What is flushing?
Flushing occurs because the blood vessels in the skin dilate. When flushing is produced by the 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.
- Food additives
- Neurological problems
- Other causes of flushing
- There is increased susceptibility to alcohol-related flushing in Asians, who have a defective enzyme (acetaldehyde 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 trichloroethylene 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 (potassium 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
Flushing associated with eating is very common.
- Hot beverages or food, or spicy food may cause flushing in otherwise normal individuals.
- The auriculotemporal syndrome 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 excessive salivation, tear production and nasal secretion with no history of parotid gland injury. This may be reproduced by chewing a chilli 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 due to embarrassment or anxiety
- Brain tumours
- 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 indomethacin)
- Amyl nitrite and butyl nitrite
- Cholinergic drugs
- Thyroid releasing hormone
- Cyproterone acetate
- Systemic steroids
Other causes of flushing
Rosacea is the most common skin condition that is associated with a tendency to flush easily. Other causes are listed below.
- Drinking Kava
- Scombroid fish poisoning results from bacteria acting on improperly refrigerated mackerel, tuna, and bonito 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
- Phaeochromocytoma (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.