A Dermatologist's Perspective on Acceleroot Hair Growth Oil

Jakob Nielsen, MD, PhD
Dermatologist, medical researcher, and medical expert for Norvivo AS

How I Got Into This

Dermatologists are naturally skeptical of claims about hair growth. We see a steady stream of products, oils, serums, dietary supplements, and devices that promise regrowth, often based on marketing and little else. So when the team behind Acceleroot® contacted me, my initial reaction was the same as always: skepticism combined with a willingness to let the evidence speak for itself.

What got me involved wasn’t the product itself, but the way Norvivo structured the conversation. They weren’t looking for an uncritical endorsement. They wanted the product to be thoroughly tested, and they wanted someone with professional authority and the freedom to be critical to be in charge of this. They were prepared to publish the findings regardless of the results. That attitude—the desire to understand and be certain, rather than just to sell—is unusual in the cosmetics market, and that’s what made me say yes.

I joined the project after the study had been designed and recruitment had begun. The Norvivo team did not have a background in clinical research and had relied heavily on the contracted research organization.

My role was to provide experienced clinical and scientific oversight to ensure that the study was conducted as planned, that data were collected correctly, and that any challenges were identified and addressed along the way.

Clinical trials are complex and involve real people, so unforeseen challenges are not uncommon—not even in this trial. What matters most is how such issues are identified, addressed, and documented. That is what determines whether the results are reliable.

The complete study results were published in EuroCosmetic1 in 2025. What follows here is a brief summary of the main findings.

The study, and how it was evaluated

Thirty participants with mild to moderate hair thinning completed the 20-week study, during which they applied the oil every other day. The effect was assessed from three different perspectives—a deliberate choice, since hair loss is not a single factor that can be measured in just one way.

The first was objective imaging. HairMetrix is a standardized system that photographs a defined area of the scalp and counts individual hairs per square centimeter with automated precision. The second was an examiner’s assessment, in which a trained clinician evaluated visible changes in hair density and perceived scalp health at each visit. The third was self-reported data from the participants, including hair shedding, perceived density, scalp comfort, and satisfaction.

One detail from the study is worth highlighting, because it also reflects the participants’ actual experience. Six participants were mistakenly included even though they had more pronounced hair thinning than the inclusion criteria allowed. When this was discovered, they were informed and offered the opportunity to withdraw, but all chose to continue.

Their results were analyzed along with the rest of the group and did not differ in any meaningful way from the others. If anything, that’s reassuring. The oil appeared to be effective across a slightly broader spectrum of hair thinning than the protocol was originally designed to investigate.

What the results showed

By week 20, the number of hairs per square centimeter—that is, hair density—had increased by an average of 17.9 hairs, which corresponds to a 14.7 percent increase from the start of the study. This change was statistically significant, meaning it was unlikely to be due to chance alone. Hair coverage—a measure of the proportion of the scalp’s surface covered by hair—improved by about 20 percent.

Average figures can mask variation among participants, because interventions rarely have the same effect on everyone. That is why it is also useful to look at the range of results. Approximately 63 percent of participants showed a clear positive response, and in this group, the average increase was 38.9 additional hairs per square centimeter—that is, nearly 28 percent. The remaining participants showed little or no measurable change. This is a realistic and credible outcome in a clinical study. Most saw an effect, but not all.

The assessments conducted by the researchers tracked changes in the overall visual appearance of the hair on the scalp. 90 percent of the participants showed visible improvement in hair density—that is, how full the hair appeared—by week 20, and 100 percent showed improved appearance of the hair strands and better scalp health.

The questionnaires completed by the participants showed that 70 percent felt their hair looked thicker, 80 percent reported reduced hair loss, 87 percent reported improved scalp comfort, and 77 percent said they would recommend the product.

In all clinical studies, it is crucial to assess whether a treatment is safe to use. In this study, participants reported no side effects from using the hair oil throughout the study period. This is a highly relevant finding, because adverse effects often limit the long-term use of treatments for hair loss.

The Decline in Week 4, and Why It Might Be Important

One pattern in the data requires some explanation, because, taken in isolation, it might look like a warning signal.

The number of hairs decreased slightly by week 4 before increasing noticeably by weeks 12 and 20. Hair does not grow in a straight line. Each hair follicle goes through phases—growth, transition, and rest—and when this cycle is stimulated, older resting hairs often fall out before new growth becomes visible.

This pattern of a temporary increase in hair shedding during the first few weeks of treatment is also known to occur with medical treatments for hair loss, and is generally interpreted to mean that the hair follicle is being pushed back into an active growth phase rather than remaining inactive.

The pattern showing a decline by week 4 is therefore consistent with this biological process. It does not prove that the hair oil works in the same way as medical treatments, but it is important in practice for one reason. A person who notices slightly increased hair shedding around week 4 and stops using the product may, in reality, give up just as the cycle is about to change.

The ingredients, and why no single ingredient alone explains the result

When it comes to botanical products, the instinct is often to look for a single active ingredient and evaluate it in isolation. For this formulation, however, such an approach misses the point, because it is likely the combination of all the ingredients that makes the difference.

Several of the oils—such as rosemary, pumpkin seed, and amla—have been the subject of published research suggesting they affect the hormonal signaling pathway that drives pattern hair loss. Others help by supporting blood circulation in the scalp, including peppermint and rosemary. A third group, including sesame, avocado, and less common botanical ingredients such as ungurahua, mamey sapote, kakadu plum, harakeke, and caiaue, appears to support the scalp’s environment itself, including its barrier function, low-grade inflammation, and the conditions that allow hair follicles to function optimally. Vitamins, minerals, and omega fatty acids support follicular metabolism and hair structure.

No single mechanism is likely to explain the results on its own. The most plausible interpretation is that these effects work together, gently and over time, in a way that no single ingredient could achieve on its own. This is also why the study’s 20-week duration is important. Meaningful changes in hair biology do not occur in four or six weeks, and a shorter study would most likely have overlooked the effect.

Limitations

This study was conducted without a control group; that is, all participants used the product, and there was no separate group that received a placebo or no treatment. Therefore, we cannot say with complete certainty how much of the improvement, if any, would have occurred on its own over time. Hair density can fluctuate naturally, and without a direct comparison, this remains an open question, even though this type of hair thinning does not typically improve spontaneously. This is the most significant scientific limitation of the study, and it should be clearly acknowledged when the results are interpreted and presented.

Within these parameters, however, the study still provides clear and meaningful clinical results, supported by both objective measurements and the participants’ own experiences—which is unusual for this type of product. This means that the evidence clearly goes beyond the anecdotal level, although a randomized, placebo-controlled study remains the necessary next step.

What this means

Acceleroot® is not a substitute for medical treatment. What it does appear to be, however, is something the field has long lacked: a non-pharmaceutical alternative backed by actual clinical evaluation, good tolerability, and measurable improvements in both hair density and scalp condition, documented through hair counts, clinical assessment, and patient experience.

For someone with thinning hair who wants to try something before, or instead of, medication, this is a reliable place to start.

I went into this project as a skeptic, and I still am—that’s just the nature of clinical research. What made me want to collaborate with Norvivo in the first place was their willingness to thoroughly test the product and let the data speak for itself. What changed my mind was that the data provided a consistent signal, and that’s really all I can reasonably expect from a clinical study.

Reference

1) Nielsen, J. A. "A 20-Week Clinical Trial Evaluating the Effects of Acceleroot® Hair Growth Oil on Hair Growth and Scalp Health." EuroCosmetics. April 2025;33(4):18-22.