This compares INKEY's standard 10% serum, not its separate 20% Niacinamide Serum. Both standard serums target excess oil and visible pores, so choosing between them is not a two serum assignment handed down by the skincare industry.134

What is actually different?

DetailThe OrdinaryThe INKEY List
Niacinamide strength10%10%
Formula differences1% zinc PCA; German ingredient list includes pentylene glycol and tamarind seed gum.Includes hyaluronic acid, glycerin, squalane, panthenol and allantoin.
TextureWater based serum; can feel sticky or pill with too much product or unsuitable layering.Lightweight serum described as easy to layer with skincare and makeup.
DirectionsA few drops morning and evening, before oils and heavier moisturizers.A pea sized amount after cleansing and hydrating, morning and evening.
Listed pricesGermany: €6.00, with 30 ml and 60 ml options shown.US: $13.00 for 30 ml. UK: £12.00 for 30 ml.
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The prices are in three currencies, so lining up the numbers alone gives arithmetic a job it cannot do. Compare the same bottle size in your own market before deciding which costs less.5

Which should you pick?

For oily skin, either fits the brief. The Ordinary combines niacinamide with zinc PCA to help balance excess oil, while also targeting dullness and uneven texture. INKEY combines oil control with lightweight hydration from hyaluronic acid. Choose by the supporting formula and how the serum fits your routine, rather than treating the shared 10% as a deciding factor. INKEY's separate 20% serum is aimed at oiliness across the whole face; the brand directs combination skin or an oily T zone toward its 10% version.123

How do you use them?

  1. 1Cleanse your face. For INKEY, apply your hydrating serum before niacinamide.
  2. 2Apply your chosen serum. The Ordinary suggests 2 to 3 drops for the face and neck; INKEY's main directions specify a pea sized amount for the face and neck.
  3. 3Let the serum absorb before adding another layer. With The Ordinary, excess product and incorrect layering can contribute to stickiness or pilling.
  4. 4Follow with moisturizer. Keep The Ordinary before oils and heavier creams, and finish your morning INKEY routine with sunscreen.
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What if your skin is sensitive?

Both brands list their 10% serums as suitable for sensitive skin and advise patch testing. The Ordinary suggests starting 1 to 2 days a week if you are concerned about irritation, then increasing frequency gradually. INKEY suggests starting with evening use only. The Ordinary's German directions say to rinse off, stop using the serum and consult a doctor promptly if irritation occurs. INKEY lists its 10% serum as suitable during pregnancy and breastfeeding.1456

Can you use them with other actives?

The Ordinary advises keeping its serum separate from direct and indirect vitamin C, but allows pairing with hyaluronic acid, retinoids and salicylic acid. INKEY allows retinol and suggests applying its 10% niacinamide first. INKEY's acid directions conflict: its warning says to avoid exfoliating acids, while its FAQs allow salicylic and glycolic acid. Use separate routines if you want to avoid that ambiguity. INKEY also advises avoiding high strength vitamin C, with an exception for its own 15% Vitamin C + EGF Serum.1246

How soon should you expect a change?

INKEY gives 1 to 2 weeks for noticeable oil control with its 10% serum. The Ordinary describes smoother looking skin within one week and reduced visible pores and excess oil with regular use. These are different product expectations, not a reason to declare one serum faster.56

Where this answer comes from

  1. 1Product Spotlight: Niacinamide 10% + Zinc 1%theordinary.com
  2. 210% Niacinamide Serum for Oily Skin & Porestheinkeylist.com
  3. 320% Niacinamide Serum | Oil Control Serumuk.theinkeylist.com
  4. 410% Niacinamide Serum for Oily Skin & Porestheinkeylist.com
  5. 5Niacinamide 10% + Zinc 1%theordinary.com
  6. 610% Niacinamide Serum for Pores & Oil Controluk.theinkeylist.com