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Frey syndrome: sweating while eating after parotid surgery | CION Cancer Clinics
Frey syndrome is sweating and flushing of the cheek in front of the ear whenever you eat. It is a known after-effect of parotid surgery, caused by healing nerve fibres growing into the skin. It is not a sign the tumour is back. It can be treated, from a simple antiperspirant to small injections that stop the sweating for months. This page explains what to expect and what to ask. CION Cancer Clinics’ surgical oncologists in Hyderabad can talk this through with you.
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Medically reviewed by Dr. Muralidhar MuddusettyConsultant Surgical Oncologist · MBBS (AIIMS), MS (Surgery, AIIMS), DNB (Surgical Oncology), MRCS (Edinburgh) · last reviewed September 2026, next review due September 2027
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On this page
- What is Frey syndrome, and can it be treated?
- When does it start, and how is it confirmed?
- How is Frey syndrome treated?
- Is this Frey syndrome, or something else?
- Four things families tell us, and what is actually true
- Words you will see, in plain language
- What this page cannot tell you
- Common questions about Frey syndrome
The short answer
What is Frey syndrome, and can it be treated?
Frey syndrome is sweating and flushing of the cheek in front of the ear whenever you eat, and it is a known after-effect of parotid surgery. It can be treated. Most people need nothing more than an antiperspirant cream; those who are troubled by it can have small injections into the skin that switch the sweating off for months at a time.
Why it happens
The parotid gland makes saliva, and tiny nerve fibres tell it to do so when you eat. When the gland is removed, those fibres are cut. As they regrow over the following months, some of them find their way into the sweat glands and small blood vessels of the skin that now lies directly over the operation site. From then on, the signal that used to mean "make saliva" reaches the skin instead, so the skin sweats and goes red.
What it is not
It is not a sign that the tumour has come back, and it is not a sign that anything went wrong in the operation. It is a wiring mix-up in healing nerves, and it happens to some degree in many people who have had this operation, whether the tumour was harmless or a cancer. It does not spread, and it does not harm the skin. Spicy, sour and very hot food bring it on most strongly.
If sweating starts on the cheek without eating, or comes with a new lump, pain or facial weakness, that is a different problem and needs a review.The sequence
When does it start, and how is it confirmed?
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The first months after surgery
Nothing. The cut nerve fibres have not yet regrown, so there is no sweating at all, which is why it surprises people later.
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The first signs
Usually a warm or prickling feeling in front of the ear while eating, then a visible flush, then dampness. Some people only ever get the warmth and never the sweat. It can appear many months after the operation, sometimes well over a year later.
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The starch-iodine test
Usually the story alone is enough for the diagnosis, and your surgeon feels the area to be sure there is no lump underneath. Before injections, iodine is painted on the cheek and dusted with starch. You suck something sour, and wherever sweat appears the powder turns dark.
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Choosing a treatment, or none
You decide together how much it bothers you. Mild dampness that only you notice may need no treatment. Sweat that drips at family meals is worth treating, and the options are set out below.
Not sure whether this applies to you?
Ask an oncologistThe options
How is Frey syndrome treated?
From simplest to most involved. Your surgeon will usually start at the top of this list and move down only if needed.
Antiperspirant on the cheek
A strong aluminium chloride antiperspirant, the kind sold for sweaty palms, applied to the dry patch at night. Cheap, safe and often enough for mild cases.
Does not suit
- Skin that is still healing or irritated
- Anyone whose sweating is heavy
A prescription cream
A cream containing glycopyrrolate, a medicine that blocks the nerve signal to the sweat glands, applied before meals. It is prescribed and made up specially, and the eyes must be avoided.
Not for people with glaucoma or urinary retention without a doctor's say-so, because the drug can worsen both.Botulinum toxin injections
Many small injections into the mapped patch of skin, done in the clinic. The sweating stops within days and stays away for months, then the injections are repeated. This is the usual treatment for troublesome cases.
Does not suit
- Pregnancy and breastfeeding
- Certain muscle-weakness conditions
A barrier under the skin
A layer of the person's own tissue or a manufactured sheet placed between the nerve endings and the skin. It is mostly done at the original operation as prevention. As a later fix it means another operation, so it is rarely chosen.
Side by side
Is this Frey syndrome, or something else?
Frey syndrome
Needs a review instead
Sweating and redness only while eating or thinking about food
Sweating at rest, at night, or across the whole face
Confined to the patch of skin over the operation
A new lump, swelling or pain under that skin
Appears months after the operation and stays much the same
Fever, discharge from the wound, or fluid leaking when you eat
The face moves normally
New weakness of the face, or an eye that no longer closes
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Commonly believed
Four things families tell us, and what is actually true
"The cheek sweats when she eats, so the tumour must be back."
Sweating with meals is a nerve wiring effect, not a tumour effect. A tumour coming back shows itself as a lump, pain or weakness, not as sweat. Raise it at follow-up, where the area is examined anyway.
"It means the surgeon damaged something."
The nerve fibres that cause it have to be cut to remove the gland. What happens afterwards is the body's own healing finding the wrong target. Surgeons can lower the chance with a barrier layer, but cannot remove it entirely.
"Botulinum toxin is only for wrinkles, and it is dangerous."
The same medicine is used at low strength in the skin for excessive sweating of many kinds, and has been for years. Injected into the cheek skin it does not reach the facial muscles at the amounts used, so it does not weaken the smile.
"It will keep getting worse until it takes over the face."
It reaches its full extent once the nerves have finished regrowing and then stays much the same. It does not spread beyond the operated skin. Many people find it slowly becomes less noticeable.
On your notes
Words you will see, in plain language
- Gustatory sweating
- The medical name for sweating brought on by eating. It is the same thing as Frey syndrome.
- Auriculotemporal nerve
- The nerve that carries the "make saliva" signal to the parotid, and also carries feeling from the skin in front of the ear. Its cut fibres are the ones that regrow into the skin.
- Minor's starch-iodine test
- The painted-on test that turns dark wherever the skin sweats. It is used to confirm the diagnosis and to map where injections should go.
- Interposition barrier
- A layer placed under the skin at surgery to block regrowing nerve fibres. Also written as a fat graft, SMAS flap or dermal matrix.
Being straight with you
What this page cannot tell you
It cannot tell you whether you will get Frey syndrome, or how badly. That depends on how much gland was removed, how the skin flap was raised, and whether a barrier layer was placed, all of which are questions for your surgeon rather than for a web page.
It cannot promise how long an injection will last
The sweating stays away for months in most people, but the exact time varies from person to person and from one round to the next. Your surgeon will tell you what they have seen and book a review rather than a fixed repeat date.
It cannot tell you what treatment will cost
Creams and antiperspirants are inexpensive. Injections are priced by the amount used and have to be repeated, so ask your centre for a written estimate and whether Aarogyasri, CGHS, ECHS, EHS or your cashless insurer covers it as part of cancer follow-up.
If you are not sure whether what you are seeing is Frey syndrome, call the helpline and describe it. We will help you reach the right person rather than leaving you to guess.Questions we are asked
Common questions about Frey syndrome
Does Frey syndrome go away on its own?
Sometimes it fades, and often it simply becomes less noticeable as you learn which foods set it off. It rarely disappears completely once established, because the nerve fibres have already regrown into the skin. That is why treatment is offered for anyone who finds it troubling rather than waiting it out.
How long after the operation can it appear?
Not in the first weeks, because the nerves have not regrown yet. Most people who develop it notice it some months after surgery, and it can appear well over a year later. A new symptom that late often worries families, which is why it helps to know in advance.
Will the injections weaken my face?
They are placed just under the skin, not into the muscle, and the amount used is small. Weakness of the smile is rare, and if it happens it wears off. Tell the doctor if you already have any facial weakness from the operation, because that changes how they place them.
Is it linked to the tumour being a cancer?
No. It follows the operation, not the type of tumour, and it happens after removal of harmless tumours in the same way. What can make it more likely is a larger operation or radiotherapy to the same area afterwards, because both affect the skin over the gland.
Can I do anything about it myself?
Yes. Notice which foods trigger it, usually sour, spicy and very hot dishes, and expect it with those. A strong antiperspirant applied to the dry patch at night helps many people. Keep a tissue at meals. Do not put anything on the skin that stings or that you have not asked about.
Can it be prevented at the time of surgery?
Surgeons can place a layer of tissue or a manufactured sheet between the nerve endings and the skin, which lowers the chance without removing it entirely. It is not done in every case. If you have not had your operation yet, ask your surgeon whether they use a barrier and what they recommend for you.
Is the starch-iodine test uncomfortable?
No. The iodine and powder are painted and dusted on, you suck a sour sweet or a piece of lemon, and the patch is photographed. The stain washes off. Say beforehand if you are allergic to iodine, because a different method can be used.
Who should I see about it, the surgeon or a skin doctor?
Start with the surgeon who did the operation, or the surgical oncology team following you up, because they need to examine the area anyway. They may then refer you to a dermatologist for the injections. Between follow-ups, call the helpline and we will arrange the review.
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Sources
- American Cancer Society — Surgery for salivary gland cancer
- Cancer Research UK — Surgery for salivary gland cancer
- NHS — Excessive sweating (hyperhidrosis)
- Macmillan Cancer Support — Salivary gland cancer
This page is general information, not a prescription. Do not change or stop any treatment based on what you read here. If anything is worrying you, contact your own treating team — or call our helpline and we will help you reach the right specialist.
Keep reading
Related pages
Parotidectomy: what the operation involvesWhy the nerve fibres have to be cut in the first placeSuperficial vs total parotidectomyHow the size of the operation changes what followsHollowing of the cheek after parotidectomyThe other late change families ask aboutRecovery after parotidectomyThe full timeline after the operationComplications and red flagsWhat does need a same-day call
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