Aesthetician and skin expert Alicia Lartey says that azelaic acid “is one of the most slept on multi-purpose ingredients in the skincare world”. As it’s antibacterial, it’s a go-to ingredient for those with acne and can treat those pesky red, pink or purple skin stains left behind by spots. Consultant dermatologist Dr. Anjali Mahto is also a fan of azelaic acid for brightening skin. This serum calmed down a couple of very angry, red jawline spots but I used it sparingly — just twice a week at night, as 15% is very strong and can cause uncomfortable tingling. The countless five-star reviews speak for themselves, though. “Been using this for 4 months now and have seen a big reduction in hyperpigmentation. Skin is the most even it’s ever been,” wrote one user. If you’re using any acid-based products, it’s important to wear sunscreen during the daytime, as they can make skin sensitive to sunlight.