Why does azelaic acid cause burning and erythema, particularly in individuals with sensitive skin, rosacea, or eczema?

Why Azelaic Acid Causes Burning and Redness

Azelaic acid causes burning and redness because of its low pH formulation, which temporarily irritates the skin, especially when applied to broken or inflamed skin—this is a normal, expected side effect that typically subsides within the first 3 weeks of continued use. 1

Mechanism of Irritation

• The low pH of azelaic acid formulations is the primary cause of temporary skin irritation, including pruritus, burning, stinging, tingling, and erythema 1
• This irritation occurs most commonly at the start of treatment and is more pronounced when the product contacts broken or inflamed skin 1
• The burning sensation is a direct chemical irritation rather than an allergic reaction in most cases 2, 3

Expected Timeline and Pattern

• Local irritation is typically most pronounced during the first 3 weeks of treatment but generally decreases with continued use 3
• These side effects are generally mild and transient, not usually necessitating discontinuation of therapy 4
• If you continue treatment through this initial period, the irritation commonly subsides as your skin develops tolerance 1

Risk Factors for Increased Irritation

• Sensitive skin conditions: Patients with rosacea, eczema, or inherently sensitive skin experience more pronounced burning and redness 3
• Combination with other irritants: Concomitant use of other potentially irritating topical products (sulfur, resorcinol, salicylic acid, retinoids, or benzoyl peroxide) increases irritation risk 2
• Environmental factors: Exposure to sunlight, sunlamps, wind, or cold weather exacerbates irritation 2
• Application technique: Applying to broken or inflamed skin intensifies the burning sensation 1

Management Strategy to Minimize Burning

• If irritation is troublesome: Reduce application frequency to once daily instead of twice daily until tolerance improves 1
• For severe irritation: Apply only once every two days, then gradually increase frequency as tolerance develops 3
• Proper application technique: Clean skin with a gentle, non-medicated cleanser before applying azelaic acid 3
• Timing with other products: When using multiple topical agents, apply them at different times of the day to minimize cumulative irritation 3
• Avoid sensitive areas: Keep azelaic acid away from the mouth, eyes, and other mucous membranes 1

When to Discontinue

• If sensitivity or severe irritation develops and persists despite reducing application frequency, treatment should be discontinued and appropriate therapy instituted 1
• If eye irritation occurs after accidental contact, wash eyes with large amounts of water and consult a physician if irritation persists 1
• Contact dermatitis may occur as a side effect requiring discontinuation 3

Important Distinction

• The burning and redness you experience are not signs of treatment failure or skin damage—they represent the expected pharmacological effect of the low pH formulation 1
• This differs from true allergic contact dermatitis, which would require permanent discontinuation 2, 3
• Most patients who persist through the initial 3-week irritation period achieve successful treatment outcomes, with 51% success rates at 12 weeks 3