Azelaic Acid–Induced Burning and Erythema in Sensitive Skin, Rosacea, and Eczema
Topical azelaic acid commonly causes burning/stinging/tingling and erythema as dose- and barrier-dependent local irritation. [1], [2] The reactions are more likely when skin barrier function is impaired or when application occurs to inflamed or broken facial skin. [1], [3]
Local Irritant Contact Dermatitis Mechanisms
Azelaic acid can produce transient skin irritation after application, particularly to broken or inflamed skin. [1] This irritation manifests clinically as burning/stinging/tingling, erythema, scaling, pruritus, and dryness in some patients. [1], [2], [4]
Formulation- and pH-Related Effects on Nociceptor Signaling
Azelaic acid products have labeling that attributes early irritation, in part, to the low pH of azelaic acid, which increases stinging in susceptible skin. [5] Low-pH exposure on compromised epithelium increases the likelihood of pain and erythema through local irritation of superficial tissues. [5]
Skin Barrier Dysfunction in Eczema
Eczema involves impaired epidermal barrier function and active inflammation, which increases susceptibility to irritant reactions from topical products. [3] When azelaic acid is applied to inflamed skin, the risk of irritation and burning is increased because irritation occurs more readily on broken or inflamed skin. [1]
Rosacea Skin Reactivity and Barrier Impairment
Rosacea skin frequently experiences sensations such as burning, stinging, or tearing during flares and with triggers, including topical exposures that provoke facial sensitivity. [6] Rosacea is associated with facial skin fragility and heightened reactivity, which increases the probability that azelaic acid–induced irritation presents as erythema and burning. [6] In clinical trials of topical azelaic acid in papulopustular rosacea, burning and stinging were common treatment-related cutaneous adverse events. [4]
Role of Baseline Facial Irritation and “Starting” Symptoms
In randomized rosacea studies, baseline facial skin symptoms such as burning and scaling were common, which supports that azelaic acid is more likely to be perceived as irritating on already reactive skin. [7] In those trials, pretreatment stinging/burning-type sensations occurred frequently in both treatment arms, consistent with high baseline facial irritability in this population. [7]
Relative Incidence and Reported Cutaneous Adverse Reactions
For azelaic acid gel 15%, burning/stinging/tingling is a commonly reported adverse reaction (reported at 29%). [1] For azelaic acid gel 15%, erythema/irritation is reported (reported at 4%). [1] Scaling/dry skin/xerosis and pruritus are also reported with meaningful frequency, which often accompanies erythema and stinging in practice. [1]
Clinical Implication for Sensitive-Skin Use
Azelaic acid should be avoided on clearly broken or severely inflamed skin when early burning and erythema occur, because labeling notes irritation is more likely on broken or inflamed skin. [1], [5] If continuing therapy, early reactions typically represent irritant effects rather than an allergic process, consistent with the formulation- and barrier-dependent pattern described in labeling and reviews. [1], [5]