Hair loss in women is rarely talked about, but it's much more common than you might imagine. In fact, as many as 40 percent of women have visible hair loss by the time they reach 40, estimates the American Academy of Dermatology.

Thinning hair and hair loss in women can be chalked up to a wide variety of causes. Physical and emotional stress, poor nutrition and genetics (often the source of female pattern hair loss and post-menopausal hair loss) can all cause hair loss. To be sure, there's a difference between wanting to add some volume and 'oomph' into your hairstyle and truly needing products for thinning hair or hair loss. If you've recently gone through a hormonal change, like switching up your birth control brand or having a baby a baby, your hair loss is most likely temporary. But if you notice your hair thinning progressively over time, or you see noticeable loss around the crown and hairline, you may need to look into hair loss treatments.

We researched the newest products for thinning hair (along with a few tried and true favorites) with the help of cosmetic chemists, dermatologists and specialists in thinning hair to tell you which ingredients and formulas will get the job done. Here, your new secret weapons in combatting hair loss.

Image via Getty

"If hair is just beginning to thin, Keranique Hair Regrowth Treatment Spray, $30, is a great first product to try," says fine hair specialist Lucinda Ellery. The product contains 2 percent minoxidil (that's the wonder ingredient in Rogaine), which not only helps stop hair loss, but also promotes regrowth with constant use. But Ellery does warn you need a little patience. Minoxidil-based treatments can take up to three months of use to see results. Plus, the spray is a leave-in treatment, which Dr. Jeannette Graf, M.D., assistant clinical professor of dermatology at The Mount Sinai Medical Center, says could prove a more effective method because it has greater contact time with the area it's treating than other thinning hair products. Sold and sold.

A specially formulated cleansing system can help your mane stay strong and appear fuller. "Shampoos and conditioners work on the appearance of the hair itself and the outer cuticle," says Dr. Graf.

Hairstylist Jon Reyman of Spoke & Weal, a salon with locations including New York and Los Angeles, recommends Aveda Invati Exfoliating Shampoo,$30, and Thickening Conditioner, $30, to prevent sebum buildup on the scalp. "I'm a big proponent of natural solutions," he says, "and I've seen this make a difference on clients."

Looking for a drugstore option? Consider Avalon Organics Biotin B-Complex Shampoo and Conditioner, $9.95 apiece, which build body in fine strands. Or, to protect color-treated hair, try ColorProof BioRepair-8 Anti-Thinning Shampoo and Conditioner, $44 apiece, both of which block DHT, the hormone that damages hair follicles.

A new import to the United States, Danish hair-loss clinic Harklinikken claims success in improving hair growth among 95 percent of its 70,000 users. The hero treatment is the topical Extract, $88, made with ingredients derived from cow's milk and plants. Each formula is customized for the client based on age, gender, family history and hair loss. Applying nightly is key, and the program includes weekly online check-ins with a Harklinikken representative to track progress. Note that it won't work for certain conditions such as scarring or alopecia, but otherwise, expect to see fuller hair beginning in a few months.

If you seek immediately visible results, try hair-building keratin microfibers such as Focus Hair Building Fibers, $24.95, and Toppik Hair Building Fibers, $24.95. WAnd while the secret behind what makes these fibers work is all very scientific (the fibers basically act as a magnet and bond with your hair), we think Toppik's ingenious ad campaigns really show the results best. "These aren't permanent solutions to hair loss," says Ellery, "but rather a short-term camouflaging technique that resists sweat, rain and daily wear, and wash out easily with shampoo." If your scalp is starting to show bare patches, these fibers (which come in eight or nine different shades) are a quick solution with no telltale signs of anything unnatural.