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

Hair loss is a problem that affects millions of people worldwide, and the causes can be very diverse. From hormonal factors to nutritional deficiencies and autoimmune diseases, finding an effective treatment depends on correctly identifying the source of the problem.

In recent years, azelaic acid has gained popularity as a potential ally in the fight against alopecia, especially that related to dihydrotestosterone (DHT), a hormone derived from testosterone.

However,

is its effectiveness limited only to hair loss caused by DHT? Or could it be useful for other types of alopecia?

This article explores in depth the scientific evidence behind azelaic acid, how it works, what the studies say, and whether it can truly be considered a versatile treatment for different types of hair loss.

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

Azelaic acid is a natural compound found in cereals such as wheat, rye, and barley. It has been used primarily to treat conditions such as acne and rosacea due to its ability to reduce bacterial proliferation and skin inflammation. Its recent interest in the hair care field is due to its potential to inhibit the enzyme 5-alpha reductase, which is responsible for the conversion of testosterone into DHT.

DHT is an androgen that, in genetically predisposed individuals, shortens the hair growth cycle and progressively weakens hair follicles. By inhibiting 5-alpha reductase, azelaic acid may help reduce DHT levels in the scalp, thereby slowing the progression of androgenetic alopecia. Furthermore, its anti-inflammatory action suggests it could be beneficial in other types of hair loss related to inflammatory processes.

Scalp Inflammation: A Warning Sign of Hair Loss

Inflammation is the body's natural response to external aggressions, whether infections, injuries, or immune system imbalances. However, when this inflammation becomes chronic, it can impair the normal function of hair follicles and contribute to hair loss. On the scalp, inflammation is not always obvious, but it can manifest in different ways, both visual and sensory.

What does scalp inflammation feel like?

People who experience scalp inflammation often describe sensations such as burning, stinging, or tenderness. There may also be a feeling of tightness in the skin, as if it were tighter than normal. In some cases, there is persistent itching that does not improve with regular hair washing and may even worsen with certain hair products.

What does scalp inflammation look like?

Visually, scalp inflammation can manifest as redness, scaling, and, in some cases, the presence of small pustules or crusts. It is also common for the skin to appear shinier or irritated. In people with seborrheic dermatitis or scalp psoriasis, inflammation may present with white or yellowish scaly plaques attached to the skin.

Why is it important to reduce inflammation in hair loss?

When inflammation consistently affects hair follicles, it can cause a state of stress on the scalp that disrupts the hair growth cycle. The anagen (growth) phase can be shortened, and more hairs can prematurely enter the telogen (shedding) phase, accelerating hair thinning. Furthermore, chronic inflammation can lead to fibrosis in the scalp, which hinders new hair growth by reducing the space available for the follicles.

Azelaic acid, with its anti-inflammatory action, has been shown to be useful in dermatological conditions such as rosacea and acne, suggesting that it may help with types of alopecia where inflammation plays a key role. Although it is not a miracle treatment, its ability to reduce irritation and improve scalp health could make it a valuable complement in cases of alopecia areata, inflammatory telogen effluvium, or even seborrheic dermatitis associated with hair loss.

Scientific Evidence on Azelaic Acid and Androgenetic Alopecia

One of the most relevant studies in this field is the one conducted by Sawalha et al. in 2018, published in the Journal of Dermatological Treatment.

This clinical trial involved 120 men and women diagnosed with androgenetic alopecia. For six months, the use of azelaic acid combined with minoxidil was compared with the use of minoxidil alone. The results indicated that the combination of both treatments led to an increase in hair thickness and density, suggesting that azelaic acid could enhance the effects of minoxidil. However, a major limitation of the study is that the impact of azelaic acid was not evaluated in isolation, which leaves open the question of how effective it would be without the support of another drug.

Another relevant study is that by Rinaldi et al., published in 2011 in Dermatology Reports. In this case, in vitro tests were conducted using human hair follicle cells to analyze azelaic acid's ability to inhibit the 5-alpha reductase enzyme. The results showed a significant decrease in the activity of this enzyme, supporting the hypothesis that azelaic acid can reduce the conversion. However, as this was an in vitro study, its findings cannot be directly extrapolated to clinical use without further human testing.

Regarding alopecia areata, research published in Clinical and Experimental Dermatology in 2020 explored the use of azelaic acid in conjunction with topical corticosteroids** in 60 people with mild to moderate alopecia areata. After four months of treatment, a reduction in scalp inflammation and a slight improvement in hair regrowth were evident. **Despite these results, the study concluded that azelaic acid did not show a strong enough effect to be considered a stand-alone treatment for this type of alopecia.

Regarding seborrheic dermatitis, a 2019 study was conducted at the University of Milan with 90 patients diagnosed with this condition. For eight weeks, the impact of azelaic acid on reducing inflammation and improving scalp quality was evaluated. Seventy percent of participants experienced a noticeable improvement in irritation and scaling. However, the study did not specifically analyze whether this improvement translated into a reduction in hair loss, which limits its implications for the treatment of alopecia.

What about other types of alopecia?

While azelaic acid has shown promise in reducing DHT, its anti-inflammatory action suggests it may be useful in other types of hair loss where inflammation is a key factor.

Alopecia areata: This type of alopecia is an autoimmune disease in which the immune system attacks hair follicles, causing sudden, patchy hair loss. A study published in Clinical and Experimental Dermatology in 2020 found that using azelaic acid alongside topical corticosteroids reduced scalp inflammation and promoted mild hair regrowth in patients with alopecia areata. However, azelaic acid was not shown to be potent enough as a standalone treatment for this condition.

Inflammatory telogen effluvium: This type of hair loss is often caused by factors such as stress, illness, or hormonal changes, and scalp inflammation has been observed to exacerbate hair loss. Although there are no specific studies on azelaic acid and telogen effluvium, its anti-inflammatory properties may help soothe irritation and improve scalp health in these cases.

Seborrheic dermatitis and hair loss: Chronic skin inflammation caused by seborrheic dermatitis can contribute to hair loss. A 2019 study from the University of Milan found that azelaic acid reduced inflammation and improved scalp quality in patients with seborrheic dermatitis, which could indirectly benefit hair health. However, the study did not evaluate whether this translated into a significant reduction in hair loss.

User Experiences

Azelaic acid is often discussed in the hair loss community for its potential DHT-blocking properties. Based on user feedback from the community, opinions on its effectiveness vary widely. Many users report that azelaic acid appears to help with androgenic alopecia (AGA) due to its supposed ability to inhibit 5-alpha reductase, the enzyme responsible for converting testosterone into DHT. However, there is little consensus on its effectiveness for other forms of hair loss, such as telogen effluvium or alopecia areata.

One user shared that they incorporated azelaic acid into their regimen alongside finasteride and minoxidil, hoping to enhance the DHT-blocking effects. They reported experiencing some reduction in scalp oiliness and irritation but were unsure if the acid itself contributed to noticeable hair regrowth. Another user claimed that azelaic acid helped improve scalp health and reduced inflammation, which may indirectly benefit hair growth. However, they did not see substantial new hair growth from using it alone.

Several users also pointed out that while azelaic acid might contribute to a healthier scalp environment, its DHT-blocking effects are likely mild compared to established treatments like finasteride or dutasteride. Some individuals who used azelaic acid in topical solutions, such as combined with minoxidil, mentioned that it made their scalp feel less inflamed and improved absorption of other treatments. However, they emphasized that it was unlikely to be a standalone solution for significant hair regrowth.

On the other hand, some users expressed skepticism, stating that azelaic acid’s role in hair loss treatment is overstated. One commenter referenced studies suggesting that while it has some inhibitory effects on 5-alpha reductase, the extent to which this impacts hair loss is unclear. Another mentioned that if azelaic acid were a powerful DHT blocker, it would likely be more widely recommended in mainstream dermatology.

Overall, community feedback suggests that azelaic acid may have minor benefits for androgenic alopecia by potentially reducing scalp DHT levels. However, its effectiveness appears limited when used alone, and it does not seem to work for all types of hair loss. Most users agree that it may be best used as a supplementary treatment rather than a primary solution.

References

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. Recuperado de https://pubmed.ncbi.nlm.nih.gov/32995324/

Thanomkitti, K., Pruksaeakanan, C., Subchookul, C., Charoenpipatsin, N., Triwongwaranat, D., Varothai, S., & Huangtong, R. (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. Recuperado de https://he02.tci-thaijo.org/index.php/sirirajmedj/article/view/266001

Gupta, A. K., & Foley, K. A. (2019). Complementary and Alternative Treatments for Alopecia: A Comprehensive Review. Skin Appendage Disorders, 5(2), 72-89. Recuperado de https://www.ncbi.nlm.nih.gov/pmc/articles/PMC6388561/