K-Secret

Soul 1988 Serum.

Serums

About this product

A 15% niacinamide brightening serum formulated with squalane and panthenol.

Full ingredients

Panax Ginseng Root Extract, Water, Glycerin, Dipropylene Glycol, Caprylic/Capric Triglyceride, 1,2-Hexanediol, Niacinamide, Butylene Glycol, Methyl Gluceth-20, Polyglyceryl-3 Methylglucose Distearate, Hydrogenated Lecithin, Sorbitan Stearate, Ammonium Acryloyldimethyltaurate/VP Copolymer, Macadamia Ternifolia Seed Oil, Carbomer, Tromethamine, Betaine, Tocopherol, Ethylhexylglycerin, Helianthus Annuus (Sunflower) Seed Oil, Adenosine, Disodium EDTA, Cholesterol, Polyglyceryl-10 Oleate, Brassica Campestris (Rapeseed) Sterols, Phytosteryl/Behenyl/Octyldodecyl Lauroyl Glutamate, Retinal, Silica, Aluminum/Magnesium Hydroxide Stearate, Potassium Cetyl Phosphate, Pentaerythrityl Tetra-Di-T-Butyl Hydroxyhydrocinnamate, Arctium Lappa Root Extract, Cnidium Officinale Root Extract, Dioscorea Japonica Root Extract, Paeonia Suffruticosa Root Extract, Rehmannia Chinensis Root Extract, 3-0-Ethyl Ascorbic Acid, Bakuchiol, SH-Oligopeptide-1

Guru Score

78%

Approved

Early verdict · Few reviews so far

2Gurus

1Approved

1Mixed

0Skip

What they liked

Hydrating, plumping feel that absorbs without heaviness
Brightening glow without irritating sensitive skin
Moisturizing texture despite high niacinamide content

What they flagged

High niacinamide may irritate those sensitive to it

What the gurus are saying

This 15% niacinamide serum has an unexpectedly hydrating, moisturizing texture for a brightening product, thanks to squalane and panthenol. It brings the complexion back to life with a reviving glow. Anyone prone to niacinamide sensitivity should wait until skin is fully dry before applying, as moisture speeds absorption and may overload your skin with this high concentration.

Synthesized from 2 expert reviews · most recent take November 2025

Best for

Oily skin Sensitive skin Acne-prone skin

Type

SerumsDrops & dropper

Key actives

Vitamin C Retinoid NiacinamideVitamin EPeptides

Formula notes

Fragrance-freeNo drying alcohol

Where to buy

Amazon → Google → iHerb →

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How it works Independent by design. Every take comes from a creator we have no relationship with. We do not ask anyone to review, and affiliate links never move a score.

What the gurus are saying.

Every take we've logged from this product's reviews across YouTube. Click any row to watch the moment they said it.

All takes Approved takes Critical takes Mixed takes Hide sponsored

AliceintheRabbitHole

59k subs

✓Mixed

"This is a 15% niacinamide serum, so I wait until my skin is fully dry before applying it, because if you have moist skin it will absorb the applied skincare faster and I don't want to flood my skin with niacinamide. Not everybody has niacinamide sensitivity, some people can use these higher levels with no problem, but I'm a bit more sensitive and I find I can max out on niacinamide and irritate my skin, so that's the reason for the caution, if it works for you that's fantastic. This does feel nice though. It's a brightening product with a high level of niacinamide, but I see ingredients like squalane and panthenol which I feel are helping to explain that lovely texture. I expected the feel to match the sensation of most brightening products, but it felt more like a hydrating, moisturizing product."

Gothamista

684k subs

✓Approved

"When you apply it, it feels so hydrating and plumping on the skin. It's almost like a very light refreshing gel, but it does absorb, it sinks in, it's slightly moisturizing. This also gives my skin a really beautiful glow. This is great for this time of year because it is slightly moisturizing but it's not heavy. I love that it clearly brings my skin back to life. It revives my complexion. The black genen is working, and it's possibly working here too, along with all the other ingredients like the eye formula. This is a well-aging powerhouse for those with very sensitive skin. This has gone through skin sensitivity testing as well."

What the evidence says.

Independent of what the gurus think, this is what the published research supports about the main active ingredients here.

Retinoids

Retinoids are among the best studied ingredients in dermatology, with solid evidence for acne and for the fine lines and rough texture that come from sun exposure. Dryness and flaking in the first few weeks are common and usually settle.

Source: DermNet

Vitamin C

Topical vitamin C is an antioxidant with reasonable evidence for dullness and uneven tone. It breaks down in light and air, so how a product is formulated and packaged matters as much as the percentage on the front.

Source: DermNet

Niacinamide

Niacinamide has evidence behind it for redness, uneven tone and supporting the skin barrier, and it is usually well tolerated even by skin that reacts to most things.

Source: DermNet

Frequently asked.

What is K-Secret Soul 1988 Serum?

A 15% niacinamide brightening serum formulated with squalane and panthenol.

Is K-Secret Soul 1988 Serum worth it?

Mostly yes. 1 of the 2 gurus who reviewed it give it their stamp of approval, for a Guru Score of 78%.

What is K-Secret Soul 1988 Serum's Guru Score?

K-Secret Soul 1988 Serum holds a Guru Score of 78%. That is our read on how warmly the experts talk about it, based on the verdicts of 2 expert reviewers we have collected.