A. Case study
B. More information
C. Editors' comments
D. References
E. CPD questions (South Africa, Australia



A. Case study

A 5-month-old boy presented with red blotches on the left side of his face, extending from the corner of his mouth to a little past the ear. The blotches were not raised or swollen. The mother described the reaction as starting close to the ear and spreading in the direction of the mouth. The "rash" did not seem to itch or burn (the child did not try to scratch the area), and the area was also not flaky. The rash would appear within minutes after the child had 2 or 3 teaspoons of certain foods and would disappear within an hour.

The mother had introduced solid foods into her son's diet at 4 months of age. While still breastfeeding, she started him on rice cereal, maize cereal and then commercial bottled fruit and vegetables. This is when the rash started appearing. She decided to discontinue the bottled food and give him fresh fruit and cooked vegetables instead of the commercial ones. The reaction still occurred. Food allergy was suspected.

The foods that the boy was reacting to were commercial "Butternut," "Carrots" and "Peaches and Apples." Also problematic were fresh mashed banana, fresh mashed mango, cooked plain potato and cooked plain sweet potato. He did not react to rice cereal, maize cereal, cooked plain gem squash, ice cream, dried meat (biltong/jerky), softdrinks or rooibos tea.

His condition was duly distinguished from angiomas (localized vascular lesions of the skin or subcutaneous tissues) that may be present in infants. Angiomas are persistent red rashes or blotches, e.g., nevus flammeus (also known as port-wine stain) and capillary hemangioma (also known as strawberry mark).

There were many possible causes, including:
a. He was reacting to contact with the spoon, e.g., nickel allergy.
b. He was reacting to a substance that was added to the food. This could have been among commercial additives, or it could have been any substance (such as a flavouring) that the mother added to the food.
c. He was experiencing heat-induced urticaria, i.e., he would get a reaction when in contact with a hot substance, in this case, food.
d. He was experiencing dermatographism (a form of urticaria in which whealing occurs on the site and in the configuration of the application of pressure or friction to the skin.
e. He was reacting to something else in the environment that was coincidentally present every time he was eating.

a. The same spoon was used when giving the boy the foods that he reacted to as the foods that he did not react to. If it was nickel allergy, for example, the rash would be constant.
b. The food was given to the child in a pure state. Nothing was added to it. The commercial foods did not contain any additives.
c. All foods were given at room temperature. The mother waited for cooked foods to cool before feeding her son.
d. Dermatographism was excluded.
e. Nothing relevant could be identified.

Conditions such as contact allergy, oral allergy syndrome and other physiological or chemical causes needed to be excluded. Other questions to be asked at this point:
a. Was he reacting to contact with the food?
b. Was he reacting to contact with a cloth, treated with a chemical, that the mother used to wipe food off his cheek?
c. Was he experiencing any other types of reactions?
d. Was the mother giving the foods one at a time, or some together?
e. Was the reaction consistently associated with a specific food?
f. Did he ever experience a reaction at a time other than while eating?
g. Was there a relationship between the foods that he reacted to, i.e., a family relationship or a common allergen present?

a. When eating, the boy would get food all over his face, but the rash would consistently appear in the same area.
b. The face cloth that was used was not treated with any chemicals and was used on other parts of his body as well.
c. The boy did not have any symptoms other than the red blotches, such as angioedema. He also did not complain when eating any of the food. He was actually a good eater.
d. All foods were given one at a time, as the mother was trying to identify a possible cause herself.
e. He reacted to most foods every time he ate them. With others, he did not consistently experience a reaction.
f. The rash had only appeared while eating.
g. No family, allergen or chemical relationship between the foods that affected the child could be identified.

Thus far, it could be established that the boy reacted to foods that have no relation to each other; that he did not react to a certain food every time; that the only reaction he got was a rash on a specific area on his face; that the reaction only occurred while eating; and that it did not produce discomfort in the child.

Could it be oral allergy syndrome? This syndrome is a combination of oral symptoms (including a swollen and itchy mouth and throat), and a concominant sensitivity to pollen. What about allergy-associated acute urticaria? This is also usually itchy, with raised lesions that do not appear in the same area of the skin every time; they seem to migrate without a fixed pattern. Also, with an allergy, one would expect the child to react consistently to the same amount of food prepared in the same way.

In this case, the diagnosis was Frey's syndrome. Frey's syndrome is a disorder characterized by recurrent episodes of localized facial flushing and/or sweating in the area anterior to the ear and on the cheek, in response to gustatory stimuli. The symptoms are typically unilateral. In infancy this syndrome is a benign condition that often resolves spontaneously. Treatment is usually unnecessary and often ineffective anyway.

What points should have immediately diverted the health professional from suspecting food allergy as a cause? The rash was always in the same location, occurred in the absence of other symptoms such as edema or itching, resolved quickly, and occurred on challenge with a variety of unrelated foods.

TIP for Allergy Advisor users:
If one is unsure of the type of reaction that the patient is experiencing, the "Photos & Images" and "Glossary" functions can be very useful. The "Photos & Images" contains a database of photos of, amongst others, clinical images where one will be able to compare clinical images with the symptoms of a patient. The "Glossary" gives descriptions of allergy related conditions and terms. In this case, where urticaria was suspected at first, the glossary would describe the typical presentation of urticaria as different from what this patient experienced.

If one is not certain that the patient has an allergy, one can find a list of information pieces on differential diagnosis of allergy under the "Assessment" section of Allergy Advisor. E.g., differential diagnosis of adverse reactions to food, differential diagnosis of exercise induced anaphylaxis, differential diagnosis of unexplained flushing/anaphylaxis and the classification and diagnostic evaluation of urticaria.

B. More information:

The first case of gustatory sweating (see below) was described in 1757 by Duphenix, but it was not until 1923, when Lucja Frey started doing research into this syndrome, that the term Frey's syndrome came about.1

What is Frey's syndrome?

Frey's syndrome (FS) is characterized by recurrent episodes of localized facial flushing and/or sweating in the cutaneous distribution of the auriculotemporal nerve (i.e., the area anterior to the ear and on the cheek).2 This usually occurs in response to gustatory (taste) or occasionally tactile (touch) stimuli3,4,5 and usually becomes apparent within a few seconds of eating and subsides within minutes (or longer in some cases: up to 1 hour has been reported) after discontinuing the food.6 It has also been termed auriculotemporal or gustatory sweating syndrome.7 The symptoms are typically unilateral,4,7 although a couple of bilateral cases have been reported.8

This reaction, which occurs immediately after the ingestion of food and involves a rash, can easily be interpreted as a food allergy.3,9 It is therefore important for health professionals to be familiar with this condition, in particular because of our increased awareness of oral allergy syndrome (this topic will be discussed in a future newsletter), so that unnecessary testing and delay in diagnosis do not occur.3,4

What is the mechanism involved?
The pathophysiology of the syndrome is not completely understood, but there are some theories. The auriculotemporal nerve contains afferent sensory fibers from the skin, and also contains efferent fibers, which include secretory sympathetic fibers attached to sweat glands, sympathetic vasodilatory fibers attached to subcutaneous vessels, and parasympathetic vasodilatory fibers attached to the parotid gland.9 If the nerve is injured, misdirection may occur as the regenerating fibrils join the distal sympathetic fibers. These fibers innervate the sweat glands and subcutaneous vessels. Subsequently, chewing may activate the sweat glands and subcutaneous vessels instead of the fibers that carry impulses to the salivary gland.4,10,11 In other words, as the affected person starts eating, facial flushing and/or sweating occur instead of the normal production of saliva from the parotid gland.12 Some patients describe a subjective sensation of warmth in the involved area while eating, and objective sensory deficit in the involved area is common.13

It is quite common in adults as a result of surgery, trauma or disease of the parotid gland area,13 but is uncommon in children. In children, FS generally presents before the age of 1 year, and it is most commonly first noticed when solid foods are introduced into the diet. The reason for FS not to be associated with breastfeeding or taking formula is possibly that chewing, particularly the more vigorous chewing of favorite foods, elicits a more intense stimulation of the parotid gland than does the sucking of fluids.3,4,12,14,15

There is some evidence suggesting that local trauma to the parotid area during delivery may be responsible for damage to the auriculotemporal nerve in children. About 50% of infants with FS described in the literature were delivered with the aid of forceps. In only 7.5% of overall deliveries are forceps used, which suggests a more than coincidental relationship. In cases with no known trauma to the parotid area, the mechanism is thought to be a congenital aberrant nerve pathway.2,14,16

FS has also been described in some children with epilepsy and diverse other early childhood diseases of the central nervous system.6

Older children may also experience gustatory sweating, especially after suppurative parotiditis6 and accidental trauma.2 In contrast to adults and older children, in infants and younger children it is exceptional to have sweating (they generally only have flushing) and bilateral involvement.2,3,5,14 In adults, gustatory sweating is the predominant feature of this syndrome, and flushing may be associated.3

Adult FS is usually a consequence of a parotidectomy (surgical removal of the parotid gland). The literature has indicated that FS develops postoperatively in 13-60% of patients undergoing paritodectomy17 and that the incidence in patients not undergoing intraoperative preventive measures is 96%. Most patients with FS have only mild to moderate symptoms (only 6% of patients experience severe symptoms). FS may also occur after other surgical, traumatic and even inflammatory injuries of the parotid or submandibular glands and of the cervical and upper thoracic portions of the sympathetic trunk.3,4,7,16,17

FS may appear only years after the injury.7 In most cases this interval ranges from 2 weeks to 2 years (but there has been a report of 8 years passing before symptoms were first experienced).7 This is probably related to the time required for nerve regeneration.3

Types of gustatory sweating:
Several gustatory sweating syndromes are described in the literature. Gustatory sweating syndromes can be either congenital or acquired in origin and can be either physiological or organic. Most have clearly defined precipitating events, the commonest of which is trauma. Spontaneous gustatory sweating syndromes have also been reported.18

The different types identified include the following:

  • Occurring in uniquely hot and humid climates, of a mild degree and symmetrically distributed over the face and neck.

  • Following surgery, trauma or inflammation of the parotid or salivary glands; i.e., auriculotemporal or Frey's syndrome. The sweating is usually unilateral, involves the face anterior to the ear (which is served by the auriculotemporal branch of the facial nerve), and may be accompanied by flushing.

  • As a complication of diabetic autonomic peripheral neuropathy, in which the sweating is usually bilateral and involves the head and neck.

  • As a complication of thoracic ganglionectomy (removal of the an autonomic or sensory ganglion).

  • Idiosyncratic, brought on by one or a few specific foods such as chocolate or cheese. The sweating is bilateral, involving the face and neck, and is often accompanied by flushing.19,20,21
  • How is it treated?
    Various treatments have been suggested for adults, including atropine, antihistamines, surgical resection of the auriculotemporal nerve, botulinum toxin, infrared thermography and scopolamine salve.4 Such treatments have often proved ineffective and sometimes even produced significant morbidity.2,12

    Although these treatments may be effective in some adult patients, no specific therapy is recommended for this condition in children,4 as the condition is considered to be a benign one that often resolves spontaneously. Treatment is ineffective and unnecessary.3,9

      compiled by Karen du Plessis B.Sc. Diet.
    Food & Allergy Consulting & Testing Services (FACTS)
    PO Box 565
    Milnerton 7435
    South Africa

    C. Comments by our editor

    Prof Janice M. Joneja Ph. D., RDN
    This is an excellent example of applying the first law of food allergy practice: rule out any other pathology before considering food allergy as the cause of the condition. Symptoms typical of food allergy are sometimes part of a pathology that has a cause quite distinct from adverse reactions to foods. Because so many people - the general public as well as clinicians and health care personnel - are very well informed about food allergy, thanks to a significant increase in reports in medical journals and articles in popular magazines, food allergy is often the first thing that comes to mind when symptoms such as those discussed in this case study are presented. However, until definitive diagnostic tests for food allergy are available, it will tend to remain a diagnosis of exclusion; that is, rule out any other etiological factors first, and then consider food allergy as the cause of the patient's symptoms.

    For more information on this subject and other allergy and intolerance related topics, visit:

    To join a professional food allergy discussion list where this subject can be discussed further, go to or

    We invite you to send us interesting case studies. We pay US$100 for each case study we use in our newsletter.

    To subscribe or unsubscribe, send an e-mail to info@zingsolutions.comand put "subscribe Educational" or "unsubscribe Educational " as the subject.

    D. References
    1. Hennon DK. Facial flushing in children: a variant of the auriculo-temporal syndrome. J Indiana Dent Assoc. 1991 Jan-Feb;70(1):25-7.
    2. Kaddu S, Smolle J, Komericki P, Kerl H. Auriculotemporal (Frey) syndrome in late childhood: an unusual variant presenting as gustatory flushing mimicking food allergy. Pediatr Dermatol. 2000 Mar-Apr;17(2):126-8.
    3. Dizon MV, Fischer G, Jopp-McKay A, Treadwell PW, Paller AS. Localized facial flushing in infancy. Auriculotemporal nerve (Frey) syndrome. Arch Dermatol 1997 Sep;133(9):1143-5.
    4. Karunaanthan CG, Kim HL, Kim JH. An unusual case of bilateral auriculotemporal
    syndrome presenting to an allergist. Ann Allergy Asthma Immunol 2002;89:104-5.
    5. Moreno-Arias GA, Grimalt R, Llusa M, Cadavid J, Otal C, Ferrando J. Frey's syndrome. J Pediatr. 2001 Feb;138(2):294.
    6. Beck SA. Auriculotemporal Syndrome Seen clinically as Food Allergy. Pediatrics 1989; 83: 601-3.
    7. Malatskey S, Rabinovich I, Fradis M, Peled M. Frey syndrome--delayed clinical onset: a case report. Oral Surg Oral Med Oral Pathol Oral Radiol Endod. 2002 Sep;94(3):338-40.
    8. Johnson IJ, Birchall JP. Bilatral auriculotemporal syndrome in childhood. Int J Pediatr Otorhinolaryngol 1995 Apr;32(1):83-6.
    9. Sicherer SH, Sampson HA. Auriculotemporal syndrome: a masquerader of food allergy. J Allergy Clin Immunol. 1996 Mar;97(3):851-2.
    10. Du Toit DF. Auriculo-temporal nerve. Clinicopathological relevance to facial-maxillary practice. SADJ. 2003 Mar;58(2):62-3.
    11. Dunbar EM, Singer TW, Singer K, Knight H, Lanska D, Okun MS. Understanding gustatory sweating. What have we learned from Lucja Frey and her predecessors? Clin Auton Res. 2002 Jun;12(3):179-84.
    12. Kozma C. Gustatory flushing Syndrome. Clinical Pediatrics 1993; 629-631.
    13. Harper KE, Spielvogel RL. Frey's syndrome. Int J Dermatol 1986; 25: 524-6.
    14. Rodriguez-Serna M, Mari JI, Aliaga A. What syndrome is this? Auriculotemporal nerve (Frey) syndrome. Pediatr Dermatol. 2000 Sep-Oct;17(5):415-6.
    15. Sampson HA. Diferential diagnosis in adverse reactions to food. J Allergy Clin Immunol 1986; 78: 212.
    16. Reche Frutos M, García Ara MC, Boyano T, Díaz Pena JM. Syndrome auriculotemporal. Allergol Immunopathol 2001; 29: 33 - 34.
    17. Teague A, Akhtar S, Phillips J. Frey's syndrome following submandibular gland excision: an unusual postoperative complication. ORL J Otorhinolaryngol Relat Spec. 1998 Nov-Dec;60(6):346-8.
    18. Sonsale A, Sharp JF, Johnson IJ. Gustatory sweating of the external auditory canal. J Laryngol Otol 1999 Nov;113(11):1000-1.
    19. Sheehy TW. Diabetic gustatory sweating. Am J Gastroenterol 1991 Oct;86(10):1514-7.
    20. Freeman GL. Gustatory sweating in the differential diagnosis of food allergy. Allergy Asthma Proc. 1998 Jan-Feb;19(1):1-2.
    21. Blair DI, Sagel J, Taylor I. Diabetic gustatory sweating. South Med J. 2002 Mar;95(3):360-2.

    E. CPD Questions (For South African dietitians only. Australian dietitians: where you have relevant learning goals, CPD hours related to this resource can be included in your APD log.)

    You can obtain 2 CPD points for reading this newsletter and answering the accompanying questions. This newsletter with questions has been accredited for dietitians.
    CPD reference number: DT03/3/081/13

    1. Complete your personal details below.
    2. Read the newsletter and answer the questions.
    3. Indicate your answers to the questions by making a "X" in the appropriate block.
    4. You will earn 2 CPD points if you answer more than 75% of the questions correctly. If you score is between 60 and 75%, 1 CPD point will be allocated. A score of less than 60% will unfortunately not earn you any CPD points.
    5. Make a photocopy for your own records in case your answers do not reach us.
    6. Cut and paste the area indicated below into a e-mail message and e-mail it to to be received no later than 30 September 2003. Answer sheets received after this date will not be processed.

    (There is only one correct answer per question.)
    1. Which of the following is not true regarding Frey's syndrome?
    (a.) It tends to occur only on one side of the face.
    (b.) It can involve both flushing and sweating.
    (c.) It can appear only once.
    (d.) It occurs in response to gustatory stimuli.

    2. True or false: Frey's syndrome is more common in infants than in adults.
    (a.) True
    (b.) False

    3. Frey's syndrome can be caused by which of the following?
    (a.) Surgery, trauma or disease of the parotid gland area
    (b.) Surgical, traumatic or inflammatory injuries of the cervical and upper thoracic portions of the sympathetic trunk
    (c.) Delivery aided by forceps
    (d.) All of the above

    4. In children, Frey's syndrome generally presents before what age?
    (a.) 1 year
    (b.) 4 months
    (c.) 6 months
    (d.) 10 years

    5. True or false: Infants and younger children with Frey's syndrome generally only have flushing, compared to adults, in whom gustatory sweating is the predominant feature.
    (a.) True
    (b.) False

    6. The literature has indicated that Frey's syndrome develops postoperatively in which percentage of patients undergoing paritodectomy without intraoperative preventive measures?
    (a.) 6%
    (b.) 13-60%
    (c.) 50%
    (d.) 96%

    7. True or false: Frey's syndorme may appear only years after the injury.
    (a.) True
    (b.) False

    8. Which of the following is true regarding the treatment of Frey's syndrome?
    (a.) It is very effective in adults.
    (b.) It is very effective in children.
    (c.) No side effects have been reported.
    (d.) No specific therapy is recommended for children.

    Cut and paste this section below into an e-mail message

    Frey's syndrome
    CPD Reference number: DT03/3/081/13

    HPCSA number: DT
    Surname as registered with the HPCSA:
    E-mail address:

    Please make an "X" in the appropriate block for each question

    1. a [ ] b [ ] c [ ] d [ ]   2. a [ ] b [ ]   3. a [ ] b [ ] c [ ] d [ ]
    4. a [ ] b [ ] c [ ] d [ ]   5. a [ ] b [ ]   6. a [ ] b [ ] c [ ] d [ ]
    7. a [ ] b [ ]   8. a [ ] b [ ] c [ ] d [ ]