Fortero is a shampoo brand that’s used to stimulate hair growth. The brand claims that “The War Against Hair Loss Just Got Winnable” and that “carbonic acid shampoo stops men’s hair loss.”

But what is carbonic acid, and can it really reverse hair loss? Does Fortero Shampoo contain any other research-backed ingredients? Does it contain any harmful ingredients? And is Fortero Shampoo better or worse than popular hair growth shampoos like Mane Root Activator?

In this article we’ll answer all of these questions and more, as we analyze the ingredients in Fortero Shampoo to give our take on whether or not the shampoo is likely to be effective for hair growth, and whether or not it's healthy.

We’ll explain our issues with Fortero’s claims about carbonic acid, share our concerns about some of the brand’s marketing practices, and compare Fortero Shampoo to other popular hair growth products to pick our winners (and losers).

Key takeaways:

• Carbonic doesn't exist at room temperature for one second
• Premise behind company makes no sense
• We do not currently recommend Fortero Shampoo

Ingredient Analysis

The ingredients in Fortero Carbonic Acid Shampoo are shown below:

You will note that there is no listing of “carbonic acid,” the ingredient that the brand makes reference to throughout their marketing materials.

This is because carbonic acid only exists at room temperature for fractions of a second, according to UC Berkeley researchers, and is therefore not a suitable or logical ingredient for a shampoo formulation.

This shampoo does contain some ingredients with research backing for supporting hair growth.

Peppermint oil was shown in a clinical trial published in the Toxicological Research journal to cause hair growth when applied topically.

After four weeks, the animals receiving the topical peppermint oil treatment had 740% more hair follicles than the control group, and the treatment was found to be equally effective to minoxidil, which is the drug ingredient in hair growth products like Rogaine.

Rosmarinus officinalis (rosemary) extract was shown in a clinical trial published in the Phytotherapy Research journal to promote hair growth.

Serenoa serrulata extract has been shown to regenerate hair in clinical research, as we documented in our review of Routine Shampoo and Conditioner.

Caffeine was shown in a 2020 medical review to slow or even stop the progression of hair loss when applied topically.

Overall, we consider this to be a very well-formulated product for supporting hair growth.

It’s unfortunate that the brand makes such strange claims about carbonic acid, because otherwise, this is one of the best-formulated hair loss shampoos we’ve reviewed to date on Illuminate Health.

There are no inactive ingredients in this formulation that we consider to be unhealthy.

Highly Questionable Health Claims

Fortero claims that “a large reason that men deal with hair loss is that the hair roots are buried under layers of dirt and grime:” 

There is no citation for this claim and we have not come across any clinical evidence that male pattern baldness is caused by trapped dirt.

Male pattern baldness is a well-researched and well-understood phenomenon, and is primarily hormonal. 

A 2022 medical review describes how hair follicles miniaturize due to the influence of dihydrotestosterone (DHT), which is a hormone that testosterone converts into.

As documented in the above-linked study, pattern baldness “is a genetically predetermined disorder due to excessive response to androgens which affects up to 50% of males and females.”

In the “Help Center” section of their site, Fortero claims that “according to the research, our products must be used continuously to see the best results:” 

There is no citation for this claim.

Our question is: according to what research? Fortero Shampoo does not appear to have been tested in any clinical trials, so this sounds like a marketing claim disguised as a health claim to sell more products.

We recommend that consumers be wary about health claims made by brands that provide no proof to support such claims.

Is Fortero Lying About Media Appearances?

Update: Fortero appears to have removed these claims from their website since our article called out this information.

Fortero’s website claims that the brand has been “Featured In” four major media brands: GQ, Men’s Journal, GolfDigest and WIRED.

However, at the time of publishing this article, Fortero had never once been mentioned on the GQ website:

Fortero had never once been mentioned on the GolfDigest website:

Fortero had never once been mentioned on the WIRED website:

The brand had been mentioned once on Men’s Journal in a sponsored piece, meaning the brands involved, or their PR firms, paid the journal for this inclusion.

Perhaps Fortero was featured in the print rather than online versions of these media outlets, but we hope the brand clarifies this, because this seems like a red flag.

Fortero vs. Popular Hair Growth Shampoos

Here's how Fortero Shampoo compares to other popular hair growth shampoos in terms of formulation quality, in our opinion:

Adegen

This brand's topical serum contains an active ingredient which is FDA-approved for hair loss.

From a potential efficacy perspective, we give Adegen Topical Spolution the advantage over Fortero Shampoo

Winner: Adegen

Spartan Shampoo

Spartan Shampoo contains some research-backed active ingredients for hair loss, but also contains three inactive ingredients we consider unhealthy, including one which is clinically shown to be toxic to humans.

We consider Fortero Shampoo to be the healthier choice.

Winner: Fortero Shampoo

Mane Root Activator

Contains a synthetic preservative which is clinically shown to have hormone-disrupting effects.

Fortero Shampoo is the healthier choice.

Winner: Fortero Shampoo

Our Clean Hair Care Picks

Acure Vivacious Volume Shampoo is our top shampoo pick.

It contains argan oil which is clinically shown to help protect hair from damage.

Ritual HyaCera is our top hair growth supplement.

This supplement contains wheat oil extract, and a 2024 clinical trial reported that a wheat lipid complex had "a reducing effect on hair shedding and a stimulating effect on hair reappearance and growth."

Both of the products recommended in this section are free of ingredients we consider to be unhealthy.

Fortero Shampoo Pros and Cons

Pros:

• No unhealthy ingredients
• Effective formulation
• Should support natural hair growth
• Healthier than some competitors

Cons:

• Carbonic acid isn't stable at room temperature
• Highly questionable health claims
• Questionable media claims
  

Conclusion

Fortero Shampoo is a strange product.

It’s actually well-formulated, and we believe it may be effective for the natural treatment of hair loss, given that it contains several ingredients shown in clinical trials to be effective at stimulating hair growth.

However, the brand centers their marketing on a compound called carbonic acid which doesn’t appear to exist at room temperature.

Like the other carbonic acid shampoo brand we reviewed called Simfort Shampoo, Fortero fails to provide clinical evidence that carbonic acid is effective against hair loss, or that it exists at room temperature.

We don’t currently recommend this product due to the ingredient discrepancy and due to some of the strange marketing claims made by the brand, but Fortero Shampoo is free of any questionable or harmful additive ingredients which is a good thing.

We consider Fortero Shampoo to be a healthier option than hair loss shampoos Mane Root Activator and Spartan Shampoo, but less likely to be effective than Adegen.