Frey's syndrome is a rare complication of surgery or an injury of one of two glands in the cheek that make spit, also known as parotid glands. Other glands that make spit, also known as salivary glands, are in the lips, mouth and throat. The parotid glands sit in front of the ears on each side of the face.

Symptoms include sweating and flushing on the cheek or temple, or behind the ear. Foods with stronger flavors, such as sour, spicy or salty foods, might be more likely to cause symptoms.

Many treatments have been tried, including using antiperspirant on the affected area and surgery. But treatments don't often work well.