There’s no shortage of products on the market that are claimed to thicken hair, remove wrinkles, and fix dry, brittle nails. Among these are a slew of dietary supplements, some topping $100.

But can a pill restore your hair, skin, and nails? Here's what the research shows:

What the Science Says

Hair, skin, and nail supplements commonly contain antioxidants such as vitamins A, C, and E, or Coenzyme Q10, as well as biotin, a B-­complex vitamin. The minerals manganese and selenium are often found in supplements marketed for healthy hair, along with fatty acids such as fish oil and flaxseed oil.

Deficiencies of these nutrients, ­although uncommon, may cause a litany of hair—and, sometimes, skin and nail—changes. Over time, for instance, insufficient intake of vitamins A and E can cause rough, scaly skin patches. A deficiency of biotin may cause eczema and hair loss.

But for those with no clear deficiencies, experts say there's no good evidence that supplements can make a difference.

“I’m not aware of any robust data suggesting that any supplements can treat natural, aging-related hair loss or nail damage, or give you healthier skin,” says Pieter Cohen, M.D., an assistant professor of medicine at Harvard Medical School and an expert on dietary supplements.

Two 1990s studies did find that biotin supplements may help strengthen soft, easily breakable nails. But the studies were small and not rigorously conducted, and haven’t been replicated, Cohen says.

“It’s nothing that would ever lead me to recommend it to any of my patients,” he adds. 

What If You're Deficient?

Most people get enough of the nutrients mentioned above through diet, but in rare cases, a medical problem may cause a deficiency or affect your hair, nails, or skin. People who take antibiotics long-term or use antiseizure drugs, for instance, are more likely to be biotin-deficient. An over- or underactive thyroid may cause hair loss and dry strands. Iron-deficiency anemia can lead to brittle, oddly shaped nails.

If you’re experiencing chronic hair, nail, and skin problems for no clear reason, talk with your doctor. “If nothing shows up after appropriate testing, because we don’t have a good blood test to detect biotin deficiency, it might be worthwhile to try a supplement for three months,” says Marvin M. Lipman, M.D., Consumer Reports’ chief medical adviser. “Since biotin supplements can interfere with thyroid testing, make your doctor aware.”

But remember that dietary supplements are not tightly regulated by the Food and Drug Administration and might contain substances not listed on the label or have much less or more of an ingredient than promised. For example, in 2008, one brand of multivitamin was found to have 200 times the labeled concentration of selenium—after it had caused hair loss and discolored, brittle nails in about 200 people across 10 states.

If you choose to take supplements, can you ensure that they are safe? Some carry one of four seals that might have some merit (U.S. Pharmacopeia, NSF International, ConsumerLab.com, and UL). Here, more about what these seals really mean.

Manage the Damage

Several lifestyle strategies can help you keep your hair, skin, and nails healthy. Try the following:

Eat enough protein. It’s important to maintain a healthy diet for overall health. But getting 30 percent of your daily calories from protein (preferably lean) can help keep your hair in shape.

Treat them well. Be cautious with hair dye (semipermanent is less damaging than permanent), blow dryers, flat irons, and styles such as tight ponytails. If you bite your nails, keep them trimmed or consider ­using a clear, bitter-tasting polish to help you stop. Wear cotton-lined gloves when washing dishes, moisturize hands and nails daily, and use moisturizing soap. Moisturize skin frequently and take short, tepid showers. Run a humidifier in your bedroom or office to keep the air between 30 and 50 percent humidity. If you smoke, work at quitting.

Protect yourself from the sun. Exposure to its UV rays can cause premature wrinkling, sagging, spots, and skin coarsening. Limit sun time and use a broad-­spectrum sunscreen of at least SPF 30 daily.

Consider Rx help. Prescription topicals such as tazarotene and tretinoin creams have been shown to reduce fine-line wrinkles, skin roughness, and sun and age spots. Over-the-counter formulations with retinol, retinaldehyde, retinyl ­esters, and oxoretinoids are also available, though less evidence supports their effectiveness. 

Editor's Note: This article also appeared in the June 2017 issue of Consumer Reports on Health.