Indeed, azelaic acid has a depigmenting and inhibitory activity against 5-alpha-reductase. As such, it is used topically – at a concentration of 20% – in products intended for the treatment of androgenetic hair loss. In addition to this, azelaic acid has also been shown to be effective in treating other ailments, such as acne and melasma.
More specifically, azelaic acid has:
- Antibacterial properties.
- Inhibitory activity against the proliferation of keratinocytes.
- Anti-inflammatory and anti-radical activity.
- Depigmenting action.
As mentioned, by virtue of its numerous properties, azelaic acid is used in the treatment of various skin disorders and is also used to counteract hair loss.
The anti-acne activity of azelaic acid probably derives from its bacteriostatic and bactericidal action against microorganisms which inhabit the superficial layers of the epidermis, causing skin lesions characteristic of acne vulgaris ( Propionibacterium acnes).
This bacteriostatic and bactericidal action is due to the inhibitory activity of azelaic acid against enzymatic systems essential for the activation of the mitochondrial respiratory chain and for the synthesis of nucleic acids and proteins.
In addition to the above actions, azelaic acid has demonstrated activity radical scavenger (anti free radicals), potentially useful in an anti-aging perspective, but also valuable for counteracting the inflammatory phenomena that accompany acne.
Azelaic acid normalizes the processes of epidermal differentiation and inhibits the proliferation of keratinocytes, leading to a reduction in the content of free fatty acids in the lipids of the skin surface. This characteristic helps to enhance its antiacneic and anticomedogenic action, since it significantly reduces the colonization density of the Propionibacterium acnes.
For all these reasons, azelaic acid is still today considered one of the drugs of first use in the mild forms of acne.
Although the causes of rosacea have not yet been fully clarified, it is believed that inflammatory processes still play a role of fundamental importance in this pathology.
Thanks to its interesting anti-inflammatory properties, azelaic acid has proved to be very useful in the treatment of rosacea.
In detail, the effectiveness of azelaic acid in this area is due to its ability to modulate the inflammatory response at the keratinocyte level through a series of mechanisms, such as:
- Inhibition of the synthesis of pro-inflammatory cytokines;
- The inhibition of the release of reactive oxygen species (free radicals or ROS) by neutrophils;
- An action of “scavenger” of the free radicals already formed (radical scavenger).
As a depigmentant
Azelaic acid exerts an inhibitory action against tyrosinase, a key enzyme for the synthesis of melanin; in this sense, it is active above all at the level of hyperactive melanocytes, while sparing the normal ones. As such, it is widely used in the treatment of melasma.
Against hair loss
It is known that androgenetic alopecia, the most common cause of hair “loss” in both men and women, is linked to the action of androgen hormones in a genetically predisposed terrain. In this sense, the follicular concentration of the enzyme 5-alpha-reductase plays a leading role, which converts testosterone into dihydrotestosterone, the main accused in the genesis of baldness. The studies of Stamatiadis et al. (1987) demonstrated how in vitro azelaic acid possesses a very strong inhibitory activity against the 5-alpha-reductase enzyme; this effect is not direct (as in the case of progesterone), but derives from the inhibition of NADP reductase with blockage of the production of NADPH (key coenzyme of 5-alpha-reductase). Consequently, at the level of the hair bulb, the metabolic fate of testosterone is no longer oriented towards the synthesis of dihydrotestosterone, but towards oxidation to androstenedione and estrone (the latter with a positive effect on hair health).
The association with pyridoxine and zinc seems to enhance the effects of azelaic acid in vitro.
Against skin aging
By virtue of its action against free radicals – therefore of its antioxidant properties – it is believed that azelaic acid can be an effective anti-wrinkle and anti-aging remedy.
Generally, when used as an anti-wrinkle and anti-aging treatment, azelaic acid is included in creamy or oily formulations. However, in these cases, its concentration must necessarily be lower than that used to counteract the ailments mentioned above, in order to avoid unpleasant adverse reactions.
In fact, in anti-aging treatments, the concentration of azelaic acid should be around 3%, against the 10-20% present in products for medical-dermatological use.
Despite being a normally well-tolerated active principle, azelaic acid is however not free from inducing side effects. For this reason, its use should only be made on the advice of and under the supervision of a doctor.
The main undesirable effect induced by azelaic acid is skin irritation which can be associated with:
In the most serious cases – and, above all, in case of improper and/or excessive use of azelaic acid – real burns can also occur in the area of application.
Other side effects include:
- Burning or pain at the application site;
- skin rashes;
- Loss of sensitivity in the treated area;
- Exfoliation of the skin at the application site;
- Depigmentation of the treated area (this is to be considered an undesirable effect when azelaic acid is used in the treatment of acne and rosacea, while it represents a desired effect when used against melasma).
Finally, in sensitive subjects, the use of azelaic acid can cause allergic and sensitization reactions.