FOREVER YOUNG

Dermatologists reveal the sneaky causes of hair loss — and the simple strategies for speedy regrowth

Lately it seems like every day is a bad hair day, with our locks looking thin, flat and dull. Partly to blame? The cold weather, which dries out the scalp, making hair prone to shedding. But that’s not the only wintertime culprit. “Some common habits can actually trigger fallout,” says dermatologist Francesca Fusco, M.D., who treats celebrities in her New York City office. Here, three easy strategies that can help you get thick, lustrous locks in no time.

WASH HAIR WITH THIS

The hats we wear to stay warm during the winter come with a surprising downside: "The heat that hats trap in on the scalp can spur yeast growth and cause inflammation,” says dermatologist Carl Thornfeldt, M.D., founder of Epionce skin care. This causes thinning of follicles, resulting in hair loss. The fix? Switch to a shampoo containing piroctone olamine (we like The Body Shop Ginger Scalp Care Shampoo, $14, thebodyshop.com). Studies show the compound decreases scalp fungus by 82 percent and reduces hair loss by 17 percent within six weeks.

SWAP YOUR HAND SOAP

We rely on germ-fighting cleansers to ward off colds, but our hair could pay a price. The reason: Some antibacterial products contain chemicals that experts say may interfere with the endocrine system and hinder the body’s production of thyroid hormones. When theses hormone levels are imbalanced, the hair growth cycle slows. To fight germs without side effects, switch to a soap that's free of endocrine disruptors (we like Mrs. Meyers Lavender Hand Soap, $4, target.com). The FDA reports they’re just as effective as their antibacterial counterparts. Once chemicals aren’t impeding hormonal balance, the hairgrowth cycle can return to normal.

TRY A DIY “DRY” SHAMPOO

The powdery sprays nix greasy roots and add volume to fine strands — but overuse (more than three times between washes) can clog hair follicles. This causes scalp irritation which results in more shedding, Dr. Fusco warns. A better alternative: a witch hazel spritz. The astringent breaks down dirt and oil buildup on the scalp without leaving any follicleclogging residue behind. To do: Mix

cup of water with cup of witch hazel and 3 drops of peppermint oil

(it stimulates blood flow to encourage hair growth) in a spray bottle. Shake and spritz lightly onto roots, then rub into the scalp for 30 seconds (this also increases circulation); let dry. Use up to three times a week.

“[Great hair] is really just about doing less and using good products.”

Jennifer Aniston, 48