Can centella improve scalp blood flow and thicken hair? What the evidence says

Have you ever wondered why your hair doesn't grow as thick as it used to? Poor scalp blood flow is one of the explanations that gets offered, and centella asiatica is one of the ingredients most often suggested for it. Here is what that idea rests on, and how thin the evidence actually is.

Many people notice that, as they age, their hair begins to thin, grow more slowly, or fall out in specific areas of the scalp. This happens in both men and women. Reduced blood flow to the scalp is one factor that has drawn research attention, on the reasoning that follicles starved of oxygen and nutrients cannot sustain strong, thick hair. It is important to say at the outset that this is a proposed contributing factor, not an established cause of pattern hair loss.

What does circulation have to do with hair growth?

Each hair follicle is served by a capillary network. The standard reasoning is that if that supply is reduced, the follicle spends longer in its resting phase (telogen), and the hair it does produce is finer. Good perfusion is also said to help clear waste products and free radicals, and oxidative stress has been linked to hair loss in laboratory work.

That reasoning is widely repeated, but it should not be mistaken for a settled explanation of androgenetic alopecia. Reduced blood flow has been measured in balding scalp, but measuring less flow in an area that has already lost hair does not establish that the reduced flow caused the loss — thinner, miniaturised follicles need less blood. The direction of cause is genuinely unresolved. Whether increasing scalp blood flow grows hair has not been shown in a controlled human trial.

When the Problem Is Hormonal: DHT and Circulation

One of the main causes of hair loss in men and women is androgenetic alopecia, driven by dihydrotestosterone (DHT), a hormone derived from testosterone. DHT binds to receptors in genetically susceptible follicles and miniaturises them, so each new hair is finer than the last, until the follicle stops producing visible hair.

It is sometimes claimed that DHT also reduces scalp microcirculation. No published study demonstrates this, and it should be treated as speculation rather than an observed effect.

Even on the most optimistic reading, improving blood flow would not reverse hormonal miniaturisation. At best it is proposed as a supporting condition, and that proposal has not been tested.

What if the cause is an inflammatory scalp disease?

Other conditions, such as alopecia areata or seborrheic dermatitis, involve inflammation of the scalp. In alopecia areata, an autoimmune condition, the immune system attacks the hair follicles, and the resulting local inflammation affects the follicle and the tissue around it.

Metabolic disease can affect small blood vessels generally. Sustained high blood sugar in type 2 diabetes damages microvasculature throughout the body, and the scalp is not exempt, though the effect of this on hair specifically has not been quantified.

The practical point is that hair loss has no single cause, and improving circulation will not solve it. If it helps at all, it is as a supporting factor alongside treatments that have been tested — and calming an inflamed scalp is a more defensible reason to use a soothing ingredient than any claim about growing hair.

What is actually known about centella and hair?

The evidence for centella asiatica and hair is thin and preclinical. Choi and colleagues (2017), in Bioscience, Biotechnology, and Biochemistry, reported that a titrated extract of Centella asiatica increased the hair-inductive property of human dermal papilla cells grown as three-dimensional spheroids, through inhibition of the STAT signalling pathway. That is a cell-culture study. It involved no people, no scalps and no measurement of hair growth, and results in dermal papilla cells routinely fail to reproduce in humans.

Centella extracts have a longer research history for blood vessels elsewhere in the body, mostly in chronic venous insufficiency of the legs. No published study has measured scalp blood flow in people using centella, and no clinical trial has tested centella for hair loss. Anything stronger than "it is an interesting ingredient with soothing properties and no hair evidence yet" is going beyond what exists.

Centella products: what is sold, and what the brands claim

Centella is widely sold in Korean-style skincare — ampoules, essences and creams — and some people apply these to the scalp. It is worth being clear about what these products are: they are formulated and tested for facial skin, and marketed for soothing, hydration and skin barrier repair. None of them is tested, approved or marketed as a hair loss treatment, and the claims below are the manufacturers' own advertising, not findings.

Typical products are centella facial ampoules, essences and serums, often combined with hyaluronic acid. Brands market them for soothing and hydrating sensitive or irritated skin and for supporting the skin barrier, and a few say they can also be used on the scalp. Tressless does not endorse any of these products and has no affiliate relationship with their sellers.

These are cosmetics. They may make an irritated scalp feel more comfortable, which is a reasonable thing to want. They do not replace medical treatment for hair loss, and no evidence connects any of them to hair growth. Patch-test anything new, and be aware that a product formulated for the face may contain fragrance or actives that irritate a scalp that is already inflamed or that has recently had a procedure.

User Experiences

Several community members on Tressless have discussed Centella asiatica (also known as Gotu Kola) in the context of scalp health. The sentiment is cautious, with users describing it as a supportive ingredient alongside other treatments rather than a treatment in itself.

One user in a discussion about hair transplant complications mentioned using a combination of La Roche-Posay B5 cream, thermal water, and Centella asiatica to soothe inflammation and support scalp healing after what appeared to be severe shock loss in the donor area. This individual was also using oral minoxidil and dutasteride, both prescription medicines. Others in the thread said centella-based creams can reduce inflammation and support the skin barrier.

In a separate conversation about experimental treatments, another user mentioned Centella asiatica-derived exosomes as part of a broader discussion of cutting-edge therapies. Exosome products in general were viewed sceptically in that thread because of questions about their stability and effectiveness. Exosome treatments are unapproved and their long-term safety is unknown.

Centella asiatica appears to be used by some community members as a soothing agent in post-procedure or general scalp care rather than as a growth treatment. No one reported meaningful regrowth from centella alone.

Is Centella worth trying?

There is no miracle treatment for hair loss, and centella is not a candidate for one. The published work is a cell-culture study plus a general reputation as a soothing, barrier-supporting ingredient. If your scalp is inflamed or irritated, a centella product may make it more comfortable — that is the honest case for it. There is no evidence that it improves scalp circulation or grows hair.

Cosmetic centella products are generally well tolerated on facial skin, but "natural" does not mean without risk: contact dermatitis and allergic reactions to plant extracts and to the fragrances and preservatives around them do occur, and no product has been tested for long-term use on the scalp. Patch-test first.

As always, before starting any new routine — even one with natural ingredients — it's advisable to consult a dermatologist or pharmacist, especially if your hair loss is severe or sudden, if your scalp is inflamed or broken, or if you are already using a prescribed treatment. Sudden or patchy hair loss can indicate a condition that needs diagnosis rather than a serum.

References

Choi, Y. M., An, S., Lee, J., et al. (2017). Titrated extract of Centella asiatica increases hair inductive property through inhibition of STAT signaling pathway in three-dimensional spheroid cultured human dermal papilla cells. Bioscience, Biotechnology, and Biochemistry, 81(12), 2323–2329. PMID 29032741. https://pubmed.ncbi.nlm.nih.gov/29032741/