Menopausal flushing
Emotional flushing
Alcohol intake.
Rosacea
Drugs: calcium-channel blockers, nicotinic acid, levodopa, etc)
Certain Foods: spicy foods, cured meats, monosodium glutamate
Carcinoid syndrome; VIPoma
Hyperthyroidism.
Pheochromocytoma.
Cluster headache.
Migraine
Serotonin syndrome.
MAO deficiency causing elevated serotonin.
Dumping syndrome
Anaphylaxis
Bronchogenic carcinoma
Sarcoidosis
Systemic Mastocytosis
Medullary thyroid carcinoma
Pancreatic cell tumor,
Renal cell carcinoma,
Auriculotemporal Nerve Syndrome (Frey’s Syndrome)
Harlequin Syndrome
Androgen deficiency in men; Secondary Male Hypogonadism
CNS tumor
Autonomic epilepsy
Spinal cord injury
Parkinson disease
Multiple sclerosis
Autonomic hyperreflexia/orthostatic hypotension
Trigeminal neuralgia
Physiologic or Thermoregulatory flushing: Fever, Exercise, Exposure to heat, hot drinks (e.g. hot coffee/tea); Embarrassment or anger.

Thinking through the differential diagnosis.
The DDx can be divided into vasodilator-mediated flushing vs. Autonomic mediated flushing
Further Reading
J Am Acad Dermatol. 2006 Aug;55(2):193-208. https://www.ncbi.nlm.nih.gov/pubmed/16844500
http://www.clevelandclinicmeded.com/medicalpubs/diseasemanagement/endocrinology/flushing/ (Last Accessed in December 2017)

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