You've seen the blog posts and the news stories and the all-caps updates on your friends' Facebook walls: "There are cancer-causing chemicals in your hair salon!" "Your acne product could send you to the ER!" But in our share-now, think-later culture, it's sometimes hard to figure out what's truly a cause for concern. So we played detective, poring over the relevant research and surveying top-of-their-field experts to dig up the helpful, often calming truth. Now, that's something we can all "like."
The Hype: "Your acne medication could send you to the hospital"
The Whole Truth: In June the FDA issued a warning about allergic reactions to two widely used OTC acne-fighting ingredients—salicylic acid and benzoyl peroxide. It's important to look at the actual numbers here. This warning was based on 131 reported reactions over the span of 44 years—that's a pretty rare allergy. Plus, not a single one was fatal.
"About 10% of people using benzoyl peroxide will have an issue, and the vast majority of those will amount to nothing more than redness and flakiness of the skin," says Elizabeth Tanzi, M.D., assistant professor of dermatology at George Washington Medical Center in Washington, D.C. Reactions to salicylic acid are even more rare. Anyone who's allergic to aspirin, however, should avoid salicylic acid because it's derived from the drug. If popping an aspirin sparks asthma-like symptoms, using an acne cream with this ingredient could have the same effect.
For anyone else, doing a patch test (dabbing product somewhere inconspicuous, like your inner arm) for three days before slathering on a new cream will alert you to any potential reactions, says Julie Karen, M.D., clinical assistant professor of dermatology at New York University Langone Medical Center.
The Hype: "Is drugstore sunscreen safe?"
The Whole Truth: Some research has found that oxybenzone, a chemical sunscreen in many popular brands, may mimic estrogen and testosterone in the body, possibly increasing your risk of breast cancer. Note the use of "may" and "possibly" here? That about sums it up. These tests were conducted on mice, not humans, using very high levels of the ingredient—hardly a smoking gun. "Oxybenzone has never been shown to cause cancer in people," says Rachel Reynolds, M.D., assistant professor of dermatology at Harvard Medical School. The alternative is to use physical blockers like zinc oxide and titanium dioxide. Instead of being absorbed, these ingredients sit on your skin to deflect the sun's rays. The only potential drawback is that they may leave a whitish cast on your face, but these two are nearly invisible: Neutrogena Pure & Free Liquid Daily Sunscreen SPF 50 ($13, drugstore.com) and MD Solar Sciences Mineral Crème for Face ($30, Sephora).
The Hype: "Gel manicures can harm your skin!"
The Whole Truth: A recent study in JAMA Dermatology found that the lamps used to harden gel nail polish emitted varying levels of UV light and that some could pose a small cancer risk with multiple manicures. But this study measured only the UV light emitted from the lamp, not how much was absorbed by people, says Dana Stern, M.D., assistant clinical professor of dermatology at NYC's Mount Sinai Medical Center. She says that dermatologists use UV light to help psoriasis and eczema patients, and that it would take 13,000 sessions under a nail lamp to reach the same exposure you'd get from one treatment in a doc's office.
This being said, any amount of UV light can up the odds that you'll get wrinkles and dark spots, so slap some waterproof sunscreen on your hands before your next gel manicure. Or opt for one of the new gel-like polishes that offer long-lasting color and shine without the lights, such as Sally Hansen Miracle Gel ($20 for a polish and a top coat, at drugstores).
The Hype: "Does that skin-lightening ingredient cause cancer?"
The Whole Truth:Though hydroquinone, used for years to fade dark spots, has been banned in some countries, "there have been no human studies that show a link between this ingredient and any form of cancer," says Rachel Reynolds. The two studies that have shown a link to kidney cancer involved mice with predisposing end-stage kidney disease—and they were fed the ingredient. Lots of it. The amount would be comparable to a 132-pound woman applying multiple tubes of a prescription cream daily.
For this reason, many doctors still consider hydroquinone the gold standard in dark-spot removal. But keep in mind that you're meant to use only a tiny amount for a limited time (two to three months, tops). If the mouse-study results still give you the willies, there are other options: Kojic acid, niacinimide, vitamin C, and retinol are all great lighteners, says Julie Karen. She likes SkinMedica Lytera Skin Brightening Complex ($125, skinmedica.com).
The Hype: "Keratin straightening treatments are dangerous!"
The Whole Truth: This one is worth worrying about. After the FDA and the U.S. Department of Labor's Occupational Safety & Health Administration warned about the unsafe levels of formaldehyde in these treatments, a flood of supposedly formaldehyde-free formulas hit the market. Many of the newer options are free of this known carcinogen, but some have other chemicals that turn into formaldehyde when mixed and heated. The results of exposure range from annoying (it can irritate the lungs, nasal passages, and eyes) to truly dangerous.
Most at risk are hairstylists, who breathe in the chemical daily. "A few treatments over your lifetime are probably no big deal," says Nicole Rogers, M.D., assistant clinical professor of dermatology at Tulane University in New Orleans. Still, it's wise to seek out a truly clean alternative—for your sake and the salon workers'. Two new brands, Anevolve and Cezanne Finish, rely on amino acid–based compounds to smooth hair, says cosmetic chemist Jim Hammer. "Both are free of formal dehyde and any chemicals that could become formaldehyde," he says.
The Hype: "Hair color can make your face blow up like a balloon!"
The Whole Truth: NCIS star Pauley Perrette—known for her Bettie Page–esque black hair—recently warned fans about a common ingredient found in dark hair dye called p-phenylenediamine (PPD) that sent her to the ER with severe swelling. Allergic reactions to PPD are a real thing. As with Perrette, who's been coloring her hair for years without a problem, they can develop over time, says Bruce A. Brod, M.D., clinical professor of dermatology at the University of Pennsylvania Perelman School of Medicine.
These side effects are relatively uncommon, but people with dandruff and psoriasis of the scalp may be at a higher risk. The bottom line: Everyone should do a patch test before using a new dye. If the test doesn't cause problems but you later notice a rash, hives around your ears and the nape of your neck, or sudden itchiness of your scalp after coloring, see a dermatologist immediately.
This story originally appeared in the December 2014 issue of Dr. Oz The Good Life.