La Roche-Posay Vitamin C12 Serum

La Roche-Posay recommends the daytime. Apply it after cleansing, before moisturizer and sunscreen, so its antioxidant care works through the day.

Yes, but split them: Vitamin C12 Serum in the morning and retinol products in the evening. If you use retinol during the day, always wear sunscreen.

Pure vitamin C can react on contact with air and turn yellow. La Roche-Posay says it is still effective, and recommends storing the serum at normal room temperature.

It is designed for all skin types, but the brand says it is better suited to normal and dry skin. For oily and combination skin, La Roche-Posay makes a separate oil control version.

Yes. La Roche-Posay lists it as suitable for sensitive skin, and as non-comedogenic, oil-free and paraben-free.

Three to four drops on the face and neck, avoiding the eye area. Massage in gently with your fingertips, then follow with moisturizer and SPF.

An ultra-light, non-greasy serum that absorbs fast. La Roche-Posay describes it as a rich gel-serum that leaves skin feeling softer and more hydrated.

Opened skincare can't be resold, so it is returnable only if it arrived damaged or was the wrong item. Sealed and unopened, you have 30 days from delivery to start a return.