L'Oréal face serum: which to choose and how to use it

Which ingredient matches your goal?

Start with the concern you most want to address, then choose a product suited to your skin type. Choose for the concern you want to address rather than the grandest promise on the box, which is not a competitive sport. Retinoid is the umbrella term for vitamin A based skincare ingredients; retinol is one member of that group.1

What should you look for in a vitamin C serum?

Look for ascorbic acid or L ascorbic acid on the ingredient list. For these forms, a concentration of 10% to 20% is a useful selection range; above 20% raises the risk of significant irritation. Sensitive skin calls for a lower concentration. Those numbers are general selection guidance, not a reason to assume an unnamed L'Oréal serum contains that strength. Vitamin C acts as an antioxidant, helping protect skin cells from damage caused by unstable molecules called free radicals. It also supports collagen, the protein that gives skin structure, and can fade dark spots. Choose dark or tinted packaging because vitamin C is sensitive to light and heat.4

Vitamin C can be used daily and is also suitable for nighttime use, but morning application pairs it with sunscreen. Vitamin C adds protection; it does not replace sunscreen. Expect about three months to see its effects rather than an immediate change. A photograph without makeup, followed by another each month, can help you judge progress. Dark spot improvements can fade after you stop using vitamin C.24

How should you start a retinol serum?

Retinol and retinaldehyde are cosmetic retinoids that can reduce fine surface wrinkles and lighten pigmentation. Retinoids help preserve existing collagen and stimulate new collagen formation. Cosmetic retinol is not interchangeable with prescription treatments such as tretinoin or adapalene. Start with a minimal amount on alternate nights rather than using a large amount every night. Topical retinoids frequently cause irritation, and excessive use can cause redness and peeling. They can also increase the risk of sunburn. A light moisturizer can help manage dryness.3

General retinoid guidance is to cleanse before bed, wait 20 to 30 minutes, then apply the treatment. If dryness is a problem, apply a moisturizer that will not clog pores immediately after washing, then apply the retinoid 20 to 30 minutes later. Follow your exact serum's label for its amount and schedule.1

Where does the serum go in your routine?

1. 1Wash with a gentle cleanser and gently pat your face dry.
2. 2Apply your treatment after cleansing. For a morning vitamin C serum, this is its place before moisturizer. Use the separate nighttime timing above for a retinoid.
3. 3Apply moisturizer. In general, lighter products go before thicker creams so the thinner product can reach your skin.
4. 4In the morning, finish skincare with broad spectrum, water resistant sunscreen rated SPF 30 or higher. Apply it 15 minutes before going outdoors.
5. 5Apply makeup after skincare, if you wear it.

Makeup goes on after skincare, so the routine has an end even if the bathroom shelf does not.5

Can you combine it with other treatments?

Use one serum at a time rather than introducing several new treatments together. Vitamin C and chemical exfoliants such as alpha hydroxy acids can affect the skin's pH balance when mixed. Do not automatically layer a vitamin C serum with a glycolic acid treatment. More products mean more opportunities for dryness and irritation. If you already use a prescribed skin treatment, keep its instructions in charge of the routine and ask your prescriber where an additional serum belongs. General layering guidance puts medication immediately after cleansing, but a prescription's specific directions take priority.25

Who should be careful, and when should you stop?

Introduce new products sparingly, test them before adding them to your routine, and avoid heavily fragranced products if your skin is sensitive. Stop using a product that causes irritation. Arrange a dermatologist appointment if you develop an irritated rash or signs of contact dermatitis, meaning skin inflammation triggered by contact with a substance. Skincare can cause stinging, burning or allergic reactions, not just temporary dryness. Persistent dermatitis needs medical assessment. During pregnancy, prescription topical tretinoin, isotretinoin and adapalene should not be used; discuss retinoid serum selection with your clinician before starting.23