Effets vitamine C imperfections.

Is vitamin C effective for reducing skin blemishes?

Often linked to a radiant complexion, vitamin C may also support skin prone to blemishes. Can it effectively address pimples? This article examines the evidence.

Summary
Published October 28, 2021, updated on July 18, 2025, by Maylis, Chemical Engineer — 9 min read

Is vitamin C effective against acne?

According to the French Society of Dermatology, there are more than 15 million people in France, including 3.3 million over age 15, with acne.

This skin condition is the primary reason for visits to a dermatologist and can cause real distress for the affected person due to its visible nature. The blemishes develop in the pilosebaceous follicles when the sebaceous glands produce sebum that is too thick or too abundant, which blocks the openings. This hyperseborrhea, or dysseborrhea, often stems from a hormonal imbalance. At the same time, faster cell renewal can lead to a buildup of dead cells on the skin surface, contributing to pore blockage. In this oil-rich environment, a bacterium normally present on the skin in small numbers, Cutibacterium acnes, proliferates and releases pro-inflammatory mediators. At that point, they are no longer just blackheads or whiteheads that appear on the skin, but papules or pustules, and in some cases nodules, which are inflammatory lesions.

Regarding vitamin C, in any form, to date there is no clinical study in humans demonstrating that it can target blemishes.

Moreover, this active ingredient does not appear to have sebum-regulating or keratolytic effects, both essential to address pimples and their root causes. That said, the vitamin C may still offer value for skin prone to imperfections. Indeed, several properties of ascorbic acid – its anti-inflammatory, antioxidant, and antibacterial effects – suggest it could have a complementary role in managing pimples.

First, vitamin C has anti-inflammatory properties that may help reduce redness linked to inflammatory lesions. Several studies have shown that ascorbic acid can inhibit the activation of NF-κB, a transcription factor involved in the innate immune response. This factor plays a central role in starting and sustaining inflammation by promoting the production of pro-inflammatory cytokines such as TNF-α and interleukins-1, 6, and 8. By modulating this signaling pathway, vitamin C may prevent the worsening of inflammatory blemishes and thus avoid post-inflammatory erythema, those persistent red marks that appear after inflammatory acne lesions heal.

Another potential benefit of vitamin C in addressing blemishes is its antioxidant properties, which could allow it to protect sebum from oxidation, including squalene, a major sebum component. When exposed to reactive oxygen species (ROS), squalene can undergo peroxidation and form squalene peroxide, a comedogenic and proinflammatory compound. Squalene peroxide stimulates keratinocyte proliferation. This process promotes hyperkeratinization and the accumulation of dead cells on the stratum corneum. By donating an electron, ascorbic acid stabilizes free radicals and prevents squalene oxidation. It then converts into dehydroascorbic acid, stable due to its aromatic cyclic structure.

Le mécanisme antioxydant de la vitamine C.
The antioxidant mechanism of vitamin C.
Source: WATKINS D. et al. Antioxidant and antitumor effects of dietary vitamins A, C, and E. Antioxidants (2023).
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Moreover, although no study to date has demonstrated a direct effect of vitamin C on C. acnes, several studies have highlighted its antibacterial properties against other microorganisms. In a comparative study using the disk diffusion test, researchers evaluated vitamin C activity at different concentrations (5, 10, and 20 mg/mL) against seven bacterial strains and compared it with erythromycin, an antibiotic often used against acne. As a reminder, the disk diffusion test involves placing a disk impregnated with the compound to be tested on a plate containing bacteria to observe whether a zone without growth appears around the disk, indicating an antibacterial effect. The results, presented in the table below, demonstrate a broad-spectrum antibacterial activity of vitamin C. Mechanistically, vitamin C is thought to disrupt bacterial biofilm formation, preventing microorganism growth.

Bacterial strainsErythromycin (5 mg/mL)Vitamin C (5 mg/mL)Vitamin C (10 mg/mL)Vitamin C (20 mg/mL)
B. subtilis18.3 ± 0.39,7 ± 0,913,0 ± 0,619,3 ± 0,3
B. licheniformis18.3 ± 0.315.7 ± 0.720.0 ± 0.6
P. aeruginosa9.7 ± 0.313,3 ± 0,8
E. coli10,3 ± 0,3 18.3 ± 0.3
S. aureus 16,7 ± 0,322,0 ± 0,6
P. mirabilis26,0 ± 0,615,0 ± 0,620,7 ± 0,827.7 ± 0.9
K. pneumoniae14,0 ± 1,018,0 ± 1,021.3 ± 0.9
Comparison of inhibition zones (mm) obtained with three vitamin C concentrations and with erythromycin against seven bacterial strains.
Source: MUMTAZ S. et al. Evaluation of the antibacterial activity of vitamin C against human bacterial pathogens. Brazilian Journal of Biology (2023).

A recent preclinical study explored the potential effect of vitamin C on acne by combining it with a retinoid topical, well-established adapalene. The researchers used a murine acne model induced by testosterone, a method that reproduces certain features of human acne, including inflammation of the sebaceous glands. Five groups were formed: a control group receiving a testosterone injection (group 1), a group treated with unencapsulated adapalene (group 2), a group receiving encapsulated adapalene (group 3), a group treated with a gel combining encapsulated adapalene and vitamin C (group 4), and a healthy control group (group 5). Encapsulation aimed to improve the stability and penetration of active ingredients.

In fact, the gel combining encapsulated adapalene and vitamin C (group 4) proved most effective at reducing inflammation, decreasing lesion size, and restoring normal skin histological architecture. Its effects were greater than those observed with adapalene alone, whether encapsulated or not, suggesting a potential synergistic effect between the two actives. Although this study was conducted in animals and cannot be extrapolated to humans, it supports the idea that vitamin C, thanks to its anti-inflammatory and antioxidant properties, could play a supportive role in managing skin prone to imperfections.

Évaluations histopathologiques après 4 semaines de traitement sur la peau des rats.
Histopathological evaluations after four weeks of treatment on rat skin.
Source: Dubey A. et al. Development and investigation of a vitamin C–enriched adapalene-loaded transfersome gel: a collegial approach to treating acne vulgaris. AAPS PharmSciTech (2020).

If you have acne, an appointment with a dermatologist is essential to receive appropriate care. Skincare products can support treatment but address isolated or occasional blemishes.

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