Firstly described by Lucy Frey in 1923 the “Frey’s syndrome” is characterized by sweating and flushing in direct response to mastication. The mechanism is aberrant regeneration of postganglionic parasympathetic neurons from the auriculotemporal nerve and Acetylcholine secretion by a masticatory stimulus. This entity occurs in up to 65% following lateral parotid resections and less commonly after neck dissection or facelift procedures. This article aims to list possible surgical and non-surgical treatment options of this iatrogenic entity but should focus on the treatment with botulinum toxin A and provide a step by step guide from the Lugol-Iodine-Starch test to the botulinum toxin A (BoNTA-ONA) injection within the affected area.