If you've just added retinal to your night time skincare routine, the biggest question is usually: how much, how often, and what could go wrong? Start small—apply a pea-sized amount to clean skin, always at night, since retinal is sensitive to sunlight and can lose potency (or increase sun sensitivity) if applied during the day. Begin with two to three nights a week rather than nightly, letting your skin build tolerance before increasing frequency. If you have sensitive skin, it's worth doing a patch test before your first full application, just to confirm how your skin responds.
A few cautions are worth keeping in mind. Mild dryness, flaking, or slight tingling in the first few weeks is common and usually temporary—but layering retinal with other strong actives like AHAs, BHAs, or vitamin C on the same night can overwhelm the skin barrier and worsen irritation, so it's best to alternate nights instead. Daily SPF is non-negotiable while using any retinoid, since retinal increases photosensitivity even though it's applied at night. And if you're pregnant, breastfeeding, or have a known retinoid sensitivity, check with a dermatologist before starting.
Once your skin adjusts, most people can work up to nightly use, always finishing with a moisturizer to lock in hydration and ease any residual dryness. Consistency is what delivers visible results over time.
Ready to build your routine the right way? KSECRET’s SEOUL 1988 Retinal 1% Cream is a great starting point if you want a very gentle formula, while the Retinal 2% Serum suits those with more average skin tolerance looking for a step up.