How to use vitamin C
Apply vitamin C after cleansing and after toner if you use one. Morning is the preferred time because vitamin C works alongside sunscreen, though it is safe to use overnight and can be used daily. Put sunscreen on after other skin care and beneath makeup, giving one small corner of the morning routine an unusually clear queue.23
What to expect from each ingredient
Topical vitamin C can reduce cell damage and support collagen. It can also improve dark spots, but the effect can fade after you stop using it. Visible effects can take about three months. Copper peptides are also described as encouraging hyaluronic acid production and helping firm, smooth and soften skin. Use products consistently to judge results; skin care is not an audition where every bottle gets a monologue.123
How skin irritation changes the plan
For vitamin C serum, look for 10% to 20% L ascorbic acid; higher concentrations risk serious irritation. If your skin is sensitive, start with a low concentration. Initial use can cause stinging or redness, which usually eases with continued use. Stop using a product that irritates your skin.123
If you also use a retinoid
That is a separate case. The Ordinary advises against pairing its retinoids with direct vitamin C and recommends alternating its retinoids and copper peptides to reduce the chance of skin sensitivity. This advice concerns combinations with a retinoid; it does not show that copper peptides and vitamin C conflict with each other. For retinoids during pregnancy or breastfeeding, discuss skincare use with a doctor.4
Where this answer comes from
- 1Popular Skin Care Ingredients Explainedhealth.clevelandclinic.org
- 2Vitamin C Serum: Benefits, How to Applyhealth.clevelandclinic.org
- 3Dermatologist-recommended skin care for your 20saad.org
- 4Your Definitive Guide to Using Retinoidstheordinary.com
