Face Serum Guide: Retinol, Glycolic Acid, Niacinamide or Vitamin C?
Retinol, glycolic acid, niacinamide and vitamin C are the four serums most routines are built on. This guide matches each to a skin goal and maps out when to use them, morning or night.
If you have ever stood in front of a wall of serums wondering which one you actually need, you are not alone. Four ingredients come up again and again: retinol, glycolic acid, niacinamide and vitamin C. Between them they cover most of what people want from skincare: smoother texture, fewer clogged pores, a more even tone and a bit more glow.
The catch is that they work differently, suit different times of day, and some do not like being used together. Buying all four at once and layering them every night is one of the fastest routes to a sensitised face.
This guide is the map. It matches each serum to a goal, shows where it fits in a morning or evening routine, and helps you pick a sensible first one. If your routine has already got out of hand, our guide to simplifying a ten-step routine is a good reset.
Start with your goal, not the ingredient
Pick the one thing you most want to change in the next three months:
Fine lines, rough texture, or adult breakouts with clogged pores: retinol.
Dullness and rough texture, and you want a quicker visible glow: glycolic acid.
Oiliness, blotchiness, general unevenness or sensitive skin: niacinamide.
Dullness and you want daytime antioxidant support under sunscreen: vitamin C.
If more than one applies, start with the gentlest option that covers your main concern. Niacinamide is the most forgiving; retinol and glycolic acid need the most care.
Retinol: the long game for texture and lines
Retinol is a vitamin A derivative that speeds up skin cell turnover. Over months it may help with fine lines, uneven texture, clogged pores and marks. It is also the ingredient most likely to cause dryness and peeling at first.
When to use: night only. Retinol can make skin more sun-sensitive, and some forms break down in light.
How to start: two or three nights a week, a pea-sized amount on dry skin, followed by moisturiser. Build up slowly over several weeks. Our guide to retinol mistakes beginners make covers the common pitfalls, and retinol percentages explained helps you choose a strength.
Options to consider:
CeraVe Resurfacing Retinol Serum
CeraVeCeraVe Resurfacing Retinol Serum 30mlCeraVe Resurfacing Retinol Serum 30ml is a facial serum in a 30ml pack.S$36.85 uses encapsulated retinol in a barrier-friendly base, a reasonable first retinol for many people.The Ordinary Retinol 0.2% In Squalane Serum
The OrdinaryThe Ordinary Retinol 0.2% In Squalane Serum 30mlThe Ordinary Retinol 0.2% In Squalane Serum 30ml is a 30ml retinol facial serum.S$19.84 is a low-strength, oil-based option; the squalane base feels nourishing in air-conditioning.Olay Regenerist Night Serum - Retinol 24
OlayOlay Regenerist Night Serum - Retinol 24 30mlOlay Regenerist Night Serum - Retinol 24, 30ml.S$36.96 is a widely available drugstore night serum.La Roche-Posay Retinol B3 Serum
La Roche-PosayLa Roche-Posay Retinol B3 Serum All Skin Types 30mlLa Roche-Posay Retinol B3 Serum All Skin Types 30ml is a facial serum in a 30ml pack.S$64.45 pairs retinol with niacinamide, convenient if you want both in one step.
Avoid retinol if you are pregnant or trying to conceive, and pause it before waxing or certain treatments.
Glycolic acid: faster glow, more care needed
Glycolic acid is an alpha hydroxy acid (AHA) that loosens the bonds between dead surface cells, so they shed more easily. The result is often visible quite quickly: smoother, brighter-looking skin. Overuse leads to stinging, redness and a compromised barrier.
When to use: usually at night, two or three times a week to start. Always wear sunscreen the next morning, as AHAs can increase sun sensitivity.
Options to consider: L'Oréal Paris Glycolic Bright Instant Glowing Serum
L'Oréal ParisL'Oréal Paris Glycolic Bright Instant Glowing Serum 30mlL'Oreal Paris Glycolic Bright Instant Glowing Serum: For facial skin care; apply according to the directions on the selected pack.S$54.56 is a popular drugstore serum in a range that also includes cleansers and creams.
Tip: do not use glycolic acid on the same night as retinol when you are starting out. Alternate nights instead. Our guide on how often to exfoliate explains how to find your skin's limit.
Niacinamide: the easy all-rounder
Niacinamide (vitamin B3) is gentle, stable and compatible with almost everything. It is used for oiliness, the look of pores, blotchiness and uneven tone, and may support the skin barrier.
When to use: morning, night or both. It slots into almost any routine.
Options to consider: The Ordinary Niacinamide 10% + Zinc 1% Serum
The OrdinaryThe Ordinary Niacinamide 10% + Zinc 1% Serum 30mlThe Ordinary Niacinamide 10% + Zinc 1% Serum 30ml is a 30ml facial serum.S$15.88 is a simple serum that suits oily, humid-weather skin. If your skin is sensitive, a lower-strength formula may feel more comfortable. Our article on niacinamide's benefits and limits is worth reading if 10% has made you flush before.
Vitamin C: the morning antioxidant
Vitamin C is an antioxidant used for dullness and uneven tone, and it complements sunscreen during the day. Pure forms can tingle and oxidise; derivatives are gentler.
When to use: morning, after cleansing and before moisturiser and sunscreen.
Options to consider: CeraVe Skin Renewing Vitamin C Serum
CeraVeCeraVe Skin Renewing Vitamin C Serum - 30mlCeraVe Skin Renewing Vitamin C Serum is a 30ml facial serum with 10% vitamin C.S$39.49 is a 10% vitamin C serum from a barrier-focused brand. Keep the bottle closed and away from heat; Singapore bathrooms are warm and humid, which speeds up oxidation. For more detail, see our vitamin C guide for real life.
The AM/PM map
Here is a simple way to place each serum.
Morning:
Cleanse or rinse
Vitamin C or niacinamide
Moisturiser
Sunscreen
Evening:
Cleanse
Retinol or glycolic acid (on different nights), or niacinamide on rest nights
Moisturiser
Pairing rules that keep skin calm
Retinol and glycolic acid: alternate nights, not the same night, at least at first.
Vitamin C and retinol: split them, vitamin C in the morning and retinol at night.
Niacinamide and vitamin C: fine together for most people. If you flush, use them at different times of day.
Niacinamide with retinol or acids: generally fine and may make the routine more comfortable.
Benzoyl peroxide: keep it separate from retinol. See combining retinol with vitamin C, acids and benzoyl peroxide.
Where hydrating serums fit
If your skin is tight or irritated, an active serum may not be the right first move. A hydrating, calming serum such as La Roche-Posay Hyalu B5 Suractivated Serum
La Roche-PosayLa Roche-Posay Hyalu B5 Suractivated Serum 30 mLHydrating gel serum with a hyaluronic acid complex, panthenol and madecassoside.S$72.49 can sit in the routine any time, and can be the only serum for a while if your barrier needs a break. If you are in that situation, see our guide to skin that is tired of too many actives.
Common mistakes
Starting two actives in the same week. If you react, you will not know which one caused it.
Judging too early. Give niacinamide and vitamin C 8 to 12 weeks, and retinol three to six months.
Skipping sunscreen. Retinol and glycolic acid make it essential, and every brightening serum depends on it.
Using more product. A few drops cover the face. More just raises the risk of irritation.
FAQ
Which serum should a beginner start with?
Niacinamide is usually the easiest first serum. If your main goal is lines or texture and your skin is not sensitive, a low-strength retinol at night is a good second step.
Can I use all four?
You can, but not all at once and not all on day one. Many people settle on two: vitamin C or niacinamide in the morning, and retinol or glycolic acid at night.
Do serums work in humid weather?
Yes. Humid weather simply means you may need a lighter moisturiser on top. Lightweight serums suit Singapore well.
Bottom line
Choose a serum for one clear goal: retinol for long-term texture and lines, glycolic acid for faster glow, niacinamide for oil and blotchiness, and vitamin C for morning brightness. Keep vitamin C to the morning, retinol and glycolic acid to alternating nights, and wear sunscreen every day. One well-chosen serum used consistently beats four used chaotically.
