The supply and demand for green beauty today is overwhelming—more than half of women want their skin care to be all-natural, according to a recent survey.

But as unaggressive as essential oils (a staple in these products) sound, they have become quite the modern skin aggressor.

"In my practice, I see at least two patients a week who are having reactions to essential oils," says Matthew Zirwas, M.D., director of the Ohio Contact Dermatitis Center.

According to a systematic review in The International Journal of Risk & Safety in Medicine, lavender, peppermint, tea tree, and ylang-ylang oils are the most likely to cause an allergic reaction (though one Polish study showed adverse reactions to 35 different oils!).

FOR SERENITY NOW: Skip the essentials.

Always do a patch test on your forearm before using something new.