Frey’s Syndrome

Frey’s syndrome happens when you experience facial sweating and flushing when you eat. It’s often a side effect of parotid gland surgery and happens due to nerve damage and abnormal nerve regrowth. Botox® injections can help manage the sweating.


What is Frey’s syndrome?

Frey’s syndrome is a rare neurological condition that causes you to sweat excessively while eating or thinking about food. You sweat on your cheek, temple and/or behind your ear (not your whole body). You may also get flushing (redness or discoloration) in these areas.

Frey’s syndrome most often develops as a side effect of surgery — typically, those related to your parotid glands. These glands are the largest salivary (spit) glands in your body. They’re just below and in front of your ears on either side of your face. Your parotid glands produce spit to keep your mouth lubricated and to aid in chewing and digestion.

Other names for Frey’s syndrome include:

  • Auriculotemporal nerve syndrome.
  • Gustatory sweating.
  • Gustatory hyperhidrosis.
  • Baillarger’s syndrome.
  • Dupuy syndrome.

The condition is named after Lucja Frey, a neurologist from Poland who accurately identified it in 1923.

How common is Frey’s syndrome?

Researchers don’t know how common Frey’s syndrome is due to inconsistencies in reporting it. Some studies suggest that 30% to 50% of people develop the syndrome after a parotidectomy (surgical removal of a parotid gland).


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Symptoms and Causes

What are the symptoms of Frey’s syndrome?

The main symptom of Frey’s syndrome is excessive sweating (hyperhidrosis) when you eat or think about food for a long time. This is called gustatory sweating. You sweat on your:

  • Cheek.
  • Temple.
  • Around your ear.

You may have flushing and feel warmth in these areas, too.

The sweating and flushing can range from mild to severe. Foods that have a strong salivary response, like sour, spicy or salty foods, may make you sweat more.

The symptoms of Frey’s syndrome typically develop within the first year after surgery in the area near your parotid gland(s). But some people don’t develop symptoms until several years after surgery.

What are additional negative effects of Frey’s syndrome?

The symptoms of Frey’s syndrome are usually mild. But severe sweating can cause significant discomfort or social anxiety. If excessive sweating when you eat is causing distress, talk to a healthcare provider and/or a mental health provider, like a psychologist.

What causes Frey’s syndrome?

Scientists don’t know the exact cause of Frey’s syndrome. Their main theory is that it happens due to simultaneous damage to sympathetic and parasympathetic nerves near your parotid gland.

Your parasympathetic nervous system (PSNS) and sympathetic nervous system (SNS) are part of your autonomic nervous system (ANS). Your ANS is responsible for many functions that you don’t have to think about to control, like your heart rate and digestion.

One function of parasympathetic nerves is to regulate your salivary gland activity, including your parotid glands. But your PSNS doesn’t control sweat gland activity. Your SNS does that.

Researchers think that Frey’s syndrome happens when the parasympathetic and sympathetic nerves near your parotid glands are damaged at the same time.

Normally, tiny nerve fibers can heal themselves and grow back. In Frey’s syndrome, scientists think that damaged parasympathetic nerve fibers grow back abnormally along the sympathetic fiber pathways. These connect parasympathetic nerves to the sweat glands on your skin.

Because of this abnormal “rewiring,” the parasympathetic nerves that normally signal your parotid glands to produce spit in response to tasting now respond by telling your sweat glands to produce sweat.

This results in profuse sweating while you eat. Sympathetic nerves also control your blood flow by constricting or widening (dilating) blood vessels. This is why Frey’s syndrome can also cause flushing in the affected areas.

It takes time for your nerves to grow back after they’re damaged. This is probably why Frey’s syndrome typically develops six to 18 months after surgery.

Surgeries that can cause Frey’s syndrome

Frey’s syndrome most commonly develops from accidental nerve damage during a parotidectomy. But the following surgeries or injuries can also cause it:

  • Submandibular gland surgery.
  • Surgical repair of a broken jaw (mandibular fracture).
  • Temporomandibular joint injury.
  • Neck lymph node removal surgery (dissection).
  • Trauma to the parotid region.

Diagnosis and Tests

How is Frey’s syndrome diagnosed?

To help diagnose Frey’s syndrome, your healthcare provider will ask about your symptoms and when they started. They’ll also ask about your medical history and if you’ve had any surgeries on or injuries to your face.

A definitive way to diagnose Frey’s syndrome is with a Minor starch-iodine test. The steps of this test include:

  1. Your provider will brush iodine on the affected areas of your face.
  2. Once it’s dry, they’ll apply starch (like corn starch) over the area.
  3. You’ll eat something to stimulate your salivary glands — usually something sour, like sour candy or a lemon wedge.

If you start to sweat, the starch will become moist and turn blue or brown. This confirms Frey’s syndrome.


Management and Treatment

How is Frey’s syndrome treated?

There’s no cure for Frey’s syndrome, so treatment mainly involves managing symptoms. If your symptoms are mild, you may not want to try treatments. But for those who have severe symptoms, some methods to manage sweating include:

  • Botox® (botulinum toxin) injections: Healthcare providers most commonly use Botox injections to manage gustatory sweating. It temporarily damages your sweat glands near the site of the injection. Most people who get the injections report an improvement in gustatory sweating, flushing and overall quality of life. The effect wears off over time — usually after nine to 12 months — so you’ll likely need repeated injections.
  • Topical anticholinergics: These medications work by reducing the activity of your sweat glands. They’re effective, but you have to apply them to your skin frequently.
  • Topical antiperspirants: Topical antiperspirants (like certain deodorants) may help control sweating, but their effects are mild. Like topical anticholinergics, you have to apply them frequently.

In rare cases in which these methods haven’t helped, healthcare providers may recommend surgery. It involves cutting certain nerves. There are several types of surgery.


Can I prevent Frey’s syndrome?

There’s nothing you can do to prevent Frey’s syndrome. Surgeons try to use certain techniques to prevent damaging nerves during facial surgeries. But these techniques aren’t always an option. They all have associated risks and disadvantages, like:

  • Prolonged operating time.
  • Varying effectiveness in preventing Frey’s syndrome.
  • Wound infection.
  • Postoperative complications.

Your surgeon will discuss any risks, side effects or possible complications with you before the surgery. Don’t hesitate to ask them questions or raise any concerns.


Outlook / Prognosis

Is Frey’s syndrome serious?

While annoying, Frey’s syndrome isn’t harmful to your physical health. So, it’s not a serious condition in that sense. But excessive sweating that you can’t control can be uncomfortable and affect your mental health.

It’s important to seek help if the syndrome is causing you distress. Botox injections can help control sweating. It might be a good idea to see a therapist or psychologist, too, if it’s affecting your mental health.

Living With

When should I see my healthcare provider?

If your symptoms get worse or your treatment for Frey’s syndrome stops working, talk to your healthcare provider. They can suggest other options.

A note from Cleveland Clinic

Excessive sweating when you eat can be uncomfortable and bothersome. If Frey’s syndrome is affecting your quality of life, talk to your healthcare provider. They can recommend treatment options that can help manage gustatory sweating.

Medically Reviewed

Last reviewed by a Cleveland Clinic medical professional on 08/11/2023.

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