The internet is hopeful, but what do the experts say?

In light of the COVID-19 outbreak, there has been some talk about mustard baths and whether they can help with the cold and flu-like symptoms that come with the disease.

Could the same kind of mustard you put on a burger potentially make a healthful addition to your bath? The short answer: maybe.

The long answer: While it packs some heat, this powdered seed doesn’t have the power to treat COVID-19, though it’s possible mustard baths may reduce the severity of some cold and flu symptoms.

The powder used for mustard baths comes from either yellow or black mustard seeds that are ground until fine. And yes, yellow mustard is the same seed used in the popular condiment.

A mustard bath is simply a mixture of mustard powder and Epsom salt or baking soda. While mustard as medicine has a long history, its use is becoming more and more popular.

Mustard baths have gained steam as a wellness trend in the last few years, touted as a home remedy for common ailments. There are plenty of online DIY recipes out there as well as some well-known brands that fans swear by.

But what does the science say?

There’s no evidence that mustard can treat COVID-19. Several medical doctors who were interviewed by Healthline had never even heard of mustard baths.

On the other hand, naturopathic physician Molly Force of Prosper Natural Health was familiar with mustard as a cold and flu treatment.

When asked whether she thinks that mustard could help with symptoms of COVID-19, Force was very clear: “With COVID, we don’t have any evidence, unfortunately, to support that it is going to be directly helpful.”

Kelsey Asplin, a naturopathic doctor in Denver, Colorado, and a professor in the integrative health care program at Metropolitan State University of Denver, agrees.

Regarding COVID-19, Asplin says, “Supporting one’s immune system so it can ‘fight the good fight’ is the best advice I could give any of my patients.”

If you think you have COVID-19, there are important things to know, like potential treatments, symptoms to look for, and when to seek care.

If your case is mild, there are specific recommendations for at-home treatment. Talk to your doctor before beginning any course of treatment to ensure that it’s right for you.

There are real risks associated with mustard baths as well.

The compound responsible for mustard’s therapeutic quality is called sinigrin. It’s also found in Brussels sprouts and broccoli, and is what gives mustard its spicy taste.

Sinigrin is thought to have antioxidant and anti-inflammatory effects, as well as have antibacterial, antifungal, and wound-healing properties.

The sinigrin breaks down in water to form allyl isothiocyanate. This volatile organic compound is what makes mustard spicy. It can also cause severe chemical burn on the skin and lungs.

A 2013 report describes a woman who developed contact dermatitis, involving redness and irritation, after applying a Chinese medicine patch containing mustard seed directly to her skin.

It’s clear that mustard is pungent in more than just taste.

Christopher D’Adamo, PhD, director of research and associate director of the Center for Integrative Medicine at University of Maryland, says that mustard should be used with caution.

“Mustard seed baths are not inherently dangerous at reasonable concentrations, but they certainly can be dangerous,” D’Adamo says. “Caution must be taken not to burn the skin at high concentrations. If the skin starts to flush uncomfortably, that would be a sign that too much was used, and that could be dangerous.”

Force echoes D’Adamo’s sentiments.

The treatment “would have to be very specific for the patient, which makes it a little bit tricky. Individualized assessment of the patient’s own constitution and how their illness is presenting is critical in the decision making,” Force says.

Force points out that it’s imperative to test the effect of mustard on a patient’s skin first by diluting a small amount in water and doing a patch test.

“Mustard can be very caustic to the skin and can burn some people. I usually recommend a small trial patch about the size of a quarter on their skin,” Force says.

Asplin feels similarly, noting that if left on the skin for too long, mustard can cause irritation and burns.

And if you have sensitive skin in general, it’s best to avoid it.

While there are risks, mustard baths do have some benefits, too.

When asked about the health benefits of mustard, D’Adamo says, “Mustard seed contains both glucosinolates and myrosinase enzyme that together produce isothiocyanates. These isothiocyanates help the body’s natural detoxification processes, reduce inflammation, and can offer protection against the development and growth of cancer cells.”

He also notes that easing cold symptoms like congestion is one of mustard’s “classic uses” and that mustard baths “may increase comfort levels” for cold and flu.

Force agrees.

“This is a traditional form of what I would consider hydrotherapy that helps with circulation and can basically induce a fever. It can stimulate heat in the body, so the theory is that by hoping to induce a low-grade fever, we can stimulate immune response and lymphatic movement,” Force says.

Force describes using mustard compresses with patients to help relieve chest congestion. Mustard has also been traditionally used in foot soaks.

In fact, recent interest in mustard seed baths may be linked to a small 2017 study. Researchers surveyed 139 people with respiratory tract infections to see whether mustard footbaths improved perception of their symptoms.

Participants who took the footbaths for seven minutes once a day for six days reported an improvement in four of five categories used to measure symptoms.

According to the study, “Footbaths as a complementary treatment option have a positive impact on the immune function and on the patients’ health due to its thermographic effect. It was also found that footbaths can lead to a reduction in stress.”

Force goes on to explain that mustard baths may reduce the duration of symptoms for colds and flus.

“Because it’s a heating therapeutic, it helps open up the pores and stimulates sweat and the opening up of the sweat glands, so it’s considered to be helpful for movement [of] toxicants out of the body,” she says.

According to Asplin, mustard baths can be useful for breaking up congestion in the lungs and sinuses.

“Mustard baths are also very useful for dealing with body aches and pains, as well as relaxing and de-stressing,” she adds.

Mustard has been used medicinally as far back as ancient Greece and India, and still has a prominent place in Ayurvedic medicine.

According to Ayurveda, mustard has a heating quality when ingested or applied topically, which explains why it’s touted as a detox method. If you heat up the body to the point of sweating, the logic goes, you release toxins.

There’s some evidence early Western medicine used mustard for its medicinal properties. An 1845 publication of The Lancet medical journal mentions the use of mustard baths and mustard poultices to reduce inflammation.

And an 1840 publication of the same journal mentions the use of a mustard bath to induce sweating, and that at low doses a mustard bath “causes a sensation of warmth which not only is pleasant and soothing to the patient’s feelings, but provides the body with optimum conditions demanded for combating the invading organisms.”

The article also warns that mustard can cause burns, producing a tingling that becomes “unbearable.”

Interestingly, a 2012 study indicated that mustard can reduce the symptoms of contact dermatitis. However, that study was conducted on mice, and it’s unclear if the results can be generalized to humans.

There’s plenty of data that shows mustard seeds and leaves are chock-full of nutrients. Of course, you’d have to eat them if you want to get those nutrient benefits, not bathe in them.

Mustard is also rich in antioxidants. Mustard boasts flavonoids that may protect against type 2 diabetes, heart disease, and possibly some cancers.

These antioxidants might protect against bacteria like E. coli, B. subtilis, and S. aureus., but study results are mixed. Plus, there’s no evidence that these antioxidants can be absorbed through a bath.

Mustard baths aren’t an effective treatment against COVID-19. They may be beneficial for colds, flus, aches, and pains, as well as general stress relief.

Always talk to your doctor before trying a mustard bath.

When it comes to COVID-19, you can stay in the know by educating yourself according to doctor recommendations.

Crystal Hoshaw is a mother, writer, and longtime yoga practitioner. She has taught in private studios, gyms, and in one-on-one settings in Los Angeles, Thailand, and the San Francisco Bay Area. She shares mindful strategies for anxiety through group courses. You can find her on Instagram.