After applying azelaic acid, it is generally recommended to wait for about 10 to 15 minutes before applying moisturizer. This waiting period allows the azelaic acid to fully penetrate the skin and exert its beneficial effects. Additionally, it helps to minimize any potential interactions between the acid and the moisturizer, ensuring optimal efficacy of both products. However, it's always best to follow the specific instructions provided by the product manufacturer or consult with a dermatologist for personalized advice based on your skin type and condition.