculotemporal nerve, usually in response to gustatory stimuli.

[2] It is often seen with patients who have undergone endoscopic thoracic sympathectomy, a surgical procedure wherein part of the sympathetic trunk is cut or clamped to treat sweating of the hands or blushing.

Rarely, Frey's syndrome can result from causes other than surgery, including accidental trauma, local infections, sympathetic dysfunction, and pathologic lesions within the parotid gland.

[5] Cochrane reviews of interventions to either prevent[7] or treat[8] Frey's syndrome have found little or no evidence to support their effectiveness or safety, and conclude that further clinical trials are needed.