Why Do You Sweat When You Eat? Here's What Your Body's Trying to Tell You

You sweat in order to cool off your body. As sweat droplets evaporate, your skin cools down. So, if your upper lip develops sweat while eating a steaming bowl of soup or little beads run down your forehead after something super spicy, you can understand why you're perspiring. (By the way, this is an entirely normal body response, according to the Merck Manual.)

But there are also medical causes behind sweating after you eat, which is officially called "gustatory sweating."

While the location of sweating on your body doesn't really matter, there are other signs that might help you identify what's going on.

There are particular foods known for triggering the sweat response, which may include coffee, chocolate, spicy or sour foods, hot foods, alcohol and sweets, according to the International Hyperhidrosis Society.

"I don't often hear patients say that when they eat they sweat all over their body. When I do, patients have figured out that when they eat [a certain food], they sweat," says David Pariser, MD, a dermatologist and specialist in hyperhidrosis (excessive sweating) in Norfolk, Virginia.

If you notice a certain food does it (for example, carbohydrates can cause night sweats) — and you've been checked out for other medical conditions by your doctor — the simplest advice holds: Avoid that food to avoid the sweat.

This is a rare condition that happens after facial surgery around the parotid glands, which are salivary glands below your ears, according to the National Organization for Rare Disorders. This can happen as a result of surgery from a benign or malignant tumor in the parotid gland itself, a skin cancer removal or plastic surgery, Dr. Pariser says.

What happens, he explains, is that as skin and nerves heal following surgery, branches of the nerves that went to these salivary glands may essentially become mixed up and hook up to the sweat glands in skin. As saliva glands are stimulated in response to eating, which is part of the digestive process, they mistakenly trigger sweat glands to sweat.

"This is a dripping sweat. While it's not a serious medical condition, it can be disabling socially," Dr. Pariser says.

It's almost sure to happen if you had surgery on a parotid gland, though it's rare in cases of plastic surgery, he says. Most cases of Frey's involve just one side of the face.

As for treatment, "Botox injections are the most effective and easiest," Dr. Pariser says, adding that results usually last nine to 12 months, and up to two years.

While this is a first-line treatment for Frey's, there can be issues with insurance coverage (the treatment is off-label), though some companies will cover it. Regardless, while the upfront cost of Botox may be higher compared to medications, in the long run, it can be more cost-effective for patients, Dr. Pariser says.

People who have diabetic autonomic neuropathy — a complication of diabetes involving nerve damage — may sweat on the forehead, face, scalp and neck after chewing food, particularly after eating cheese, according to the American Diabetes Association.

"What I tell patients is that there's nothing the matter with their sweat glands, it's the switch that controls them," Dr. Pariser says. In this case, that switch is stuck on, and nerves are stimulating sweat when they otherwise shouldn't be.

This is a reactivation of the varicella-zoster virus, the one that causes chickenpox. It can cause a rather painful rash, and if this rash is on your face, then the nerves can be damaged, leading to gustatory sweating, per the Merck Manual.

This is known as secondary hyperhidrosis, according to the International Hyperhidrosis Society. You'll likely sweat on both sides of your face as well as your neck and chest. You might have this response when you eat or even just think about food, according to the organization.

Treatment for shingles includes antiviral medication, so see your doctor if this is happening to you.

This is a progressive brain disorder that causes shaking, makes walking difficult and affects balance, according to the National Institute on Aging. Both brain and nerve disorders are linked to sweating conditions.

If the cause of sweating after you eat is a side effect of a medical condition, you should be properly treated by your primary care provider or another specialist who can treat the underlying condition and provide specific suggestions for how to manage any sweating side effects.

Whether you are eating or not, craniofacial hyperhidrosis can cause excessive sweating of the head, face and scalp, according to the International Hyperhidrosis Society. This condition can indicate an underlying health issue, or it could be a side effect of a medication.

Treatments for excessive sweating on other body parts are helpful in managing craniofacial hyperhidrosis, too. This can include medicated antiperspirant, Botox or prescription medications called anticholinergics, per a November 2020 review in the ‌Journal Vascular Brasileiro‌.

Drinking alcohol can make you sweat because it increases your body temperature, per American Addiction Centers. This can be why you notice flushed skin or sweat droplets when having an adult beverage with dinner or dessert.

There are many reasons you could sweat when you eat — medications, underlying medical conditions, specific foods and more.

How can you differentiate between abnormal and normal sweating? Well, if it disrupts your daily routine, negatively affects your self-esteem or interrupts your meals or lifestyle, it's worth talking to a doctor about.

They may be able to run diagnostic tests to help you find the cause of your sweating and identify a treatment plan.

See a doctor immediately, however, if your excessive sweat is accompanied by lightheadedness, chest pain, shortness of breath, nausea or vomiting, per the Mayo Clinic, which could be signs of a heart attack.