Frey syndrome classically causes gustatory sweating and facial flushing. We describe 2 cases in which medical thermography was used to investigate the symptoms. Images were taken after patients chewed a sialagogue and 2 weeks later they were given injections of botulinum toxin A. Images taken 4 weeks after treatment showed a considerable reduction in sweating and facial flushing, which was supported by the results of quality of life questionnaires completed before and after treatment. Medical thermography is much cleaner than the Minor's starch iodine test. It identifies areas of gustatory sweating, changes in temperature, and vascular changes, which potentially enable treatment to be targeted accurately.