Key Takeaways

• Trybello uses plant-based actives, Amika focuses on volumizing proteins, and OUAI employs a skincare-inspired adaptogen and peptide blend for scalp health.
• Pricing varies significantly, ranging from $38 to $54 per bottle, with Trybello providing a cost-effective subscription model for long-term hair maintenance.
  
• Trybello and OUAI promise results within 90 to 120 days, while Amika focuses on immediate volume rather than a specific growth timeline.
• Every serum compared is vegan and cruelty-free, excluding harmful ingredients like parabens to ensure a safe and ethical approach to hair care.
• Trybello promotes its doctor-formulated Hair Helper Spray, featuring a 100% plant-based formula and a risk-free 120-day money-back growth guarantee.

How Do I Choose the Best Hair Growth Serum?

Choosing the right hair serum can feel overwhelming with so many options on the market. A few key factors can help narrow down the search.

First, look at the ingredients: plant-based, naturally derived actives like biotin, caffeine, and nourishing oils tend to work with your hair's biology rather than against it.

Second, consider the formula's philosophy: is it free from hormones, silicones, and harsh chemicals?

Third, a brand that stands behind its product with a results guarantee signals real confidence in what it delivers.

And finally, pricing matters, but not in the way you might think. The cheapest option isn't always the best value, and a premium product with high-end ingredients can often deliver far more meaningful results per dollar spent.

With those criteria in mind, let's take a close look at how Trybello Hair Helper Spray, Amika 3D Daily Thickening Treatment, and OUAI Scalp Serum measure up.

“Doctor-Approved Natural Spray Rapidly Boosts Growth & Thickness.
Why 100,000+ Women Are Switching to Trybello!"

Join over 100,000 happy customers who've transformed their hair with our doctor-formulated spray in just 12 weeks, rated 4.8/5 by 40,000+ real users.

Proven Natural Ingredients

• • Caffeine Extract – Blocks DHT and boosts blood flow to follicles
• • Biotin – Direct scalp absorption, no pills needed
• • Castor Oil – Soothes inflammation and locks in moisture
• • Rice Water Extract – Strengthens hair and reduces shedding

120-Day Growth Guarantee: No results? 100% money back, no questions asked.

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Trybello Hair Helper Spray

Trybello's Hair Helper Spray uses biotin, caffeine, and castor oil to target hair growth directly at the scalp.

At Trybello, we developed our Hair Helper Spray to deliver real, visible results using a formula rooted in nature and backed by science. Our spray is built around three powerhouse ingredients that work together to nourish hair from the follicle to the tip.

Biotin strengthens hair at the scalp level, helping to reduce shedding and support follicle health. Caffeine extract boosts blood circulation to the scalp, helping extend the active growth phase of hair and delivering vital nutrients where they're needed most. Castor oil soothes and deeply hydrates the scalp, creating the ideal environment for hair to thrive.

Beyond those star players, our Hair Helper Spray also features argan oil, rice ferment filtrate, and ginger extract, all working in harmony to revitalize and strengthen strands. The entire formula is plant-based, vegan, and completely free of hormones, silicones, parabens, and gluten.

Proudly headquartered in Miami, FL, Trybello is a US-based company. Our Hair Helper Spray is priced at $49.97 for a 30-day supply. We also offer a subscription option at $39.98 for a 30-day supply for those who want to maintain their results with regular deliveries. Most importantly, every bottle is backed by our 120-day complete growth guarantee: grow and shine or get your money back.

Amika 3D Daily Thickening Treatment

Amika's 3D Daily Thickening Treatment targets flat or fine hair with Redensyl™ and rice protein to boost volume at the root. (Image source: Amika)

Amika's 3D Daily Thickening Treatment is a leave-in scalp spray designed for flat or fine hair types looking for the appearance of thicker, denser hair. The formula centers on Redensyl™, a patented blend of larch wood extract and green tea leaf extract that sets the foundation for thicker-looking hair.

Supporting that are hydrolyzed rice protein, which is naturally rich in amino acids and can improve hair volume and manageability, and hydrolyzed vegetable protein, which consists of tiny molecules that help volumize strands. Like all Amika products, it also contains their signature sea buckthorn, an omega-rich superfruit known for nourishing hair and scalp.

The product is free of sulfates, parabens, phthalates, gluten, and mineral oil. It is also vegan and cruelty-free. The 3D Daily Thickening Treatment is priced at $38 for 4 fl oz (120 ml) and is applied 1–2 times daily on dry or towel-dried hair, focusing on the root and scalp area. Amika does not appear to offer a specific satisfaction or results guarantee for this product.

OUAI Scalp Serum

OUAI's Scalp Serum takes a skincare-first approach, using adaptogens, hyaluronic acid, and peptides to support fuller-looking hair. (Image source OUAI)

OUAI's Scalp Serum takes a skincare-inspired approach to hair health, focusing on creating a balanced, hydrated scalp as the foundation for stronger-looking hair. The formula features an adaptogenic blend of Arctic root (Rhodiola rosea), Siberian ginseng, and chaga mushroom, which aim to promote scalp hydration and support a healthy barrier.

Hyaluronic acid adds a moisture-retention component, while peptides (specifically acetyl tetrapeptide-3) and red clover flower extract work to support the appearance of fuller, thicker hair. OUAI's own 16-week expert grading study of 32 subjects reported that 100% of users showed improvement in the look of fuller, thicker hair.

The serum is free of SLS, SLES, parabens, phthalates, and gluten. It is vegan, cruelty-free, and safe for color-treated and chemically-treated hair. OUAI Scalp Serum is priced at $54 for 2 fl oz (60 ml) and is applied daily as a leave-in product directly to the scalp. OUAI does not appear to offer a specific results guarantee for this product.

When Can I Expect to See Hair Growth Results?

Hair strengthening and thickening take time; that's just how the growth cycle works. But each of these products sets different expectations.

With our Trybello Hair Helper Spray, many customers begin to notice reduced shedding and early signs of improvement within the first 4 weeks of consistent use. Visible thickening and fuller-looking hair typically become more apparent around the 8–12 week mark, with the most significant results showing by 120 days. That's exactly why we built our guarantee around that timeline; we know consistency pays off.

Amika recommends using its 3D Daily Thickening Treatment 1–2 times per day for best results, though it does not provide a specific timeline for when users can expect visible changes. The product is positioned as a daily volumizing foundation step rather than a results-over-time growth serum.

OUAI's Scalp Serum recommends daily application and references results in as early as 90 days. Their 16-week study on 32 subjects showed that 100% of participants demonstrated improvement in the appearance of fuller, thicker hair, suggesting a 3–4 month commitment is ideal.

Comparison Table

Why Trybello Hair Helper Spray Stands Out

Real users like Silvana R. are already seeing baby hairs grow back after switching to Trybello's plant-based Hair Helper Spray.

All three serums bring something to the table, but at Trybello, we believe our Hair Helper Spray offers a combination that's hard to match.

Our formula is 100% plant-based, blending biotin, caffeine, and castor oil with argan oil, rice ferment filtrate, and ginger extract to target hair health from every angle: follicle strengthening, scalp nourishment, and circulation support. There are no hormones, no silicones, no parabens, and no synthetic chemicals. Just high-quality, naturally derived ingredients that work with your hair's biology.

We stand behind every bottle with our 120-day complete growth guarantee. Grow and shine or get your money back. We're confident you'll love the results, and over 200,000 happy customers already do.

To get the most out of your Trybello hair care routine, pair our Hair Helper Spray with our shampoo, conditioner, daily boosters, and lash and brow serums for a truly complete regimen.

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Frequently Asked Questions (FAQs)