A woman treated a fungal infection with garlic and it gave her 2nd-degree burns

• A woman got second-degree burns on her foot after she used garlic to treat a fungal nail infection, according to BMJ Case Reports. 
• The report said the woman applied fresh raw garlic to her foot four hours a day for four weeks.
• Eventually the skin in contact with the garlic became swollen and blistered.
• Garlic can cause both chemical burns and allergic skin reactions, the doctors wrote in the report. 
• The story is proof of an important truth in skin care: Natural remedies aren't always better for your skin. 

A 45-year-old woman got burned — literally — by a natural remedy meant to cure toenail fungus.

A recent case study — first published in BMJ Case Reports on July 3 and reported by LiveScience on Friday — recounts the story of a woman who layered fresh garlic slices on her foot thinking it would cure a fungal nail infection. Instead, she ended up with a second-degree burn. 

The woman had been applying the fresh garlic to her foot four hours a day for four weeks, the doctors who authored the report wrote. The garlic eventually caused her skin to swell and blister. (You can see a photo of the burn on the BMJ Case Reports website. Warning: It's graphic.)

The authors wrote that, though raw garlic is believed to have antifungal and other medicinal properties, it can cause both chemical burns and allergic skin reactions. Some reported garlic burns are self-inflicted, but others have occurred in cooks and others workers who have to handle raw garlic, the report added.

Plastic surgeon Dr. Kai Wong, one author of report, told LiveScience garlic's natural sulfur-containing compounds appeared to cause the woman's painful symptoms. 

The woman's skin returned to normal and she was advised not to use garlic or other "topical herbal medicines" in the future, the report concluded. 

The woman's story is a good reminder that natural products aren't always harmless.

"People have to be really cognizant of the fact that just because [a product] is botanical, that doesn't mean it's not going to be an irritant or an allergen," Dr. Mona Gohara , associate clinical professor at the Yale University department of dermatology, previously told INSIDER. "There's kind of a false sense of security thinking, 'Oh, it's botanical, it's not going to hurt me. It might not be carcinogenic, but that doesn't mean it's not going to irritate the skin."

And garlic isn't the only example.

"Poison ivy is natural but it can also cause a bad skin rash," dermatologist Dr. Allison Arthur told INSIDER earlier this year. "Another natural product I see being used a lot is coconut oil . I don't recommend using it on the face because it can clog pores and make acne worse."

That doesn't mean everyone will have negative reactions to natural ingredients. But it's good to remember that they're not universally better for skin.

And when it comes to nail fungus in particular, your best bet is antifungal medication. Nail fungus that's caught early can be treatable with over-the-counter antifungal products, but some people will need prescription antifungal pills from a doctor, according to the American Academy of Dermatology (AAD). The Cleveland Clinic recommends seeing a dermatologist or podiatrist if you suspect you've got a nail fungus problem.

For more great stories, head to INSIDER's homepage.

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