Flushing occurs because the blood vessels in the skin dilate. When flushing is produced by activity of the nerves to the blood vessels, it is accompanied by sweating. Agents which act directly on the blood vessels cause dry flushing.
Causes of flushing
Causes of flushing may be considered under the following headings.
- There is increased susceptibility to alcohol-related flushing in Asians, who have a defective enzyme (aacetaldehyde dehydrogenase) leading to a build-up of acetaldehyde.
- Tyramine or histamine in fermented alcoholic beverages (beer, sherry, wine) may induce flushing.
- Occupational ‘degreaser’ flush occurs in workmen drinking beer after exposure to industrial solvents, such as trichlorethylene vapour, N,N-dimethyl formamide, and N-butyraldoxime.
Some drugs cause flushing when the patient drinks alcohol. These include:
- calcium carbamide (urea)
- cephalosporin antibiotics
Alcohol may also cause flushing while mushrooms are consumed, and in patients with the rare tumour, carcinoid.
Flushing related to food additives
Flushing related to food additives is uncommon.
- MSG (Monosodium glutamate) (E621 and 622) in large doses may cause "Chinese restaurant syndrome."
- Sodium nitrite (and nitrates) (E249, 250,251,252) in cured meats, frankfurters, bacon, salami, ham, may cause headache and flushing in some people.
- Sulphites (potasssium metabisulfite) (E224), found in beer, cider, wine, desserts, fried and frozen vegetables, fruit juices, frozen prawns and shrimps, and milk products, may cause wheezing and flushing.
Note: E numbers are now on most NZ manufactured foods. However, fermented beverages, delicatessen food and restaurant food do not have to state additive content.
Flushing associated with eating is very common.
- Hot beverages or food, or spicy food may cause flushing in otherwise normal individuals.
- Auriculotemporal flushing refers to one-sided flushing, heat, and sweating following parotid gland injury or surgery.
- Gustatory flushing affects both sides of the face and is associated with excecssive salivation, tear production and nasal secretion with no history of parotid gland injury. This may be reproduced by chewing a chili pepper and holding it in the mouth for 5 minutes.
- Dumping syndrome is the association of facial flushing with racing heart, sweating, dizziness, weakness, and tummy upset. Symptoms begin after gastric surgery and are provoked after a meal or ingestion of hot drinks or strong glucose. The syndrome becomes worse after the menopause.
Neurologic flushing occurs in association with the following conditions.
- Simple blushing
- Brain tumors
- Spinal cord lesions
- Orthostatic hypotension
- Migraine headaches
- Parkinson disease
In susceptible individuals, the medications that may cause flushing include:
- All vasodilators
- All calcium channel blockers
- Nicotinic acid (flush may be blocked with aspirin or indometacin)
- Amyl nitrite and butyl nitrite
- Cholinergic drugs
- Thyroid releasing hormone
- Cyproterone acetate
- Systemic steroids
- Rosacea is a common skin condition that is often associated with or preceded by a tendency to flush easily.
- Drinking Kava
- Scombroid fish (mackerel, tuna, bonito) poisoning: results from bacteria acting on improperly refrigerated fish. Histamine forms in the flesh of the fish. Combined with a toxin known as saurine, it can, when ingested, produce:
- peppery taste
- mouth burning
- Carcinoid tumour with liver metastases (secondaries); flushing is due to circulating serotonin
- Phaechromocytoma (an adrenal tumour); flushing is due to circulating catecholamines (epinephrine/norepinephrine)
- Systemic mastocytosis; flushing is due to circulating histamine and is associated with low blood pressure (fainting) and breathing difficulties (bronchospasm).
Treatment of flushing
The treatment for flushing depends on the underlying cause.