Why use a face serum?

What makes a serum different?

Serums are usually light liquids made with oil or water, designed to absorb quickly and deliver concentrated ingredients. A few drops typically cover the face. The base carrying those ingredients matters too: other ingredients can change how much reaches the skin and how strongly the formula acts. A serum's usefulness depends on its formula, not the ceremonial importance of its dropper.13

Choose the benefit before the bottle

• For dryness, hyaluronic acid is a humectant, meaning it retains water in the skin. Ceramides help keep moisture from escaping. A hydrating serum can add moisture, but keep moisturizer in the routine.
• For dark spots and fine lines, topical vitamin C can improve their appearance. Its brightening effects are promising, although more research is needed. Vitamin C also acts as an antioxidant, helping counter unstable molecules called free radicals that damage skin.
• For fine surface wrinkles and pigmentation, retinol and retinaldehyde can help by reducing collagen loss and encouraging new collagen formation. These ingredients can irritate skin, so strength and frequency matter.

Choose by ingredients and formulation rather than price. Ingredients matter more than price, even when the bottle appears to have its own luxury apartment. For vitamin C, look for ascorbic acid or L ascorbic acid at 10% to 20%; sensitive skin should start at the lower end. Choose dark or tinted packaging because vitamin C is sensitive to light and heat.125

Where does serum go in your routine?

1. 1Wash your face with a gentle cleanser and gently pat dry.
2. 2Apply your serum after cleansing and before moisturizer. A few drops are usually enough for the face; vitamin C can also be applied to the neck.
3. 3Apply moisturizer, then sunscreen in the morning.
4. 4Apply makeup afterwards, if you wear it.

Frequency depends on the active ingredient. Vitamin C fits well in the morning because it works alongside sunscreen. Start every other day and increase to daily use if tolerated. For topical retinoids, begin with a minimal amount on alternate nights to reduce irritation. Adding several products aimed at aging can irritate skin rather than improve the result.2567

How long before you see a difference?

Hydration can improve sooner than changes in pigmentation or wrinkles. In a trial involving 40 women, one hyaluronic acid serum increased measured hydration immediately after application, with improvements in smoothness and fine lines after six weeks of twice daily use with sunscreen. Vitamin C takes about three months of consistent use to show noticeable effects. Monthly photographs without makeup can help you track gradual changes.245

Cosmetic formulas aimed at aging have uncertain results, and marketing claims can outrun their actual effects. The word serum is not a scientific qualification, however confidently it occupies the front of the bottle.6

Who should be careful?

Test a small area before applying a serum widely, especially with sensitive skin. Combining acidic serums with other acids, or adding a retinol serum alongside a prescription retinoid cream, can cause irritation. Vitamin C can cause dryness, itching or redness; stop using it and speak to a doctor if discomfort or irritation is substantial. Prescription tretinoin, isotretinoin and adapalene should not be used during pregnancy.1256