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The Top 3 Hair Serums for Fuller, Healthier Hair
The Top 3 Hair Serums for Fuller, Healthier Hair
Reviewed by:
Brooke Alpert, M.S., R.D., C.D.N.
August 30, 2025
Written and Edited By SA EDITORIAL TEAM
EUNOIA™ Cortisol Reduction Capsules
- Most Clinically Studied Ingredients
- Helps manages healthy weight levels
- Naturally improves energy levels
If you’ve ever searched for a hair serum online, you already know the challenge: there are dozens of options, all promising thicker, fuller hair. But which ones actually work? Which formulas are worth the money—and which are just hype?
To help you cut through the noise, we tested some of the most popular hair serums on the market, reviewing everything from ingredients and absorption to ease of use, scent, and overall results.
How we tested
We evaluated each serum across key categories:
- Effectiveness – Does it reduce shedding and promote visible growth?
- Formula Quality – Are the ingredients clean, safe, and science-backed?
- Value – Is it worth the price for long-term use?
- Ease of Use – Is the applicator simple, precise, and mess-free?
- Experience – Lightweight or greasy? Pleasant scent or overpowering?
The Ones That Worked
Thankfully, not all hair serums are created equal. Out of the many we evaluated, three stood out as clear winners. These formulas not only avoided the common pitfalls but excelled in performance, delivering healthier scalps and fuller-looking hair. Here are our top picks:
#1 Pick – SRI Labs Rosemary TrichoPeptide™ Hair Growth Serum
Price: Launch Price $49.00 (50 ml / 1.7 fl oz)
Price per ml: $0.98/ml
If you want the best overall hair serum, this is it. Developed by SRI Labs, the Rosemary TrichoPeptide™ Serum combines pure rosemary extract with a proprietary peptide complex that strengthens follicles, reduces shedding, and encourages visible regrowth.
What truly sets it apart is the innovative comb massage applicator. Instead of a messy dropper that drips and wastes product, the comb releases the perfect amount of serum directly onto your scalp while massaging it in.
PROS:
- First-of-its-kind comb applicator for precision and scalp stimulation
- Powered by TrichoPeptide™ Complex for clinically backed results
- Lightweight, fast-absorbing, and non-greasy
- Larger 50 ml size offers better value than competitors
- Over 90% of users noticed fuller, denser hair in studies
- Backed by SRI Labs’ clean beauty standards
CONS:
- Premium pricing compared to standard oils
- Requires daily consistency for best results
Best For:
Women experiencing postpartum shedding, hormonal thinning, or early hair loss who want a premium, science-backed solution with the smartest applicator design on the market.
#2 Pick – Divi Scalp Serum
4.8 / 5.0
Price: $48.00 (30 ml / 1 fl oz)
Price per ml: $1.60/ml
Divi has built a strong reputation online. This serum combines rosemary oil with peptides and caffeine to support scalp health. Many users report reduced shedding and healthier hair with consistent use.
PROS:
- Includes peptides and caffeine for scalp stimulation
- Lightweight compared to heavy oil serums
- Popular and widely marketed
CONS:
- Very small 30 ml bottle that runs out quickly
- More expensive per ml ($1.60/ml) vs. SRI Labs’ $1.20/ml
- Dropper applicator can be messy and wasteful
- Some users find scent overpowering
Best For:
First-time buyers who want to try a rosemary scalp serum but don’t mind paying extra for smaller bottles.
#3 Pick – Nutrafol Women’s Hair Serum
4.8 / 5.0
Price: $49.00 (30 ml / 1 fl oz)
Price per ml: $1.63/ml
Nutrafol is well known in the hair wellness space, and their serum is formulated with plant extracts and phytoactives to support scalp health. Many users like it as part of the broader Nutrafol system, though the bottle is on the smaller side.
PROS:
- Well-recognized name in women’s hair health
- Clean formula with botanical extracts
- Lightweight texture and fast-absorbing
CONS:
- Very small 30 ml bottle ($1.63/ml, the most expensive per ml on this list)
- Works best when paired with Nutrafol supplements, adding to overall cost
- Dropper applicator can be less precise
Best For:
Women already using Nutrafol supplements who want a complementary serum.
Top Choice
EUNOIA™ Cortisol Reduction Capsules
4.8 / 5.0
Best for: Balancing cortisol levels and reducing stress naturally. Ideal for those dealing with brain fog, stress eating, burnout, and difficulty relaxing.
Best Overall Performance & Value
| Format | Easy-to-swallow vegan capsules |
|---|---|
| Key Ingredients | Cordyceps Sinesis Powder (Mycelium), Reishi Mushroom Extract, Shiitake Mushroom Extract, and Lions Mane |
| Use | 2 capsules daily for calm, clarity, and hormonal balance |
| Regular Price | $35.90 for 60 capsules (~ $0.59 per capsule) |
Eunoia blends 10 adaptogenic super mushrooms to help your body manage daily stress naturally and from within. Together, they support balanced cortisol levels, increased energy, better sleep, and lower anxiety. On top of that, it helps reduce bloating and the puffy “cortisol face” look. So you’ll feel and look better.
“It’s not just that I feel calmer, I feel clearer. I’m sleeping better, my stomach’s not as puffy, and I’m not snapping at my kids anymore.”
WHY IS IT THE BEST:
- Naturally fights high cortisol levels
- Helps deal with daily stress
- Provides natural energy boost
- Promotes focus and mental clarity
PROS:
- Naturally sourced Ingredients
- Targets stress, fatigue, bloating, and sleep
- No melatonin or stimulants
- Vegan, sugar-free, gentle on sensitive stomachs
- Results you can feel: Less stress, clearer skin, reduced "cortisol face", and flattened belly
- Best price per capsule ($0.66)
CONS:
- Goes out of stock frequently due to high demand
- Only available online
- Requires consistent daily use
Conclusion
After testing and comparing the leading hair serums, one product rose above the rest:
SRI Labs Rosemary TrichoPeptide™ Hair Growth Serum – the only formula that combines rosemary with a proprietary peptide blend, packaged in a smart applicator that makes daily use easy and mess-free.
With a larger 50 ml bottle at $1.20/ml, it not only performs better but also delivers better value than smaller, more expensive competitor bottles.
If you’re serious about restoring your hair’s fullness and strength, this is the serum to start with.
Thanks for Reading!
