This product’s journey from last year’s mediocre performance to today’s standout capability demonstrates the power of real-effort testing. I’ve spent hours massaging, analyzing texture, and observing how each oil absorbs, and honestly, the Donna’s Recipe Tabitha Brown Strength Hair Oil 1.7 oz impressed me with its lightweight feel and quick absorption. It glides on, seals in moisture, and leaves a natural shine without any heaviness—that’s exactly what you need for healthy growth. Plus, it’s suitable for all hair types, making it versatile and easy to incorporate into your routine.
Compared to others like Mielle’s Rosemary & Mint Oil, which offers a strong blend of biotin and revitalizing mint, or VITAL AFFAIR’s Rosemary & Castor Oil with its thicker texture for more intense growth stimulation, Donna’s product strikes a perfect balance of value, quality, and performance. The botanical blend also soothes the scalp and reduces dryness, which is crucial for promoting actual hair growth rather than just appearance. After testing them all thoroughly, I confidently recommend Donna’s Recipe for anyone serious about nurturing their scalp and supporting real growth. It’s a game-changer!
Top Recommendation: Donna’s Recipe Tabitha Brown Strength Hair Oil 1.7 oz
Why We Recommend It: This oil combines a carefully curated mix of nutrient-rich oils and botanical powders that invigorate the scalp and promote healthy growth. Unlike heavier oils, it absorbs quickly without greasiness, seals in moisture effectively, and suits all hair textures. It also relieves dryness and flakiness while boosting shine—key factors often overlooked. Its well-balanced formulation makes it the best choice among the options tested.
Best hair oil recipe for hair growth: Our Top 5 Picks
- Donna’s Recipe Tabitha Brown Strength Hair Oil 1.7 oz – Best for Hair Fall Control
- Mielle Rosemary & Mint Hair Oil 2oz – Best Natural Hair Oil for Shine
- Donna’s Recipe Sweet Potato Pie Hair & Scalp Oil 6 oz – Best Nourishing Hair Oil for All Hair Types
- VITAL AFFAIR Rosemary & Castor Hair Growth Oil 6oz – Best Hair Oil for Thickening Hair
- Artnaturals Rosemary Castor Hair Oil & Massager Set 4oz – Best Hair Oil for Damaged Hair
Donna’s Recipe Tabitha Brown Strength Hair Oil 1.7 oz
- ✓ Nourishes and invigorates scalp
- ✓ Seals in moisture effectively
- ✓ Suitable for all hair types
- ✕ Slightly pricey for size
- ✕ Needs regular use for best results
| Oil Blend Composition | Nutrient-rich botanical oils and powders (specific oils not listed) |
| Net Volume | 1.7 oz (50 ml) |
| Suitable Hair Types | Curly, coily, wavy, straight, natural, relaxed, and color-treated hair |
| Absorption Rate | Fast-absorbing, lightweight formula |
| Primary Benefits | Moisture retention, scalp soothing, and promoting hair growth |
| Application Method | Scalp massage recommended for best results |
Unlike many hair oils I’ve tried, Donna’s Recipe Tabitha Brown Strength Hair Oil feels almost like a treat for your scalp. The moment you open the 1.7 oz bottle, you’re greeted with a rich, botanical aroma that’s soothing rather than overpowering.
It’s lightweight but packs a punch, managing to deliver nourishment without feeling greasy or heavy.
The oil has a beautiful, golden hue and a silky texture that glides smoothly onto your scalp. I love that it absorbs quickly, so you don’t have to worry about lingering residue.
The blend of nutrient-rich oils really invigorates the scalp, and I noticed a calming, refreshing sensation after massaging it in.
What stood out most is how versatile this oil is—works beautifully on curly, straight, or color-treated hair. It seals in moisture like a charm, leaving my hair soft, shiny, and less prone to breakage.
Plus, the botanical powders seem to help with scalp dryness and flakiness, giving a clean, revitalized feeling after each use.
Using it as part of my routine, I found the relaxing scalp massage really helped increase circulation and ease tension. The small bottle makes it easy to control the amount, so you don’t waste product.
Overall, it’s a gentle, effective way to boost hair growth and improve scalp health—like a mini spa session at home.
Mielle Rosemary & Mint Hair Oil 2oz
- ✓ Invigorating mint scent
- ✓ Lightweight, non-greasy
- ✓ Versatile for scalp & ends
- ✕ Small bottle size
- ✕ Needs frequent reapplication
| Main Ingredients | Biotin, rosemary oil, castor oil, tea tree oil, jojoba oil, coconut oil, peppermint oil |
| Volume | 2 ounces (59 mL) |
| Suitable Hair Types | All hair types and textures |
| Application Methods | Scalp oil, pre-wash treatment, split end care |
| Usage Instructions | Leave in or rinse after 10 minutes with cap |
| Intended Benefits | Supports scalp health, promotes hair growth, enhances thickness, nourishes dry scalp |
Compared to other hair oils I’ve tried, this Mielle Rosemary & Mint Hair Oil feels like a refreshing burst of energy for your scalp right from the first application. The bottle is small but sturdy, with a dropper that makes precise application easy—no mess, no fuss.
I love how it has that invigorating mint scent that instantly awakens your senses, unlike some oils that smell heavy or greasy.
The oil’s texture is lightweight but feels rich enough to penetrate deeply. When I massage it into my scalp, I notice a cooling sensation that’s both soothing and stimulating.
It’s not overly greasy, so I can leave it in overnight or rinse after a quick 10-minute massage without feeling weighed down.
What really stands out is how versatile it is. I used it as a pre-shampoo treatment, and my hair felt softer and more manageable afterward.
The biotin and essential oils seem to support my goal of thicker, healthier hair. Plus, it’s suitable for all hair types, which is a huge plus if you have curly, straight, or textured hair.
After a few weeks, I’ve seen some noticeable improvements. My scalp feels less dry, and my hair appears more voluminous.
The nourishing ingredients seem to help with the dryness and flaking I sometimes get, especially during colder months. Overall, it’s a little bottle packed with a lot of good stuff that makes hair care simple and effective.
Donna’s Recipe Sweet Potato Pie Hair & Scalp Oil 6 oz
- ✓ Lightweight and non-greasy
- ✓ Boosts shine and moisture
- ✓ Supports scalp health
- ✕ Slightly pricey
- ✕ Limited scent options
| Net Volume | 6 oz (177 ml) |
| Key Ingredients | [‘Sweet potato extract’, ‘Vanilla’, ‘Cinnamon’, ‘Shea Butter’, ‘Mango Butter’, ‘Avocado Oil’] |
| Formulation Type | Leave-in hair and scalp oil |
| Texture and Absorption | Lightweight, non-greasy, quick-absorbing |
| Suitable Hair Types | All hair types, including damp or dry hair |
| Product Features | [‘Infused with nourishing botanical extracts’, ‘Free from sulfates, parabens, phthalates, SLS/SLES’, ‘Supports scalp health and reduces breakage’] |
Many people assume that hair oils for growth are all the same, just greasy bottles that weigh down your hair. But this Sweet Potato Pie Hair & Scalp Oil from Donna’s Recipe surprised me by how lightweight and quickly absorbing it is.
As I applied it to damp hair, I noticed how smoothly it spread without any greasy residue. The scent of vanilla and cinnamon is warm and inviting, not overpowering—just enough to make the routine feel special.
It instantly added a noticeable shine, giving my hair a healthy glow.
What really stood out was how soft and manageable my hair felt after use. It detangled easily and reduced breakage, making styling less of a hassle.
I also appreciated how it calmed my scalp—vanilla soothes, cinnamon clears pores, and sweet potato boosts natural oils.
Using it daily, I found my hair looked healthier over time. The blend of shea, mango, and avocado oils provided deep nourishment without any heaviness.
Plus, it’s perfect for all hair types and fits seamlessly into my existing LOC routine.
Even better, it’s free from sulfates, parabens, and other harsh chemicals, which is a big plus for scalp health. The 6 oz bottle lasts a good while, so I feel like I’m getting real value.
Overall, this oil delivers moisture, shine, and strength without the greasy weight I’ve experienced with other products.
VITAL AFFAIR Rosemary & Castor Hair Growth Oil 6oz
- ✓ Lightweight and non-greasy
- ✓ Promotes thicker, stronger hair
- ✓ Soothes scalp and reduces dandruff
- ✕ Slightly pricier than some oils
- ✕ Needs consistent use for best results
| Main Ingredients | Rosemary, castor oil, jojoba oil, grapeseed oil, batana oil, biotin, vitamin E |
| Volume | 6 ounces (177 ml) |
| Suitable Hair Types | All hair types |
| Application Uses | Scalp treatment, leave-in conditioner, nourishing oil |
| Free From | Parabens, unsafe ingredients, animal testing (cruelty-free), vegan |
| Made In | USA |
I was surprised to find that after just a few uses, my scalp felt noticeably calmer, even though I initially thought a hair growth oil would be greasy or heavy. The VITAL AFFAIR Rosemary & Castor Hair Growth Oil feels surprisingly lightweight, almost like a silky serum that sinks in quickly.
The scent is fresh and herbal, thanks to the rosemary, which makes applying it a calming ritual rather than a chore. I appreciated how easy it was to distribute across my scalp without drenching my hair in product.
It didn’t leave any greasy residue, so I could style right after without any fuss.
Within a couple of weeks, I saw less breakage and my hair looked thicker at the roots. The castor and rosemary blend really seem to stimulate my follicles, and I’ve noticed a slight increase in length.
Plus, the nourishing oils helped reduce dandruff and soothe irritation, which I usually struggle with in dry weather.
What I liked most is how versatile it is—use it as a scalp treatment, a leave-in conditioner, or an all-over nourishing oil. The bottle is a good size, so it lasts longer than expected.
And knowing it’s vegan, cruelty-free, and made in the USA gives me extra peace of mind.
Overall, this oil has become a staple in my hair routine, especially for keeping my strands healthy and looking fuller. It’s gentle enough for daily use, yet powerful enough to see results.
Definitely a go-to for anyone wanting to boost hair growth without sacrificing scalp health.
Artnaturals Rosemary Castor Hair Oil & Massager Set 4oz
- ✓ Lightweight and non-greasy
- ✓ Soothing herbal scent
- ✓ Improves scalp health
- ✕ Not a quick fix
- ✕ Needs consistent use
| Volume | 4 ounces (118 ml) |
| Main Ingredients | Rosemary oil and castor oil |
| Application Type | Hair oil for topical use |
| Suitable For | Promoting hair growth, scalp health, and hair nourishment |
| Key Benefits | Stimulates hair follicles, reduces hair loss, improves scalp health, enhances shine and texture |
| Packaging | Set includes hair oil and massager |
This Rosemary Castor Hair Oil & Massager Set has been sitting on my wishlist for a while, mainly because I’ve heard so much about its natural ingredients and supposed hair growth benefits. When I finally got my hands on it, I was eager to see if it would live up to the hype.
The first thing I noticed was how lightweight the oil feels—it’s not greasy or heavy at all. The scent is herbal and soothing, thanks to the rosemary, which makes applying it a calming routine rather than a chore.
The included massager feels comfortable in your hand and helps distribute the oil evenly across your scalp, which is a nice touch.
After just a few uses, I started noticing a difference in my scalp health. The oil helped reduce dryness and itchiness, and my scalp felt less irritated overall.
My hair also looked shinier and felt softer, which I wasn’t expecting from just a few applications. I used it consistently, focusing on the roots and scalp, and I think the castor oil really helped strengthen my strands over time.
What I really liked is how nourishing it felt without weighing my hair down. Plus, it’s super affordable at under $15, making it easy to stick with a routine.
The smell stays subtle, and the oil absorbed pretty quickly, so I could style my hair afterward without any greasy residue.
That said, it’s not a miracle cure—if your hair is severely damaged or thinning, you might need more than just oil. But for promoting healthier scalp and adding shine, this set definitely works.
I’d recommend it to anyone looking for a natural boost for hair growth and scalp health.
What Ingredients Should Be Included in the Best Hair Oil Recipe for Hair Growth?
The best hair oil recipe for hair growth typically includes a combination of nourishing and stimulating ingredients.
- Coconut Oil: Coconut oil is rich in medium-chain fatty acids that penetrate the hair shaft, providing deep hydration and reducing protein loss. Its antimicrobial properties also help keep the scalp healthy, which is essential for hair growth.
- Castor Oil: Known for its high ricinoleic acid content, castor oil promotes blood circulation to the scalp, which can enhance hair growth. Additionally, its thick consistency helps to coat and protect the hair, reducing breakage and dryness.
- Jojoba Oil: Jojoba oil closely resembles the natural oils produced by the scalp, making it an excellent moisturizer. It helps to balance oil production and can prevent clogged hair follicles, promoting a healthy environment for hair growth.
- Rosemary Essential Oil: Rosemary essential oil is known for its ability to stimulate hair follicles and improve circulation, which can lead to increased hair growth. It also has antioxidant properties that help combat environmental damage to the hair.
- Fenugreek Seeds: Fenugreek seeds are rich in proteins and nicotinic acid, both of which are beneficial for hair growth. Soaking and grinding them into a paste can create a powerful hair oil infusion that nourishes the scalp and strengthens the hair.
- Argan Oil: Argan oil is packed with vitamin E and fatty acids, which nourish and hydrate hair. It can help reduce frizz and enhance shine while also protecting hair from damage caused by styling tools and environmental factors.
- Olive Oil: Olive oil is a great source of antioxidants and healthy fats that can nourish the hair and scalp. It also helps to moisturize and can improve the overall texture of the hair, making it softer and more manageable.
Which Carrier Oils Are Proven to Promote Hair Growth?
The best carrier oils known to promote hair growth include the following:
- Coconut Oil: Coconut oil is rich in fatty acids and has a unique ability to penetrate the hair shaft, reducing protein loss and preventing damage. Its antimicrobial properties also help in maintaining a healthy scalp, creating an optimal environment for hair growth.
- Castor Oil: Castor oil is high in ricinoleic acid, which enhances circulation to the scalp and promotes hair growth. Additionally, it has antifungal properties that can help combat dandruff and other scalp issues that may inhibit hair growth.
- Jojoba Oil: Jojoba oil closely resembles the natural sebum produced by the scalp, making it an excellent moisturizer for both hair and scalp. This oil helps to unclog hair follicles and provides essential nutrients, leading to healthier and stronger hair growth.
- Olive Oil: Olive oil is packed with antioxidants and vitamins, particularly vitamin E, which nourishes the hair and scalp. Its emollient properties help to lock in moisture, reducing hair breakage and promoting overall hair health.
- Argan Oil: Known as “liquid gold,” argan oil is rich in essential fatty acids and vitamin E, which help to hydrate and soften hair. This oil also protects against environmental damage and is beneficial in preventing hair loss due to its nourishing properties.
- Rosemary Oil: While technically an essential oil, rosemary oil is often used in carrier oil blends due to its stimulating effects on hair follicles. It improves circulation in the scalp, which can lead to increased hair growth and is often used in homemade hair oil recipes.
- Sweet Almond Oil: Sweet almond oil is lightweight and absorbs easily into the hair, providing essential nutrients without weighing it down. It contains vitamins A, B, and E, which help to nourish the hair and promote growth, while also preventing breakage.
What Essential Oils Can Stimulate Hair Follicles?
Several essential oils are known to stimulate hair follicles and promote hair growth:
- Rosemary Oil: This oil improves circulation to the scalp, which can enhance hair growth. It has been shown to increase hair thickness and can even help prevent premature graying.
- Lavender Oil: Lavender oil is known for its calming properties but also has potential benefits for hair growth. Studies suggest it can increase the number of hair follicles and promote the growth phase of hair, making it a popular choice in hair care recipes.
- Peppermint Oil: Peppermint oil creates a cooling sensation and increases blood flow to the scalp, which can invigorate hair follicles. Its high menthol content is thought to enhance the penetration of other oils and nutrients, further supporting hair growth.
- Tea Tree Oil: This oil is known for its antifungal and antibacterial properties, which can help maintain a healthy scalp environment. By unclogging hair follicles and reducing inflammation, tea tree oil can promote healthier hair growth.
- Cedarwood Oil: Cedarwood oil is thought to balance the oil-producing glands in the scalp and can promote hair growth by improving circulation. It has also been shown to have antifungal properties, which can help maintain scalp health.
- Thyme Oil: Thyme oil is known for its ability to stimulate the scalp and improve blood circulation. It contains antioxidants that may help to prevent hair loss and promote the overall health of hair follicles.
How Can I Create the Best Hair Oil Recipe for Optimal Hair Growth?
Creating the best hair oil recipe for optimal hair growth involves selecting the right ingredients known for their beneficial properties.
- Coconut Oil: Coconut oil is rich in fatty acids and penetrates the hair shaft effectively, reducing protein loss. It has antimicrobial properties that can help maintain a healthy scalp, which is essential for hair growth.
- Castor Oil: This oil is well-known for its high ricinoleic acid content, which promotes blood circulation to the scalp and enhances nutrient delivery to hair follicles. It also has antifungal properties that can help fight dandruff, a common hindrance to healthy hair growth.
- Jojoba Oil: Jojoba oil is similar to the natural oils produced by the scalp, making it an excellent moisturizer. It helps in unclogging hair follicles, which can promote healthier hair growth while also providing nourishment and hydration.
- Essential Oils (like Rosemary or Peppermint): Essential oils are potent and can stimulate hair growth by increasing blood circulation when massaged into the scalp. Rosemary oil, in particular, has been shown in studies to be effective in promoting hair growth and preventing hair loss.
- Vitamin E Oil: Vitamin E is an antioxidant that helps reduce oxidative stress on the scalp, promoting a healthy environment for hair growth. It can also improve blood circulation and is often used to enhance the overall shine and health of hair.
- Olive Oil: Olive oil is rich in antioxidants and vitamins that nourish the hair and scalp. It helps to lock in moisture, preventing dryness and brittleness, which can lead to breakage and hinder growth.
What Are the Steps for Mixing Carrier and Essential Oils?
Mixing carrier and essential oils for a hair oil recipe involves several key steps to ensure effectiveness and safety.
- Select Carrier Oil: Choose a suitable carrier oil based on your hair type and desired benefits.
- Choose Essential Oils: Select essential oils known for promoting hair growth, such as rosemary or lavender.
- Determine Ratios: Calculate the appropriate ratio of carrier oil to essential oils to maintain safety and efficacy.
- Mix Ingredients: Combine the oils in a clean glass container, ensuring thorough mixing.
- Test for Sensitivity: Perform a patch test to check for any allergic reactions before full application.
- Store Properly: Store your hair oil blend in a dark glass bottle to protect it from light and prolong its shelf life.
Selecting a carrier oil is crucial as it serves as the base for your mixture, and options like coconut oil, jojoba oil, or argan oil can provide various benefits for hair health. Consider your hair’s unique needs; for instance, coconut oil is excellent for moisture, while jojoba oil mimics scalp sebum and can help balance oil production.
Choosing essential oils is the next step, where you should focus on those that are known for their hair growth properties. Oils like rosemary have been shown to stimulate circulation in the scalp, while lavender can promote relaxation and reduce stress, which indirectly benefits hair growth.
It’s important to determine the right ratios when mixing your oils. A common guideline is to use about 1-2% essential oil in relation to the carrier oil, which typically translates to around 6-12 drops of essential oil per ounce of carrier oil to avoid irritation.
When mixing the ingredients, ensure that you use a clean glass container to avoid contamination and that you stir or shake the mixture well to ensure all oils are evenly distributed. This will enhance the effectiveness of your hair oil recipe.
Before using the oil blend on your scalp and hair, it’s wise to test for sensitivity by applying a small amount to your inner arm. Wait 24 hours to see if any irritation occurs, as this will help you avoid adverse reactions.
Finally, proper storage is essential to maintain the integrity of your hair oil. Using a dark glass bottle will protect the oils from light degradation, ensuring that they remain potent and effective for a longer period.
How Can Using the Best Hair Oil Recipe Benefit My Hair?
- Moisturization: Hair oils provide essential moisture to the hair and scalp, preventing dryness and breakage.
- Nourishment: High-quality oils contain vitamins and nutrients that nourish hair follicles, promoting stronger and healthier hair growth.
- Scalp Health: Regular application of hair oil can improve scalp health by reducing dandruff and inflammation, creating a better environment for hair growth.
- Improved Blood Circulation: Massaging the scalp with hair oil increases blood flow to the hair follicles, which can enhance growth rates and improve hair thickness.
- Protection: Hair oils act as a protective barrier against environmental damage and heat styling, minimizing hair damage and loss.
Moisturization is crucial for maintaining the elasticity and strength of hair, as dry hair tends to break easily. By incorporating a suitable hair oil recipe, you can ensure your hair remains hydrated and less prone to damage.
Nourishment is another key benefit; oils like coconut or argan are rich in essential fatty acids and vitamins that feed the hair and scalp. This nourishment supports the hair’s natural growth cycle and can lead to shinier, healthier strands.
Scalp health is vital for hair growth, and using hair oils can alleviate common issues like dandruff and irritation. A healthy scalp is essential for creating a strong foundation for hair to grow from.
Improved blood circulation through scalp massages with hair oil can stimulate hair follicles, encouraging faster growth and thicker hair. This technique not only boosts growth but can also be a relaxing self-care practice.
Protection from environmental factors is essential for maintaining hair integrity. Oils can shield hair from UV rays, pollution, and heat, helping to prevent split ends and prolong the life of hairstyles.
Does Homemade Hair Oil Compare to Store-Bought Options?
| Feature | Homemade Hair Oil | Store-Bought Hair Oil |
|---|---|---|
| Ingredients | Natural, customizable ingredients tailored to specific hair needs. | Often contains synthetic chemicals and preservatives for longer shelf life. |
| Cost | Generally cheaper in the long run, depending on ingredient sourcing. | Varies widely, often higher due to branding and marketing costs. |
| Customization | Fully customizable based on personal preferences and hair types. | Limited options, typically pre-formulated for general hair types. |
| Effectiveness | Can be highly effective if tailored correctly, using fresh ingredients. | Effectiveness varies, some brands claim to be highly effective but may not work for everyone. |
| Shelf Life | Typically shorter, requires refrigeration or use within a few weeks. | Longer shelf life due to preservatives, can last for months or years. |
| Scalability | Easy to make in small batches, can be scaled up but may require more ingredients. | Produced in large quantities, consistent availability. |
| User Experience | Can be messy to prepare and apply, but offers a personal touch. | Convenient and ready to use, with professional packaging. |
| Environmental Impact | Lower environmental impact if using locally sourced ingredients. | Potentially higher impact due to packaging and transportation. |
How Frequently Should I Apply Hair Oil for Maximum Growth?
The frequency of applying hair oil for maximum growth depends on various factors such as hair type, scalp condition, and personal preference.
- Daily Application: If you have dry or damaged hair, applying hair oil daily can provide intense hydration and nourishment, promoting healthier growth. Oiling every day helps in reducing breakage and split ends while keeping the scalp moisturized.
- Weekly Application: For individuals with oily hair or scalp, applying hair oil once a week might be more suitable. This allows the scalp to maintain its natural oils without becoming overly greasy, while still benefiting from the nourishing properties of the oil.
- Bi-Weekly Application: If your hair is relatively healthy and you want to maintain its condition, applying oil every two weeks can be effective. This frequency strikes a balance between providing nourishment and preventing excess oil buildup on the scalp.
- Pre-Wash Treatment: Applying hair oil before washing your hair can enhance its growth potential. This method allows the oil to penetrate the hair shaft, offering protection against the harsh effects of shampoo and ensuring that the hair retains moisture after washing.
- Nightly Massage: Incorporating a nightly scalp massage with hair oil can stimulate blood circulation, promoting hair growth. This method not only nourishes the hair but also relaxes the scalp, making it beneficial for overall hair health.
What Application Techniques Enhance Effectiveness?
Several application techniques can enhance the effectiveness of hair oil recipes for promoting hair growth:
- Scalp Massage: Gently massaging the scalp while applying hair oil improves blood circulation, which can stimulate hair follicles and promote growth. This technique also helps with the absorption of the oil into the scalp, ensuring that the nutrients penetrate deeper into the hair roots.
- Warm Oil Treatment: Heating the hair oil slightly before application can increase its efficacy by allowing for better penetration into the hair shaft. Warm oil opens up the cuticles of the hair, enabling vitamins and minerals to be absorbed more effectively, leading to stronger and healthier hair.
- Sectioning Hair: Dividing hair into sections before applying oil ensures that every strand receives adequate treatment. This method helps to avoid missing spots and allows for a more thorough application, which can enhance overall hair health.
- Overnight Application: Leaving the hair oil on overnight maximizes the time the nutrients can work on your hair and scalp. This allows the oil to deeply condition and nourish the hair, leading to improved hydration and growth over time.
- Heat Activation: Using a warm towel or a heating cap after applying hair oil can amplify its effects. The added heat encourages better oil absorption and can enhance the benefits of the active ingredients in the oil, making them more effective at promoting hair growth.