Seeking longer and thicker lengths? The best hair growth serum can do more than boost your confidence—it can help create the right conditions for stronger, healthier strands, especially as your hair changes with age, stress, or hormonal shifts. While no serum can turn back time, the right formula can support growth, minimize shedding, and improve the appearance of thinning hair.

Still, not all serums are created equal. Understanding the cause of your hair changes is essential before investing in a product. “I encourage everyone concerned for hair thinning or shedding to consult with a health-care provider first,” says Dr. Paradi Mirmirani, MD, a board-certified dermatologist specializing in hair disorders at Kaiser Permanente in Vallejo, CA. “The best guidance is to ask questions and rely on trusted sources for scientific evidence and advice tailored to your needs.”

Vogue’s Favorite Hair Growth Serums

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That’s because everything from genetics and hormones to nutrition, medications, and emotional stress can contribute to hair thinning, and those underlying causes influence which ingredients will be most effective. It’s also important to know whether your goal is fuller hair or longer lengths, as the two aren’t always addressed the same way.

“Some serums for hair density versus length are essentially the same, and they often have overlaps in formulation,” cosmetic dermatologist Dr. Blair Murphy-Rose tells Vogue. “Generally speaking, however, hair growth serums for increasing length are formulated to strengthen strands, prevent breakage, and support the growth phase of the hair cycle. These help to promote healthier, longer strands. Serums that treat hair thinning focus on follicle health, reactivation of dormant hair follicles, and reducing shedding. They often address inflammation and/or hormonal factors. They may increase nutrient delivery to the hair and enhance circulation,” Dr. Murphy-Rose says.