By Niki Galvez, Hairstylist & Trichologist Trainee
First, let's redefine "best for growth" (because the internet has this wrong)
No oil on this planet makes your hair grow faster, but the right oil can help you keep every centimetre you're already growing. Your scalp produces about 12 cm of hair per year regardless of what you put on it.1 That rate is set by your biology, not your product shelf.
So why does your hair never seem to get longer?
Breakage. That's it. Your hair IS growing. It's just snapping off at the ends before you see the length. The real question isn't "which oil makes hair grow?" It's "which oil prevents the most breakage so I actually retain that growth?"
Why "growth" is the wrong metric (retention is the real game)
Here's a reframe that changed how I approach every client's hair: breakage and hair loss are completely different problems. Hair loss means strands fall from the root (you'll see a white bulb). Breakage means strands snap mid-shaft from dryness, damage, or poor elasticity.
An oil can't fix hair loss. That's a scalp and follicle issue. See a dermatologist for that.
But an oil absolutely can reduce breakage. And less breakage = more visible length over time. That's length retention.
Our evaluation criteria: penetration, protection, strengthening
Not all oils work the same way. Some actually get inside the hair fibre. Others just sit on top. We're ranking these oils on three things:
- Penetration ability: does it reach the cortex, or just coat the surface?
- Protein protection: does it reduce the protein your hair loses every wash?
- Strand strengthening: does it improve elasticity and break resistance?
This is how a trichologist would evaluate oils. Not by TikTok views.
The honest ranking: best hair oil for hair growth (tested by what actually penetrates)
Here's the comparison. Every rating is based on published research, not marketing.
| Oil | Cortex penetration | Protein protection | Ease of use | Best for |
|---|---|---|---|---|
| Coconut oil / coconut lipids | Deep (30–50 µm) | Strong evidence | Raw: tricky. Refined: easy. | Pre-wash length retention |
| Rosemary oil | N/A (essential oil, used on scalp) | Not applicable | Easy (diluted) | Scalp circulation support |
| Castor oil | Limited (thick, heavy) | No direct evidence | Hard to wash out raw | Hydration + elasticity |
| Argan oil | Surface only (0–5 µm) | Minimal | Very easy | Daily finishing + smoothing |
| Jojoba oil | Light surface coating | No direct evidence | Easy | Lightweight daily moisture |
| Peppermint oil | N/A (essential oil) | Not applicable | Easy (diluted) | Scalp tingling sensation |
Coconut oil (and its refined cousin, coconut lipids)
The research favourite, and it's not even close. Coconut oil is the only common oil shown to significantly reduce protein loss in both damaged and undamaged hair.2 Mineral oil and sunflower oil? They don't come close on this metric.3
The reason is molecular: lauric acid has a low molecular weight and a straight chain structure that lets it slip through the cell membrane complex deep into the cortex. Imaging studies confirm coconut oil penetrates 30–50 µm into the hair fibre, while argan barely reaches 5 µm.4
The catch? Raw coconut oil is solid at room temperature and genuinely annoying to wash out. Refined coconut lipids (caprylic/capric triglyceride, the shorter-chain fatty acids found in coconut) give you the same penetration with better usability.5
Rosemary oil
Good for your scalp, but it's doing a completely different job. One study found rosemary oil comparable to 2% minoxidil over six months for hair count.6 That's genuinely interesting. But rosemary is an essential oil applied to the scalp for circulation. It's not a length-protection oil for your mids and ends.
Think of rosemary as a scalp support tool. It doesn't penetrate the hair fibre or reduce protein loss. Different category entirely.
Castor oil
Thick, sticky, and surprisingly popular for zero clinical growth evidence. Castor oil is rich in ricinoleic acid, which supports hydration and may help improve elasticity. But there are no human trials showing it makes hair grow. The "growth" reputation comes from social media, not from a lab.
It IS good for sealing moisture into very dry, coarse hair. Just don't expect miracles. And good luck shampooing it out when you use it raw.
Argan oil
A brilliant finishing oil that doesn't actually get inside your hair. Research shows argan penetrates just 0–5 µm, cuticle surface only.4 That's enough to smooth frizz and add shine, but it won't protect the cortex or reduce protein loss.
Argan is perfect as a post-wash smoothing oil. For pre-wash protection? Not the right pick.
Jojoba oil
Jojoba mimics your hair's natural sebum, which makes it feel lightweight and non-greasy. But there's limited research on deep cortex penetration or protein protection. It's a solid daily conditioner. Just not a treatment-level oil.
Peppermint oil
Like rosemary, peppermint is an essential oil for the scalp. Some early research suggests it may support follicle activity, but evidence is preliminary. It's not a hair fibre oil and shouldn't be applied to lengths.
Single oils vs formulated blends: which approach actually works better?
Single oils work for simple, specific needs, but a formulated blend combines penetrating oils, strengthening actives, and moisture sealants in ratios designed for maximum absorption. That's the difference between a decent pre-wash and a genuinely effective one.
The DIY problem: getting ratios wrong
Mixing your own hair oil sounds fun until you're googling "how to get castor oil out of my hair" at 11pm. Raw oils vary in quality, concentration, and molecular weight. Blending them without understanding how they interact often means some ingredients block others from absorbing properly.
What a trichologist-formulated blend does differently
A good formulated oil pairs penetrating base oils (like coconut lipids) with actives that raw oils simply can't deliver. Peptides, for instance, help strengthen the hair fibre from within7. You can't get that from a bottle of coconut oil, no matter how organic it is. Same goes for niacinamide, which helps lock in moisture along the lengths.
When a single oil is enough (and when it isn't)
Honestly? If you just want a light scalp massage once a week, rosemary oil diluted in a carrier is fine. But if your goal is length retention (reducing protein loss, strengthening the fibre, and preventing the breakage that's stealing your length) a multi-oil formula designed for mids-to-ends protection is going to do more.
JUVA pre-wash hair oil: honest review
JUVA is a trichologist-formulated pre-wash oil for mids to ends. It's built for cortex penetration and protein loss prevention, but it's not a scalp oil or a finishing oil. Let's be transparent about what it does and doesn't do.
What's in it
The formula leads with caprylic/capric triglyceride (refined coconut lipids, the shorter-chain fatty acids that penetrate deepest), the same type of triglyceride shown to restore tensile strength by 29% and increase fibre thickness by over 5% in bleached hair after 21 days.5 Then it layers in sea buckthorn (omega-7 for softness), avocado and olive oils (moderate cortex penetration4), black seed and castor oils (hydration and elasticity), plus squalane (lightweight moisture sealant). The actives (peptides for strand strength and niacinamide for moisture retention) are what separate this from any single-ingredient oil.
What it does well: pre-wash cortex protection
This is where JUVA earns its place. The three-pillar approach: Protects (coconut lipids, shown in research to help reduce protein loss during washing), Elasticizes (peptides improve fibre strength and flexibility), and Conditions (squalane + sea buckthorn seal moisture without heaviness). Coconut lipids help reduce protein loss, peptides support fibre strength, and squalane seals moisture, so your hair may lose less protein and retain more moisture each wash cycle.
Apply 2–3 pumps to mids and ends, let it marinate for at least 20 minutes (or wear the Hot Booster Cap to boost absorption8), then shampoo out.
What it doesn't do
Let's be honest: JUVA isn't a scalp growth serum. It won't replace rosemary oil if scalp circulation is your priority. It's not a finishing oil either. It's designed to wash out, not stay in all day. And the bottle is smaller than budget supermarket options. You're paying for formulation precision, not volume.
Who it's best for
Anyone whose goal is retaining length, reducing breakage, and protecting mids to ends from wash-day damage. Works across hair types, just adjust the pumps (1–2 for fine hair, 4–5 for thick or long hair, depending on how much hair you have).
How to choose the right oil for YOUR hair goal
The right hair oil depends entirely on what you're trying to achieve: scalp support, length retention, daily smoothing, or all three.
If your goal is scalp health: Rosemary or peppermint essential oils (always diluted in a carrier). These support circulation and aren't meant for your lengths.
If your goal is length retention: A pre-wash treatment with cortex-penetrating oils. Coconut lipids, peptides, squalane: ingredients that reduce protein loss and strengthen the fibre before your shampoo strips it. This is where a formula like JUVA's pre-wash oil sits. Check out our full hair oiling guide for the method.
If your goal is daily smoothing: A lightweight finishing oil (argan, jojoba) applied post-wash to damp ends. Great for frizz control, but don't expect it to protect against wash-day damage.
If you want all three: Layer them. Rosemary on scalp, pre-wash oil on lengths before you wash, finishing oil on ends after. Different products for different jobs.
Frequently asked questions about the best hair growth oils
Which oil is best for hair growth?
No oil speeds up how fast your hair grows. That's biology. But coconut oil (and refined coconut lipids) have the strongest evidence for reducing breakage and protein loss, which means you retain more length.2 For a full breakdown of the retention approach, read our article on hair oil for growth.
Does oiling your hair help it grow faster?
Nope. Oiling helps you keep the growth you already have. Pre-wash oiling reduces the damage each wash cycle does to your strands. Less damage = less breakage = more visible length over time.
How often should you use hair growth oil?
For a pre-wash treatment, once or twice a week is a solid starting point. Consistency matters more than frequency. Build it into your hair oiling routine and give it at least 8 weeks before judging results.
Is rosemary oil or coconut oil better for hair growth?
They do completely different things. Rosemary supports scalp circulation. Coconut oil penetrates the hair fibre and reduces protein loss. If you have to choose one for length retention, coconut wins. Ideally? Use both. Rosemary on your scalp, coconut-based oil on your lengths.
What oil penetrates the hair shaft best?
Coconut oil and MCT oil (caprylic/capric triglyceride, the shorter-chain fatty acids derived from coconut) have the deepest documented penetration: 30–50 µm into the cortex.4 Shorter-chain, saturated fatty acids penetrate best because they're compact enough to pass through the cell membrane complex.
This content is for educational purposes and does not constitute medical advice. If you have concerns about hair loss or scalp conditions, please consult a dermatologist or trichologist.
Sources
- Paus R, Cotsarelis G. "The Biology of Hair Follicles." New England Journal of Medicine. 1999;341:491-497. DOI: 10.1056/NEJM199908123410706
- Rele AS, Mohile RB. "Effect of coconut oil on prevention of hair damage. Part I." Journal of Cosmetic Science. 1999;50:327-339.
- Rele AS, Mohile RB. "Effect of mineral oil, sunflower oil, and coconut oil on prevention of hair damage." Journal of Cosmetic Science. 2003;54(2):175-192. PMID: 12715094
- Lourenco CB, et al. "Impact of Hair Damage on the Penetration Profile of Coconut, Avocado, and Argan Oils into Caucasian Hair Fibers." Cosmetics. 2024;11(2):64. DOI: 10.3390/cosmetics11020064
- Kim K-B, Ahn S-Y. "Determination of penetration and protection of fatty acids in bleached hair according to fatty acid chain length and the application to understanding the protective effects of MCT oil and coconut oil." Applied Biological Chemistry. 2023;66:38. DOI: 10.1186/s40691-023-00332-0
- Panahi Y, et al. "Rosemary oil vs minoxidil 2% for the treatment of androgenetic alopecia: a randomized comparative trial." Skinmed. 2015;13(1):15-21. PMID: 25842469
- Malinauskyte E, et al. "Penetration of different molecular weight hydrolysed keratins into hair fibres and their effects on the physical properties of textured hair." International Journal of Cosmetic Science. 2021;43(1):26-37. DOI: 10.1111/ics.12663. PMID: 32946595
- Keis K, Persaud D, Kamath YK, Rele AS. "Investigation of penetration abilities of various oils into human hair fibers." Journal of Cosmetic Science. 2005;56(5):283-295. PMID: 16258695