Azelaic Acid: Does It Work for All Types of Hair Loss or Just DHT-Related Hair Loss?

Hair loss affects millions of people, and the causes are diverse. From hormonal factors to nutritional deficiencies and autoimmune disease, choosing a treatment depends on correctly identifying what is driving the loss.

In recent years, azelaic acid has been discussed as a possible option for hair loss, particularly the androgenetic kind linked to dihydrotestosterone (DHT), a hormone derived from testosterone.

However,

is its usefulness limited to hair loss driven by DHT? Or could it apply to other types of alopecia?

This article sets out what the published evidence actually shows, how azelaic acid is understood to work, and where the claims made for it run ahead of the data.

What is azelaic acid and how does it work on the scalp?

Azelaic acid is a compound found naturally in cereals such as wheat, rye and barley. It has been used mainly for acne and rosacea, where it reduces bacterial growth and skin inflammation. The interest in hair comes from reports that it inhibits 5-alpha reductase, the enzyme that converts testosterone into DHT.

DHT is an androgen that, in genetically predisposed individuals, shortens the hair growth cycle and progressively weakens hair follicles. The evidence that azelaic acid inhibits 5-alpha reductase is laboratory evidence: Stamatiadis and colleagues (British Journal of Dermatology, 1988) measured the enzyme in human skin in vitro and found azelaic acid inhibited it, and closed by noting that the finding would need to be confirmed in vivo. A separate laboratory study, Amirfakhryan and colleagues (Avicenna Journal of Phytomedicine, 2020), worked with mouse whisker follicle cells and reported that azelaic acid raised catalase activity in bulge cells and increased Gli1/Gli2 expression, and that minoxidil, alone or combined with azelaic acid, increased Sonic hedgehog protein — again in cultured cells and organ culture, not in people. Whether either effect translates into scalp DHT reduction in a living person has not been demonstrated.

Scalp Inflammation: A Warning Sign of Hair Loss

Inflammation is the body's natural response to injury, infection or immune imbalance. When inflammation becomes chronic, it can interfere with normal hair follicle function and contribute to hair loss. On the scalp, inflammation is not always obvious, but it can show up in several ways, both visible and felt.

What does scalp inflammation feel like?

People with scalp inflammation often describe burning, stinging or tenderness. There may be a feeling of tightness, as if the skin were tighter than usual. In some cases there is persistent itching that does not settle with normal washing and can worsen with certain hair products.

What does scalp inflammation look like?

Visually, scalp inflammation can appear as redness, scaling and sometimes small pustules or crusts. The skin may look shinier or irritated. In people with seborrhoeic dermatitis or scalp psoriasis, it may present as white or yellowish scaly plaques attached to the skin.

Why is it important to reduce inflammation in hair loss?

Where inflammation persistently affects follicles, dermatology texts describe a disruption to the growth cycle: the anagen (growth) phase can shorten and more hairs can enter the telogen (shedding) phase early, accelerating thinning. Chronic inflammation in scarring conditions can also lead to fibrosis, after which regrowth is not possible in the affected area. Anyone with a red, scaling, painful or scarring scalp should be seen by a doctor rather than self-treating, because scarring alopecias need to be diagnosed and treated early.

Azelaic acid's anti-inflammatory action is well documented in acne and rosacea. It is reasonable to say that it calms inflamed skin. It does not follow that it treats the alopecias in which inflammation plays a part — no published trial has tested azelaic acid for alopecia areata, telogen effluvium, or hair loss associated with seborrhoeic dermatitis, so any benefit there is speculation rather than a finding.

Scientific Evidence on Azelaic Acid and Androgenetic Alopecia

The one randomised human trial that can be located is Thanomkitti and colleagues (Siriraj Medical Journal, 2023). Twenty-six women with female pattern hair loss (Ludwig grade I or II) were randomly assigned to 5% azelaic acid solution or 2% minoxidil solution, applied twice daily for six months, with hair density and hair shaft diameter measured at baseline and at 2, 4 and 6 months. Both groups improved significantly from their own baseline, and there was no statistically significant difference between the two groups at any visit. Itching was the main side effect in both arms and was described as mild. The authors conclude that 5% azelaic acid "might be an effective treatment for FPHL, comparable with 2% minoxidil", and suggest it as an alternative where minoxidil is not an option.

That trial is worth reading carefully before it is over-read. Twenty-six patients is a very small study, there was no placebo or untreated arm, so the improvement from baseline in both groups cannot be separated from the effect of measurement and time, and the comparator was 2% minoxidil in women rather than the 5% strength. "No significant difference between two small groups" is not the same as "equally effective". It is a promising first result that has not been replicated in a larger trial.

Beyond that, the evidence is laboratory work: the in-vitro 5-alpha reductase inhibition in human skin reported by Stamatiadis and colleagues in 1988, and the mouse follicle cell work of Amirfakhryan and colleagues in 2020. Neither shows a clinical effect in people.

Figures that circulate online for azelaic acid — a named journal and year, a participant count, a percentage of extra regrowth — should be checked against the journal itself before being repeated. Several such citations do not lead to a real paper.

What about other types of alopecia?

Azelaic acid's anti-inflammatory action makes it a plausible candidate for hair loss in which inflammation plays a part. Plausible is as far as the evidence goes.

Alopecia areata: an autoimmune condition in which the immune system attacks hair follicles, producing sudden patchy loss. No published trial tests azelaic acid in alopecia areata. Treatment for alopecia areata is a medical matter — topical and intralesional corticosteroids, contact immunotherapy, and for extensive disease the approved JAK inhibitors baricitinib, ritlecitinib and deuruxolitinib. These are prescription tablets whose US labels carry a boxed warning for serious infections, death, cancer, major cardiovascular events and blood clots (Olumiant, Litfulo and Leqselvi prescribing information on DailyMed), so they are used only under specialist supervision. An over-the-counter acne topical is not an alternative to seeing a dermatologist for this condition, and using one instead of treatment can cost time in a condition where early treatment matters.

Telogen effluvium: this diffuse shedding is usually triggered by stress, illness, surgery, a medication, or hormonal change, and it is normally handled by identifying and removing the trigger. There are no studies of azelaic acid in telogen effluvium, and there is no reason to expect a topical anti-inflammatory to address a systemic trigger.

Seborrhoeic dermatitis and hair loss: chronic scalp inflammation from seborrhoeic dermatitis can be uncomfortable and is associated with shedding. Azelaic acid is an established anti-inflammatory in other skin conditions, and treating seborrhoeic dermatitis properly is worthwhile in itself, but no study has shown that treating it with azelaic acid reduces hair loss. Seborrhoeic dermatitis has its own first-line treatments (antifungal shampoos, topical steroids) that a doctor or pharmacist can advise on.

User Experiences

Azelaic acid is discussed in the hair loss community mainly for its supposed DHT-blocking properties, and opinions on it vary widely. Many users report that they use it for androgenetic alopecia (AGA) on the basis of 5-alpha reductase inhibition. There is little agreement about whether it does anything for other forms of hair loss such as telogen effluvium or alopecia areata.

One user described adding azelaic acid to a regimen that already included finasteride and minoxidil, hoping to reinforce the DHT-blocking effect. They reported less scalp oiliness and irritation, but were unsure whether the azelaic acid itself contributed to any regrowth. Another said it improved scalp condition and reduced inflammation, which they thought might indirectly help growth, while noting they saw no substantial new hair from using it alone.

Several users argue that even if azelaic acid contributes to a healthier scalp, any DHT-blocking effect is likely mild next to finasteride or dutasteride. Some who used it in a combined topical with minoxidil said their scalp felt less inflamed, while stressing it was unlikely to work as a standalone route to significant regrowth.

Others are sceptical, saying azelaic acid's role is overstated. One commenter pointed to the fact that the 5-alpha reductase evidence is laboratory work, so how much it affects hair loss in practice is unclear. Another noted that if azelaic acid were a strong DHT blocker, it would be recommended far more widely in mainstream dermatology.

Community feedback overall suggests azelaic acid may have modest benefit in androgenetic alopecia, that its effect appears limited when used alone, and that it does not address every type of hair loss. Most members treat it as a supplementary product rather than a primary treatment.

A note on seeing a doctor

Azelaic acid at prescription strengths (15% and 20%) is a medicine, and the conditions discussed here — alopecia areata, telogen effluvium, seborrhoeic dermatitis, scarring alopecia — need a diagnosis before they can be treated sensibly. Talk to a doctor, dermatologist or pharmacist before starting, stopping or combining azelaic acid, and see a doctor rather than self-treating if your hair loss is patchy, sudden, painful, or accompanied by a red, scaling or scarring scalp.

References

Stamatiadis, D., Bulteau-Portois, M. C., & Mowszowicz, I. (1988). Inhibition of 5 alpha-reductase activity in human skin by zinc and azelaic acid. British Journal of Dermatology, 119(5), 627–632. https://pubmed.ncbi.nlm.nih.gov/3207614/

Amirfakhryan, E., Davarnia, B., Jeddi, F., & Najafzadeh, N. (2020). Azelaic acid stimulates catalase activation and promotes hair growth through upregulation of Gli1 and Gli2 mRNA and Shh protein. Avicenna Journal of Phytomedicine, 10(5), 460–471. https://pubmed.ncbi.nlm.nih.gov/32995324/

Thanomkitti, K., Pruksaeakanan, C., Subchookul, C., Charoenpipatsin, N., Triwongwaranat, D., Varothai, S., Thuangtong, R., & Chumnumrat, T. (2023). Efficacy and Safety of Topical 5% Azelaic Acid Solution Versus 2% Minoxidil Solution in the Treatment of Female Pattern Hair Loss. Siriraj Medical Journal, 75(12), 887–893. https://he02.tci-thaijo.org/index.php/sirirajmedj/article/view/266001

Hosking, A. M., Juhasz, M., & Atanaskova Mesinkovska, N. (2019). Complementary and Alternative Treatments for Alopecia: A Comprehensive Review. Skin Appendage Disorders, 5(2), 72–89. https://pubmed.ncbi.nlm.nih.gov/30815439/