NUMBUZIN No.5 Glutathione Vitamin Concentrated Serum

NUMBUZIN No.5+ Glutathione Vitamin Concentrated Serum

Brighten dull-looking skin and help improve the appearance of dark spots with the NUMBUZIN No.5+ Glutathione Vitamin Concentrated Serum, a lightweight daily serum designed to support a clearer, more even-looking complexion. This intensively concentrated brightening formula targets the look of hyperpigmentation, post-acne marks, dark spots, and uneven tone while leaving the skin feeling hydrated and smooth.

Formulated with a comprehensive brightening vitamin complex including glutathione, niacinamide (50,000ppm), panthenol (50,000ppm), tranexamic acid (40,000ppm), 3-O-ethyl ascorbic acid (stable vitamin C), alpha-arbutin, alpha-bisabolol, adenosine, Coenzyme Q10 (ubiquinone), alpha lipoic acid, beta-glucan, and ceramide NP, this serum approaches visible pigmentation and discoloration from multiple simultaneous angles. Glutathione helps interrupt melanin synthesis at its source for a more even-looking tone. Niacinamide refines texture and fades the look of dark spots. Stable vitamin C (3-O-ethyl ascorbic acid) brightens and provides antioxidant protection. Tranexamic acid and alpha-arbutin help further target the look of stubborn pigmentation and post-blemish marks. Panthenol and ceramide NP support hydration and skin comfort throughout the treatment.

The NUMBUZIN No.5+ Glutathione Vitamin Concentrated Serum is a great choice for anyone looking for a K-beauty brightening serum, a dark spot serum, or a daily serum for acne marks and uneven skin tone. Its lightweight texture layers easily into both morning and evening routines — part of NUMBUZIN's numbered, concern-specific "What's Your Number?" approach to targeted skincare.

Size: 30ml / 1.01 fl. oz

Overview

The NUMBUZIN No.5+ Glutathione Vitamin Concentrated Serum is a daily brightening treatment created to help support clearer-looking skin, improved radiance, and a more even-looking complexion. Designed for all skin types, it is especially helpful for concerns including hyperpigmentation, dark spots, acne scars, post-blemish marks, and dull-looking skin.

Study results

According to the brand's reported clinical results, this serum showed:

• 18.90% improvement in skin tone evenness
• 9.65% reduction in dark spots after 4 weeks
• Clinically proven improvement in skin texture and brightness within 2 weeks

The brand also notes that hypoallergenic and skin irritation tests were completed, and that the formula is suitable for sensitive and acne-prone skin. Individual results may vary.

Key benefits

• Helps improve the look of dark spots and hyperpigmentation
• Supports a brighter, more even-looking complexion
• Helps improve the appearance of acne scars and post-blemish marks
• Multi-active formula: glutathione, niacinamide (50,000ppm), tranexamic acid (40,000ppm), stable vitamin C, alpha-arbutin, Coenzyme Q10, and more
• Includes panthenol (50,000ppm) and ceramide NP for soothing hydration
• Suitable for all skin types, including sensitive and acne-prone skin

How to use

After cleansing and toning, apply an appropriate amount to the face and gently pat until absorbed. For targeted care, apply an extra drop directly to areas of concern and tap in gently. Follow with moisturizer. In the daytime, always apply broad-spectrum sunscreen as the final step — essential when using brightening actives.

Why we love it

Most brightening serums pick one or two actives and lead with them. The NUMBUZIN No.5+ Glutathione Vitamin Concentrated Serum takes a different approach — stacking nearly every clinically recognized brightening pathway into one concentrated formula and dosing each active at meaningful levels. Niacinamide at 50,000ppm. Tranexamic acid at 40,000ppm. Panthenol at 50,000ppm. These aren't trace amounts — they're clinical concentrations that reflect NUMBUZIN's commitment to formulas that actually move the needle. Glutathione anchors the formula by addressing melanin at the enzymatic level — the same mechanism that makes it a gold standard in professional brightening treatments. Stable vitamin C (3-O-ethyl ascorbic acid) handles the surface oxidative component. Alpha-arbutin and tranexamic acid suppress further pigmentation formation. Adenosine supports elasticity. Coenzyme Q10 and alpha lipoic acid round out the antioxidant defense. Ceramide NP and panthenol ensure the skin stays supported throughout this active-heavy treatment. Clinically proven to show improvement within two weeks, hypoallergenic-tested, and gentle enough for sensitive skin — this is what NUMBUZIN's No.5 designation delivers for those taking hyperpigmentation and uneven tone seriously in their Korean skincare routine. At BestSkincareUSA.com, it's one of the most comprehensively formulated brightening serums we carry.

Key ingredients deeper dive

• Glutathione — enzymatic melanin suppression for systemic brightening — Glutathione is a naturally occurring antioxidant tripeptide that inhibits tyrosinase, the key enzyme in the melanin synthesis pathway, at the cellular level. Unlike surface-only brightening actives, glutathione works deeper to help interrupt the process that creates pigmentation — making it particularly effective for stubborn hyperpigmentation, melasma, and complexion-wide uneven tone in the NUMBUZIN No.5+ Glutathione Vitamin Concentrated Serum.
• Niacinamide at 50,000ppm — high-concentration tone-evening and barrier support — At this clinical concentration, niacinamide actively inhibits melanosome transfer (the process that moves pigment to the surface), reduces the appearance of dark spots and post-blemish marks, refines enlarged pores, and strengthens the skin barrier — complementing glutathione's enzymatic work with a surface-level brightening mechanism validated across Korean skincare brands.
• Tranexamic acid at 40,000ppm — targeted dark spot and pigmentation care — A clinically studied brightening active that interrupts the communication between UV-stressed skin cells and melanocytes, helping reduce the stimulus that triggers excess pigmentation. Particularly effective for UV-induced dark spots and post-inflammatory hyperpigmentation (PIH), tranexamic acid at this concentration is one of the most meaningful dosing decisions in the NUMBUZIN No.5+ Glutathione Vitamin Concentrated Serum.
• 3-O-ethyl ascorbic acid (stable vitamin C) — antioxidant brightening without oxidation instability — A stable, non-irritating form of vitamin C that delivers the brightening and free-radical defense of ascorbic acid without the degradation issues of pure vitamin C. Helps brighten the overall complexion, fade discoloration, and protect against the environmental oxidative stress that contributes to dullness and pigment formation over time.
• Alpha-arbutin and alpha-bisabolol — supplementary brightening and soothing — Alpha-arbutin provides an additional melanin-inhibiting pathway, complementing glutathione and tranexamic acid for a more thorough anti-pigmentation effect. Alpha-bisabolol (from chamomile) helps calm and soothe the skin alongside this multi-active formula, reducing potential sensitivity from the combined brightening actives.
• Coenzyme Q10 (ubiquinone) and alpha lipoic acid (thioctic acid) — antioxidant firming and anti-aging support — Two of the most potent antioxidant actives in skincare work together here: Coenzyme Q10 supports cellular energy production and helps reduce the appearance of fine lines, while alpha lipoic acid provides broad-spectrum antioxidant defense and supports skin texture. Together they give the NUMBUZIN No.5+ Glutathione Vitamin Concentrated Serum meaningful anti-aging credentials alongside its brightening focus.
• Panthenol (50,000ppm) and ceramide NP — soothing hydration and barrier protection — With panthenol at the same high concentration as niacinamide, the formula ensures the skin remains hydrated, soothed, and comfortable throughout this concentrated active treatment. Ceramide NP reinforces the lipid barrier to protect against moisture loss, making the serum suitable for daily use by sensitive skin types despite its active-heavy composition.

Who it's for

The NUMBUZIN No.5+ Glutathione Vitamin Concentrated Serum is designed for all skin types — particularly those dealing with hyperpigmentation, melasma, UV-induced dark spots, post-acne marks (PIH), or a generally dull and uneven complexion that hasn't responded to lighter brightening treatments. It's especially well-suited for anyone who wants a single concentrated brightening serum that covers multiple pigmentation pathways simultaneously, for those who have tried individual brightening actives (niacinamide-only or vitamin C-only serums) without achieving the results they need, and for anyone building a result-driven Korean face routine around visible pigmentation improvement. Hypoallergenic-tested and suitable for sensitive and acne-prone skin.

Pro tips and pairings

For targeted spot care, apply an extra drop of the NUMBUZIN No.5+ Glutathione Vitamin Concentrated Serum directly to areas of most concern — dark spots, post-blemish marks, or areas of discoloration — and tap gently to concentrate the brightening actives where they're needed most. Daily SPF is non-negotiable when using this serum: brightening actives work to fade existing pigmentation, but UV exposure without sunscreen will continue triggering new melanin formation and undo the progress. Pair with the NUMBUZIN No.3 Radiance Glowing Jumbo Essence Pads as a brightening prep step — the ferment-rich essence pads prime the skin to absorb the concentrated vitamin serum more effectively, creating a comprehensive NUMBUZIN radiance routine that targets dullness and discoloration from both ends.

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