To prevent azelaic acid from pilling, it is important to follow a few key steps:

1. Cleanse and exfoliate: Start with a clean and exfoliated face to ensure there are no dead skin cells or excess oils that could contribute to pilling.

2. Layering order: Layer your skincare products in the correct order. Azelaic acid should generally be applied after cleansing and toning but before moisturizing. This allows it to penetrate the skin effectively without any barriers.

3. Use the right amount: Apply only a pea-sized amount of azelaic acid to your face. Using too much product can increase the chances of pilling.

4. Allow absorption time: Give your skin enough time to fully absorb the azelaic acid before applying any subsequent products. This usually takes a few minutes.

5. Pat, don't rub: Instead of rubbing the product into your skin, gently pat it in using your fingertips. This helps to ensure even distribution and minimize the risk of pilling.

6. Choose compatible products: Some skincare products may not work well together and can lead to pilling. Avoid using heavy oil-based moisturizers or silicone-based products immediately after applying azelaic acid, as they can create a slippery surface that causes pilling. Opt for lightweight, water-based moisturizers instead.

7. Sunscreen last: If you use sunscreen during the day, apply it as the last step of your skincare routine. This helps to create a protective barrier over the azelaic acid and reduces the chances of pilling.

Remember, everyone's skin is different, so it may take some trial and error to find the best routine that works for you. If pilling continues to be a problem, consider consulting with a dermatologist for personalized advice.