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Having thick, healthy hair is a dream for many, but hair thinning and loss is more often the reality, especially as we get older. While men are more likely to lose hair than women, anyone can deal with shedding and patchy spots, and the factors behind this aggravating change are wide-ranging.

"Typically, whenever you see a condition, there's never going to be one root cause or one underlying cause," explains trichologist Bridgette Hill. "The hair loss I see in practice is primarily genetic, hormonal, and related to deficiency issues." Essentially, she explains, hair is a "nonessential tissue," so when your body is going through any kind of change—positive or negative—it can trigger hair loss as it works to return to homeostasis.

There are more negative triggers, too. "Aside from genetic hair loss, telogen effluvium (or temporary hair loss) is a common cause of shedding and can result from thyroid conditions, stress, hormonal imbalances, pregnancy, anemia, and crash dieting, among others," says dermatologist Christine Shaver of Bernstein Medical Center for Hair Restoration in New York City. "Some of this hair loss can be reversed by correcting the underlying cause."

Dealing with these kinds of issues can lead you to look for solutions—one of which can be a hair growth serum. These products are formulated with ingredients that help to stimulate hair growth and extend the growing period of each strand of hair, which means less shedding. Along with other tactics, like consulting with a professional to address why you might be experiencing hair loss, serums can be a component of a scalp care routine that results in thicker, longer hair.

These are the best hair growth serums to try, according to experts:

"You want to look for things with zinc, selenium, horsetail oil, vitamin D, and vitamin B," says Hill. She also notes that biotin—a buzzy ingredient in the world of hair care lately—may be present, but it's unlikely to have any real results on your hair growth, unless you're biotin-deficient (which she says is also unlikely). Dermatologists like Paul Jarrod Frank, MD and Shaver recommend the FDA-approved topical minoxidil, which you may know by its brand name, Rogaine, as a clinically proven combattant to hair loss.

It's important to note, however, that hair growth serums aren't a miracle, and if you're actively struggling with hair loss, it's best to see an expert who can determine the (sometimes literal) root cause before you start trying new products. "Every situation requires a different type of treatment," says trichologist Nicole Jones. "Hair grows about half an inch to 1 inch a month in most cases. Growth can be encouraged by our practices, but patience is necessary on this journey." She recommends seeing a dermatologist or trichologist to get a proper diagnosis for your hair loss and starting a scalp care routine, giving yourself regular scalp massages and cleansing it well.

Hill echoes this sentiment: "If someone's really committed and says, 'I just want to have the best hair for the rest of my life for as long as I can and I'm committed to putting the work in,' absolutely, you're going to get a benefit from that."

Along with a proper diagnosis for hair loss, a diet full of healthy, whole foods, and good scalp care, hair growth serums can be a component of a routine that results in your best hair yet.

If you're actively struggling with hair loss, you'll want to reach for this over-the-counter option, as Shaver says minoxidil—which comes in both 2% and 5% options—is the best choice for combatting genetic hair loss. "It should be used continually and should not be stopped and restarted. Shedding may occur during the first few months and is usually an indication that the medication is beginning to work," she adds. "Results can take up to one year and the product should be continued for ongoing results."

Over 4,500 Amazon shoppers have given this particular treatment from Rogaine a five-star rating. "For me, this product is like a miracle," one wrote. "Four months after starting with this product, I feel like a new person. I can wash my hair and collect a normal amount of shed hair in the drain. When I brush my hair, a few come out, again, that's normal."

This oil treatment by EssyNaturals is Amazon's best-selling hair regrowth treatment for a reason. It's available at a budget-friendly price of $22 and includes ingredients like castor oil and caffeine that nourish hair at the root and encourage growth. Some shoppers even say it helps relieve their itchy scalps.

"I was noticing thinning along my hairline and very frizzy ends. I almost tried minoxidil but decided to give a natural remedy a shot first," wrote one reviewer. "I can notice a difference after 2 weeks! So many little baby sprouts, and my hair texture has completely changed. It feels so much softer and thicker. So happy I took a chance on this oil."

Pura D'Or's scalp serum gets a stamp of approval from over 3,300 Amazon shoppers. To encourage hair growth, it contains DHT blockers to reduce hair fall, as well as caffeine to help stimulate the scalp.

"I have thinning hair and a bald spot on my scalp which was very obvious, as the result of dealing with a chronic illness… I have been using this product for almost a month now (along with a thyroid supplement) and it is definitely helping," wrote one shopper. "Within 2 weeks the hair on my scalp started coming in thicker and I no longer look like I am going bald! I love that this product is made with natural ingredients, no harsh chemicals, and the smell is nice and not overwhelming."

This best-selling serum from Vegamour is made with powerful plant-based ingredients, including mung bean—which is rich in zinc, selenium, iron, and many more vitamins that are important for hair health. Clinical trials conducted by the brand showed that after four months of use, the serum increased the appearance of hair density by up to 52% and decreased shedding by up to 76%.

"I've used many products for my thinning locks due to chemo.This is the first product I've used that there was any noticeable difference," wrote one reviewer on Vegamour's site. "I also love that the smell is so clean and not too perfumey."

Saw palmetto, one of Hill's favorite hair growth ingredients, works by blocking the formation of DHT—a molecule that contributes to hair loss. In this serum, it's paired with other plant-based ingredients like pumpkin seed oil, moringa oil, and flaxseed oil to help hydrate and nourish the scalp and reduce thinning.

While many reviewers say it takes patience to see significant results, others are surprised at how quickly their hair thickness changes. "I started losing hair due to stress. I found this product and have been using it for around a month. I can honestly say that after a week I noticed less and less hair fall out," wrote one. "I use this product every night. I massage the oil all over my scalp and wash in the morning. I've noticed new hair growth as well as thickening of existing hair."

If you don't love the idea of leaving a product on your hair for hours, this Ayurvedic-inspired hair oil can be applied as little as five minutes before you shower (but left on overnight if you want even better results). One of its key ingredients is ashwagandha, which Hill recommends for supporting circulation of the scalp.

"I've experienced significant hair fallout over the last year and have been looking for anything and everything to help," wrote one reviewer. "I've been using this regularly for about 2 months now. My hair is definitely shinier and healthier. My hair texture looks more wavy and less frizzy if I let it air dry. My hairdresser said she thought it looked thicker as well."

"Hair growth serums work by increasing blood flow to the scalp with proteins and antioxidants," explains Madfes, who includes this serum by GrandeHair in her recommendations. It's formulated with procapil, ginkgo biloba, and botanical extracts to stimulate growth. A 16-week clinical trial conducted by the brand found that 97% of participants saw an improvement in their hair thickness and a reduction in thinning.

"After a cancer diagnosis and chemotherapy treatment, when I thought that I was never going to feel like me again, I found this product and started using it 3 months ago," one shopper wrote. "The results: my hair grew back super fast and looks fuller and feels softer than ever. Absolutely love it!"

A lot of hair growth serums require daily use to really see results, especially if you're dealing with hair loss. But this serum, which Hill recommends, is applied to the scalp just once a week—and there's no rinsing necessary. It's made with natural ingredients like lemon essential oil and a lotus mineral extract. A clinical study conducted by the brand showed that a majority of participants saw results in as little as 30 days.

"I actually now have slightly thicker hair than I ever had," wrote a shopper who started using the serum after sudden hair loss due to a medical condition. "This product very much helped with the overall regrowth. Highly recommend."

Don't feel like rinsing out a heavy oil or serum? This leave-in foam is developed by dermatologists Steven Shapiro, MD and Michael Borenstein, MD and contains ingredients like saw palmetto and a caffeine derivative. It's applied to the scalp either in the morning or night, and shoppers say it doesn't make hair feel oily.

"I followed the once a day application instructions and I noticed within the first week the amount of hair shedding decreased," wrote one reviewer. "The texture of my hair feels stronger and smoother. The shedding continues to decrease. For the first time in 10 years of trying I can see and feel positive results on my hair and I am excited to see my hair grow."

Another favorite of Hill's, this concentrated serum strengthens hair at the root while cleansing the scalp with the help of orange peel oil and castor seed oil. It's recommended for use once or twice a week and applied by massaging into the scalp before shampooing it out.

"I've been using it for almost two years now. Initially used it twice a week and now I use it twice a month for maintenance," wrote one shopper. "My hairdresser can't believe how much thicker and fuller my hair is. It absolutely does help to regenerate new hair growth. I would recommend it to anyone."

If you want a nourishing hair growth treatment, consider this oil, which many Amazon shoppers recommend for natural hair. The formula includes natural oils like coconut, olive, and jojoba, as well as other vitamin-rich ingredients like mushroom, chickpea, and lentil extracts.

"My edges were gone, as in [non] existent. After just four weeks of using this product, as directed, there is already peach fuzz and my hairline is filling in," wrote one shopper. "If you suffer hair loss this product is a must."

This DHT-blocking hair serum includes a number of powerful natural ingredients, including saw palmetto, horsetail extract, zinc, and green tea extract. The brand even offers a 100% money-back guarantee if you don't see results, which it says can usually take up to three months.

"I can tell you without a doubt that this is a GAME CHANGER. No more falling out, no more shedding (maybe 3-8 strands per wash compared to the 50-70 strands per wash)," wrote one reviewer. "I would recommend this product to anyone experiencing hair loss, extensive shedding due to health reasons etc. Best and ONLY product out there that does exactly what it says it does."

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