Here’s How Long to Use Hair Growth Oil for Shampoo Commercial-Level Length & Fullness

Since middle school, my biggest beauty wish has been to have long, flowing hair à la Jennifer Aniston in season six of Friends. Unfortunately, around the same time, I realized that my own fine strands stubbornly refused to grow past my shoulders. However, that’s finally begun to change thanks to my hairstylist’s recent recommendation to use hair growth oil. While this multitasking product can be used for a variety of purposes—boosting moisture, strengthening hair, and protecting against heat damage, to name a few—certain oils also contain ingredients that are proven to promote length and fullness, which means those luscious, shampoo-commercial strands may finally be in reach.

But exactly how long does it take to see noticeable results? Our InStyle team tested a selection of the most popular serums and oils, noting how each applied and performed over the span of 12 weeks. We also spoke with three top hair experts to learn how these can aid in hair growth. Whether you’re looking to increase your length or just achieve a bit of extra body, read on to discover why hair growth oil may be the step your routine has been missing.

How Long Does It Take to See Results With Hair Growth Oil?

While a quality hair growth oil can transform your hair from thinning to full of body, that doesn’t mean it’s an instant miracle worker. “Generally, you can expect to see noticeable results from hair growth oil in about four to 12 weeks,” says Jewell Hingorani, a New York City-based hairstylist and founder of Jewell Clip Luxury Hair Extensions. 

Hair loss is not one problem that fits all: the cause can range from lifestyle—stress levels, consistent wearing of tight hairstyles, or pregnancy— to age or more serious medical issues, such as vitamin deficiencies, thyroid issues and taking certain medications. If yours falls into the latter category, hair oils and scalp serums likely won’t suffice—the underlying condition must be treated first. And if your hair loss is sudden and/or significant (i.e., noticing big clumps in your drain), always consult your doctor. That said, “the timeline [for results] can vary depending on the product and your individual hair growth rate,” Hingorani says.

Timeline of Hair Growth

Here’s what to expect when you first start using a hair growth product, according to Hingorani.

• After 2-4 Weeks: In this initial period, you might notice your scalp feeling healthier and less dry, along with increased shine in your hair. Some users may also observe slight improvements in hair texture and manageability.
• After 4-6 Weeks: As time goes on, you might start spotting tiny new hairs sprouting. Your existing hair may feel stronger and less likely to break, too. 
• After 2-3 Months: By this stage, you may see more significant changes in hair density, with new growth becoming noticeable in previously thinning areas. Overall hair health improves, and shedding may decrease.
• After 6 Months: At this point, you can expect to see substantial hair growth, resulting in fuller and thicker hair. The new growth should be stronger, and any issues with excessive hair loss or thinning may be greatly reduced.
  

Ingredients in Hair Growth Oils and Serums

• Oils: “Rosemary, argan, tea tree, and mineral oils are often reported as effective hair oils [for growth],” explains Brendan Camp, M.D., FAAD, a New York-based double board-certified dermatologist in dermatology and dermatopathology at MDCS Dermatology. The oils strengthen hair by improving moisture and delivering key nutrients, which act as tiny shields against damage. Tea tree oil is also known for its anti-inflammatory, antifungal, and antibacterial properties, explains Camp. While that doesn’t directly cause hair growth, it can create an optimal environment for growth on your scalp. Dr. Camp also touts the benefits of pumpkin seed oil and saw palmetto oil for hair loss: “These oils inhibit an enzyme involved in hair loss.” Preventing hair follicles from shrinking—leading to thinner, shorter hairs—is especially important in the cases of alopecia, or hereditary hair loss.
• Minoxidil:  “Oral minoxidil is used to treat hypertension (high blood pressure), and one of the side effects is hair growth,” explains Dr. Camp. “Topical minoxidil products capitalize on that side effect to influence hair growth.” As an FDA-approved topical solution for hair loss, Angelo David (a New York City-based hairstylist/hair loss expert and founder of the eponymous salon) adds that minoxidil works by widening blood vessels and increasing oxygen and nutrient flow to the hair follicles. “Additionally, it extends the growth phase of the hair cycle while reducing the duration of the resting phase, encouraging faster hair growth.” Minoxidil is commonly available in two percent and five percent strengths, typically in foam or serum form.
• Ketoconazole (Nizoral): To clear up confusion, the antifungal, dandruff-busting medication ketoconazole and Nizoral are the same thing—Nizoral is just the brand name for the over-the-counter shampoo. “Ketoconazole is an antifungal medication used in OTC and prescription shampoos to treat dandruff,” says Dr. Camp. “Some studies suggest ketoconazole may improve hair growth by inhibiting the function of an enzyme called 5-alpha reductase (5AR). This enzyme converts testosterone to dihydrotestosterone (DHT), contributing to hair thinning and loss.”
  

Factors That Impact Results

• Cause of Hair Loss: Perhaps one of the most frustrating aspects of hair loss is that a variety of factors can contribute to it—and it’s not always easy to figure out the root of your specific issue. That said, increased cortisol (that pesky stress hormone), hormone imbalances, and genetic factors can typically be identified as a few key culprits. “Each person has their own situation when it comes to hair loss, like stress, hormonal, and hereditary issues,” says David. “So the best time to use any hair growth treatment is in the early stages, so the shedding will stop or slow down. Everybody will get different results based on their individual situation.”
• Consistency of Use: While certain hair oils may give you quick results in terms of increased shine and hydration, it’s essential to use your chosen product according to its directed usage over time if you want to see lasting change. David advises his clients to think of using hair growth products like going to the gym, or keeping up a regimented skin care routine. “You can’t go into this being a weekend warrior,” he cautions. “It’s not going to work by just using it once. Over time, you’ll start to see the hair getting healthier. But you have to be consistent.”
• Scalp Health: Think of your scalp as the soil of a garden: If you don’t take care of it, how are the flowers (or in this case, hair) supposed to grow healthy and strong? “Using the right things on your scalp is very important to maintain [an optimal environment for growth],” says David. “Certain serums will address the inflammation on your scalp, which provides an immediate feeling of relief from any irritation. Then over time, you’ll hopefully start to see shedding slow down or stop.”
  

Our Favorite Hair Growth Oils & Serums

Out of the 26 products we tested, the following gave our strands the most noticeable boost in new growth, length, and thickness.

Augustinus Bader’s The Hair Oil is formulated with the brand’s signature TFC8 (or Trigger Factor Complex) blend. This carefully designed combo of vitamins, lipids, and peptides is designed to restore hair’s original luster by optimizing hydration levels, protecting against common environmental aggressors, and providing essential nutrients. Our tester, who struggles with thinning hair, used the oil for the recommended two to three times per week and noticed the most difference in the overall quality of her hair. “My hair appears softer, fuller, longer, and silkier than normal,” she said.

When new clients come to David in a panic due to sudden hair loss, he typically points them straight toward minoxidil—the main ingredient in this Rogaine foam designed for women. “It’s as aggressive an approach as you’re going to get over the counter,” he explains. This particular formula uses a five percent concentration of the growth-inducing ingredient, a dose high enough to be effective but low enough not to cause scalp irritation. Our tester appreciated the foam’s light, mousse texture during her six-times-per-week usage, the lack of scalp irritation, and was ultimately pleased to notice “an increased fullness in her hair.”

If your primary goal is to get big hair energy, look no further than this hair thickener from Viviscal. The wallet-friendly serum coats strands in a biotin- and keratin-infused formula to strengthen hair while majorly boosting density—leaving you with full, luscious strands, sans frizz or any greasy feeling. We appreciate that you can also apply the serum to wet and dry hair, making it an easy product to integrate practically anywhere in your haircare routine. The consistency, which our tester described as “thin, watery, and silky,” was something she particularly appreciated for fast absorption. Most of all, she enjoyed the immediate volume it provided. 

Long Story Short

Applying hair growth oil in the morning won’t get you princess-length strands by dinnertime, but with a little bit of patience, at least four weeks’ worth, you’ll experience a boost in length and thickness. At the very least, these oils will increase the overall health of your hair, providing nourishment, extra body, and shine. When using hair growth oils, “patience, diet, and consistency are key,” says Hingorani. “Results can vary based on your hair type, genetics, and the specific product you choose. A well-rounded approach that includes a healthy diet, staying hydrated, and managing stress can also enhance the effectiveness of hair growth treatments.”

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Allison Lax is an InStyle writer who just recently began using hair oil (and is starting to see results!) for her own stubbornly shoulder-length strands.