Niacinamide vs vitamin C, and the myth they cancel each other out

The short answer

You can (and probably should) use both. Niacinamide and vitamin C work on different mechanisms and complement each other rather than cancelling out. The internet myth that they neutralise each other comes from a 1960s lab artefact under conditions (high heat, unstable nicotinic acid, not nicotinamide) that no modern formulation reproduces.

If you can only pick one to start: vitamin C in the morning if your priority is UV defence and slow brightening; niacinamide if your priority is oil control, redness, and post-inflammatory pigmentation.

Where the myth came from

In 1965, a study examined nicotinic acid (a different form of vitamin B3, not the niacinamide we use today) in the presence of ascorbic acid under high-temperature conditions. The nicotinic acid converted to niacin, which on skin can cause a histamine flush. Half a century of internet skincare advice has been built on that one observation.

Modern formulations use niacinamide, not nicotinic acid. They're stable at room temperature, at the pH ranges used in skincare, and in the presence of ascorbic acid. Lin's 2003 study, and many since, used vitamin C and niacin/niacinamide-adjacent compounds in the same formulation with no efficacy loss.

What each one actually does

Niacinamide

The Hakozaki 2002 study showed niacinamide interrupts the transfer of melanin from melanocytes to keratinocytes. It also (separately) reduces sebum production, supports the skin barrier, and calms inflammation. It is one of the most-tolerated active ingredients in skincare: sensitive skin, acne-prone skin, dry skin, all do fine on it.

Vitamin C (L-ascorbic acid)

The Pullar 2017 review summarises decades of work: vitamin C is a co-factor for collagen synthesis enzymes, a potent topical antioxidant that complements your SPF, and a tyrosinase inhibitor that interrupts melanin synthesis upstream.

In other words: niacinamide stops melanin from being delivered; vitamin C stops it from being made in the first place. They work at different points in the same pathway, which is exactly why they're a strong stack on pigmentation.

How to use them together

The simplest, most-research-aligned routine is:

Morning:

1. Cleanse
2. Vitamin C serum (10–20% L-ascorbic acid)
3. Niacinamide-containing moisturiser
4. SPF

Evening:

1. Cleanse
2. Niacinamide serum (2–5%)
3. Retinol or acid (per your skin cycling plan)
4. Moisturiser

You don't need to wait between layers. You don't need a separate niacinamide serum if your moisturiser already contains it. Stacking is fine.

When to pick just one

• Very reactive skin? Start with niacinamide alone for 4–6 weeks. Add vitamin C in once the barrier feels settled.
• Active acne / oily skin? Niacinamide is the better solo starting point. Sebum, post-inflammatory pigmentation, and redness all tend to benefit.
• Anti-aging focus / photodamaged skin? Vitamin C in the morning + retinol at night is the better solo starting axis. Add niacinamide later.

What about other forms?

L-ascorbic acid is the gold standard for vitamin C, but it's not the only one. Derivatives like sodium ascorbyl phosphate and THD ascorbate are gentler and more stable, but the evidence base is thinner. Stick with L-ascorbic acid if you're after the well-documented results.

For niacinamide, niacinamide is niacinamide: 2–5% in any pH range is fine. Don't pay extra for a "high-strength" 10% version. The clinical studies all used the lower range.

The bottom line

The myth: niacinamide cancels out vitamin C. The reality: they work on different mechanisms, layer fine in modern formulations, and are arguably the most-evidenced antioxidant + pigmentation pair you can put on your skin. Use both. Mornings for vitamin C, all-day for niacinamide.