There are at least two labels you should be mindful of if you're thinking about using essential oils — because if you're not, the consequences could be painful.

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These trendy products, which consist of a variety of plant extracts, are marketed as health supplements that provide a wide range of therapeutic benefits. The first label, required under federal law, notes that any health claims "have not been evaluated by the FDA" and that the products are "not intended to diagnose, treat, cure, or prevent disease."

But there's a second label on select essential oil products sold by doTERRA that some users only noticed when it was too late. That warning states that people who apply these oils to their skin should avoid "sunlight or UV rays for up to 12 hours." Failing to do so can result in chemical burns, as Elise Nguyen discovered earlier this week.

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Nguyen shared a series of photos on Facebook showing her skin, which blistered and burned when she used a tanning bed less than 12 hours after applying a doTERRA product to her wrists and neck. "I developed second and third degree burns from the oils," she wrote. "Currently, I'm on day 22 of this burn. I still have open areas and they still hurt if I hit them wrong."

Nguyen concedes it was her fault and said she doesn't blame the company, though she mentioned that the warning label is "teeny tiny." The point of sharing the photos was to raise awareness of this side effect for users who do not realize exposure to UV light could result in such serious skin damage.

She continued:

"[E]very yogi that I've talked to has no clue that this could have happened. So as summer is getting closer, and the weather is getting nicer, I just want everyone to be aware of this. Please, please read the bottles of anything you put on your skin. I wouldn't want this to happen to anyone else. It's been hell."

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In a blog post on doTERRA's website, Dr. David K. Hill, chairman of the company's scientific advisory board, explained that, "although unusual when the oil is used appropriately, risk for sensitivity increases when too much essential oil is applied, or when the oil is applied to young and sensitive skin."

"For some oils, like citrus oils, sunlight can be a trigger, so exposure to the sun should be avoided after topical application," Hill continued. "With other oils, it is not the sun but simply how your body interacts with the oil that causes the sensitivity. Awareness of your body and its responsiveness and limits is the best way to maximize efficacy and minimize sensitivity when using essential oils."

ATTN: reached out to doTERRA for a list of essential oil products that can produce a "phototoxic" response, but the company did not respond by the time of publication. We will update this story when we receive a response.