Numbuzin No. 5+ Glutathione C Serum Review | A Thoughtful Choice for Brighter, More Radiant Skin
- Editorial Team
- Jul 22
- 6 min read
Author: Eat Well · Feel Well · Live Well Editorial Team
Visible pores and uneven skin texture are concerns that often become more noticeable with age.
Even when we follow a careful skincare routine, seeing roughness, dullness, or unevenness in the mirror can make us wonder whether there is one more product worth adding. Acne, meanwhile, is especially common during adolescence and early adulthood, and its impact can extend beyond appearance, affecting confidence and emotional well-being. Our editorial team first became interested in Numbuzin No. 5+ Glutathione C Serum while looking for a product that could address the appearance of pores and also be incorporated into a family member’s acne-care routine.
Numbuzin is a Korean skincare brand known for its easy-to-understand numbered product range. Among its products, the No. 5+ line has attracted particular attention from skincare enthusiasts, thanks to its association with ingredients such as glutathione and vitamin C and its focus on achieving a brighter, more even-looking complexion. Popularity, however, does not guarantee the same results for every skin type. Enlarged pores and acne are very different concerns, and even when the same serum is used, the experience and compatibility can vary considerably from person to person.
Rather than relying solely on reputation or marketing claims, we examined the serum’s texture, how it felt when applied, whether it left any stickiness, its fragrance, and how easily it could be incorporated into an everyday skincare routine. We also approached the review with realistic expectations. Instead of asking whether pores would physically shrink or acne would disappear immediately, we focused on whether the serum could help condition the skin and improve the appearance of dullness and visible pores associated with dryness.
Radiance is not something that appears after a single application. It develops through the combined effects of daily cleansing, moisturising, sun protection, sleep, diet, and other consistent habits. Within that broader routine, what role can this serum realistically play? In this review, our editorial team shares its first-hand experience, including not only what we liked, but also the points that gave us pause.
A Multi-Faceted Formula Designed to Support Brighter-Looking Skin
Numbuzin No. 5+ Glutathione C Serum is formulated to address the appearance of dullness, uneven tone, and dryness from several angles, rather than relying on a single hero ingredient.
At the heart of the formula are glutathione, niacinamide, tranexamic acid, and vitamin C—ingredients commonly found in skincare products designed to promote a brighter, more even-looking complexion. These are complemented by moisturising and skin-conditioning ingredients such as panthenol and ceramides, helping the formula support hydration and skin comfort while working towards a clearer, more radiant appearance.
Niacinamide
Niacinamide is known not only for supporting a brighter, more even-looking complexion, but also for helping maintain the skin barrier. This makes it a useful ingredient for skin where pores may appear more noticeable due to dryness.
However, niacinamide does not physically reduce the size of pores. A more accurate way to understand its role is that, by supporting hydration and helping to refine the appearance of skin texture, it may make pores look less prominent.
Tranexamic Acid
Tranexamic acid is commonly used in skincare formulated to help prevent irritation and address the processes involved in melanin production.
Redness or brownish marks left behind after acne may be associated with inflammation or post-inflammatory pigmentation. For this reason, tranexamic acid is best understood not as an ingredient that treats acne itself, but as a supportive ingredient that helps care for post-acne skin and promotes a more even-looking complexion.
Glutathione
Glutathione is a compound made up of three amino acids and is used in skincare formulations for its antioxidant properties.
Vitamin C Derivatives
Vitamin C derivatives are modified forms of vitamin C designed to improve stability and make the ingredient easier to incorporate into cosmetic formulations.
They are widely used to help refine the appearance of skin texture and address multiple concerns, including excess oil, visible pores, post-acne marks, and dullness.
Alpha-Arbutin
Alpha-arbutin is commonly used in brightening skincare for its ability to act on an enzyme involved in melanin production.
Panthenol
Panthenol, also known as provitamin B5, is a moisturising and skin-conditioning ingredient.
Serums designed to target dullness and uneven tone can sometimes feel drying or irritating, depending on their formulation. In this formula, panthenol helps soothe and condition the skin, making the serum easier to incorporate into a daily skincare routine.
Ceramides
Ceramides are naturally present in the skin’s outermost layer and play an important role in retaining moisture. When the skin becomes dry, its texture can appear less refined, making pores and dullness more noticeable.
Replenishing ceramides can help reduce moisture loss and support a smoother, more even-looking complexion. Radiance is influenced not only by brightness, but also by the skin’s hydration levels and surface texture. The inclusion of moisturising ingredients is therefore one of the serum’s key strengths. Ceramides are also commonly used in haircare products.
Rather Than “Whitening” the Skin, This Serum Helps Refine Its Overall Appearance
The purpose of this serum is not simply to make the skin look whiter.
Instead, it is designed to support the skin in several complementary ways:
helping to prevent dullness caused by dryness
refining the appearance of skin texture
making uneven tone appear less noticeable
helping to keep post-acne skin in healthy condition
improving the appearance of pores through hydration
By combining these effects, the formula aims to give the complexion a brighter, smoother, and more even overall appearance.
What We Thought After Trying It
After applying the serum, we gently pressed it into the skin with the palms of our hands. With light, repeated patting, the formula gradually absorbed and any initial tackiness soon became barely noticeable. Its fresh, lightweight texture made it easy to incorporate into an everyday skincare routine.
The serum is not intended for night-time use only and can be applied both morning and evening. When using it in the morning, it is important to follow with sunscreen to protect the skin from UV exposure. Those with sensitive skin may prefer to begin by using it only at night or gradually adjusting the frequency according to how their skin responds.
What We Liked
It felt only minimally sticky, making it easy to use as part of a morning skincare routine.
When applied before makeup, it did not cause foundation to separate or shift easily.
Although the texture felt fresh and lightweight, the skin remained comfortably moisturised.
The added hydration made the complexion appear brighter and more refreshed overall.
Points to Consider
Those expecting immediate results may find the serum underwhelming.
Dark spots and areas of pigmentation are unlikely to change significantly within a short period.
Consistent use as part of a regular skincare routine is essential when evaluating its effects.
Overall Rating
★★★★☆ 4.0／5.0
With its fresh, lightweight texture and minimal stickiness, this serum is easy to incorporate into both morning and evening skincare routines. It absorbs without leaving much residue on the skin, and we particularly appreciated how well it worked before makeup.
That said, changes in the appearance of dark spots, post-acne marks, and pores cannot be properly assessed after only a short period of use. Rather than a serum designed to deliver instant results, it is better suited to consistent use alongside adequate moisturising and daily sun protection, with the aim of gradually supporting a brighter, more even-looking complexion.
Who We Recommend It For
Those concerned about dullness caused by dryness or an uneven-looking skin tone
Those looking to care for and condition post-acne skin
Those seeking a lightweight, non-sticky serum that is easy to use in the morning
Those who want to incorporate several brightening ingredients into a single skincare step
Fans of Korean skincare
Product Details
Brand: numbuzin
Product name: No. 5+ Glutathione Vitamin Concentrated Serum(Japanese product name: No. 5 Glutathione C Concentrated Serum)
Size: 30 mL
Country of origin: South Korea
Prices and availability may vary by country and region. Please check the relevant official website for the latest information.
Editor’s Note
Numbuzin No. 5+ Glutathione C Serum is better suited to those who want to gradually cultivate a brighter, more radiant-looking complexion through consistent daily care than to those seeking immediate results. Its lightweight, non-sticky texture also makes it easy to use both morning and evening. Rather than rushing the process, this is a serum to use consistently alongside adequate moisturising and daily sun protection.
