What happens if I mix azelaic acid with minoxidil or anti-hair loss shampoos?

Hair loss is a problem that affects millions of people around the world, with androgenetic alopecia being one of the most common causes. This has led to a constant search for effective treatments to mitigate or even reverse this process. Among the most popular options are minoxidil and azelaic acid, two compounds used to promote hair growth.

However, many people wonder if it is safe or beneficial to combine them, or even if these treatments can be complemented with anti-hair loss shampoos. Throughout this article, we will explore the mechanisms of action of these products, the studies that support their effectiveness, and the possible interactions between them.

The context behind the search for combination solutions for hair loss

Hair loss can be a difficult condition to treat due to its multiple causes, which include genetic, hormonal, and environmental factors. Specifically, androgenetic alopecia is one of the most common forms of hair loss in men and women. It is characterized by a genetic predisposition to hair follicle miniaturization due to the action of dihydrotestosterone (DHT), a hormone derived from testosterone.

FDA-approved minoxidil is one of the most commonly used topical treatments for this condition. Its mechanism of action is not entirely clear, but proposed mechanisms include increased blood flow around the follicle and a longer anagen (growth) phase of the hair cycle. Azelaic acid, although originally used to treat dermatological conditions such as acne and rosacea, has gained popularity in the fight against alopecia due to its anti-inflammatory properties and because it inhibited the enzyme 5-alpha reductase, which converts testosterone to DHT, in laboratory tests.

Minoxidil: An Approved Treatment for Hair Loss

Minoxidil is a compound applied directly to the scalp and is FDA-approved for the treatment of androgenetic alopecia. Its exact mechanisms of action are not fully understood; a 2004 review by Messenger and Rundegren describes the proposed mechanisms, including effects on the hair growth cycle and on blood flow around the follicle. However, some users experience side effects such as scalp irritation, itching, and even a temporary increase in hair loss when starting treatment.

Minoxidil is one of two medicines the US FDA has approved for pattern hair loss (the other is finasteride), and it is widely available without a prescription. A pharmacist or doctor can advise on side effects and on whether it suits you.

Azelaic Acid: An Emerging Ally in the Fight Against Alopecia

Azelaic acid is an organic compound that, in addition to being used in the treatment of acne and rosacea, is gaining attention for its potential effects on alopecia. In laboratory work, this acid inhibited the enzyme 5-alpha reductase, which converts testosterone into DHT, a hormone that plays a key role in androgenetic alopecia. Inhibiting this enzyme could, in theory, help reduce DHT concentrations in the scalp and therefore prevent hair loss related to the action of this hormonal compound.

In a 1988 laboratory study, azelaic acid inhibited 5-alpha reductase in human skin samples (Stamatiadis et al., British Journal of Dermatology, 1988). This has not been confirmed in the living scalp. The only hair-loss trial of azelaic acid compared 5% azelaic acid with 2% minoxidil in 26 women with female pattern hair loss and found no significant difference between the groups, with no placebo group (Thanomkitti et al., Siriraj Medical Journal, 2023). It was too small to show the two work equally well.

Azelaic acid is generally well tolerated, with limited side effects. However, some people may experience temporary skin redness, burning, or stinging, especially at the beginning of treatment.

What happens if we combine azelaic acid with minoxidil?

It has been suggested that this combination could work better than either treatment alone, but that idea has not been tested.

The combination of minoxidil and azelaic acid has generated some interest because the two treatments target different mechanisms of hair loss. Minoxidil acts on the hair growth cycle, while azelaic acid inhibited DHT production in laboratory work only.

No published trial has tested azelaic acid combined with minoxidil. The only hair-loss trial of azelaic acid compared it with 2% minoxidil in 26 women and found no significant difference, in a study too small to show equivalence and with no placebo group (Thanomkitti et al., Siriraj Medical Journal, 2023). Whether adding one to the other changes the result is unknown.

Anti-hair loss shampoos: Can they improve results when combined with minoxidil or azelaic acid?

Anti-hair loss shampoos, which often contain ingredients such as caffeine, ketoconazole, and biotin, have also become popular as complementary supplements in the treatment of hair loss.

Ingredient lists differ between brands and change over time, so check the label of the specific product.

Caffeine has been suggested to stimulate hair follicles, but evidence in people is limited. A small 1998 study in men with pattern hair loss reported that 2% ketoconazole shampoo improved hair density and the proportion of growing hairs almost as much as a 2% minoxidil regimen; the authors said the result needed a larger controlled study (Piérard-Franchimont et al., Dermatology, 1998). It did not measure DHT. However, there is no conclusive evidence as to whether these shampoos interact significantly with azelaic acid or minoxidil.

Some products combine minoxidil and ketoconazole in one formulation. There is no published data showing that adding azelaic acid to such products improves results.

User Experiences

Mixing azelaic acid with minoxidil or hair loss shampoos has generated mixed reactions from the community, with some users reporting potential benefits while others experience irritation or reduced effectiveness.

Some users have mixed azelaic acid products into their minoxidil solution. This is not advised: adding anything to a minoxidil solution changes how much drug reaches the scalp in ways nobody has tested. If you use both, apply them separately and ask a pharmacist first. Others, however, caution that azelaic acid can be irritating, particularly when combined with alcohol-based minoxidil solutions, leading to dryness, redness, or flaking.

A few users also experimented with adding azelaic acid to hair loss shampoos, such as ketoconazole-based formulas. Some reported that this combination helped with scalp inflammation and dandruff, possibly due to azelaic acid’s antimicrobial properties. However, others warned that it could make the shampoo too harsh, leading to excessive scalp dryness. One commenter noted that using azelaic acid alongside ketoconazole shampoo made their scalp feel tight and uncomfortable, causing them to discontinue use.

There are also concerns about potential interference with minoxidil absorption. Some users speculate that azelaic acid might alter the delivery mechanism of minoxidil, possibly affecting its efficacy. One user mentioned that after switching to a minoxidil formula that included azelaic acid, they did not see the same level of regrowth as with standard minoxidil, though it was unclear if this was due to the added ingredient or other factors.

Overall, community feedback suggests that while some people report benefit from combining azelaic acid with minoxidil or hair loss shampoos, others experience irritation or potential drawbacks. It may be best to patch-test any new combination before applying it widely to the scalp.

Conclusion

Combining azelaic acid with minoxidil or hair loss shampoos could be an attractive option for some people, but results may vary depending on the individual. Minoxidil is an approved treatment for androgenetic alopecia; azelaic acid's anti-DHT effect has been shown only in the laboratory, and no study has tested whether combining the two works better than either alone. It is essential to consult a dermatologist before starting any combination treatment, as side effects can vary and treatment should be personalized for each case.

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/

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://doi.org/10.33192/smj.v75i12.266001

Messenger, A. G., & Rundegren, J. (2004). Minoxidil: Mechanisms of Action on Hair Growth. British Journal of Dermatology, 150(2), 186-194. https://doi.org/10.1111/j.1365-2133.2004.05785.x

Piérard-Franchimont, C., De Doncker, P., Cauwenbergh, G., & Piérard, G. E. (1998). Ketoconazole shampoo: effect of long-term use in androgenic alopecia. Dermatology, 196(4), 474–477. https://pubmed.ncbi.nlm.nih.gov/9669136/