{"id":6651,"date":"2023-04-27T15:32:14","date_gmt":"2023-04-27T13:32:14","guid":{"rendered":"https:\/\/www.beautydecoded.com\/?page_id=6651"},"modified":"2026-05-30T23:08:10","modified_gmt":"2026-05-30T21:08:10","slug":"serum-vitaminec-conseils","status":"publish","type":"page","link":"https:\/\/www.beautydecoded.com\/en\/vitamin-c\/serum-vitaminec-conseils\/","title":{"rendered":"How to use a vitamin C serum like a pro!"},"content":{"rendered":"<div class=\"bd-brand\"><style>\n.bd-brand .bd-hub-grid{display:grid;grid-template-columns:repeat(auto-fill,minmax(260px,1fr));gap:16px;margin-top:8px}\n.bd-brand .bd-hub-card{display:flex;flex-direction:column;gap:8px;padding:24px 26px;background:rgba(255,255,255,0.6);border:1px solid rgba(255,255,255,0.95);border-radius:22px;backdrop-filter:blur(20px);text-decoration:none;transition:transform 0.25s ease,box-shadow 0.25s ease;box-shadow:0 10px 40px rgba(42,36,56,0.04)}\n.bd-brand .bd-hub-card:hover{transform:translateY(-4px);box-shadow:0 22px 55px rgba(42,36,56,0.1)}\n.bd-brand .bd-hub-card-tag{font-family:var(--bd-sans);font-size:11px;font-weight:600;color:var(--bd-accent);letter-spacing:0.06em;text-transform:uppercase}\n.bd-brand .bd-hub-card h3{font-family:var(--bd-serif);font-weight:500;font-size:20px;line-height:1.2;color:var(--bd-ink);letter-spacing:-0.01em;margin:0}\n.bd-brand .bd-hub-card-arrow{font-family:var(--bd-serif);font-style:italic;font-size:14px;color:var(--bd-accent);margin-top:auto;padding-top:4px}\n.bd-brand .bd-video-wrap{position:relative;width:100%;aspect-ratio:16\/9;border-radius:22px;overflow:hidden;box-shadow:0 22px 55px rgba(42,36,56,0.12);margin-top:8px}\n.bd-brand .bd-video-wrap iframe{position:absolute;inset:0;width:100%;height:100%;border:0}\n.bd-brand>p:empty{display:none!important}\n.bd-brand>p{margin:0!important}\nhtml body .bd-brand .bd-section{padding:48px 0 !important}\nhtml body .bd-brand .bd-hero{padding-bottom:8px !important}\nhtml body .bd-brand .bd-hero .bd-hero-meta{margin-bottom:0 !important}\nhtml body .bd-brand .bd-dark{margin-top:24px !important;margin-bottom:24px !important}\nhtml body .bd-brand .bd-final{padding-top:48px !important;padding-bottom:48px !important;margin-top:0 !important}\n@media (max-width:900px){html body .bd-brand .bd-section{padding:36px 0 !important}html body .bd-brand .bd-hero{padding-top:56px !important}html body .bd-brand .bd-eyebrow{margin-top:8px}}\n<\/style><section class=\"bd-hero\" style=\"padding-bottom:8px !important;padding-top:56px !important\"><div class=\"bd-wrap\"><span class=\"bd-eyebrow\"><a href=\"https:\/\/www.beautydecoded.com\/en\/vitamin-c\/\" style=\"color:inherit;text-decoration:none\">Guide skincare - Vitamin C<\/a><\/span><h1>Vitamin C - <em>why it can stain the skin and how to apply it<\/em> according to a doctor and analyses by BeautyDecoders.<\/h1><p class=\"bd-hero-sub\">If your vitamin C serum colors your skin like a failed self-tanner, it's because it's oxidized: as it breaks down, ascorbic acid produces erythrulose, the molecule in self-tanners, which turns the stratum corneum brown. To avoid this, always apply a skincare product on top (SPF in the morning), put vitamin C at the start of your routine, choose an opaque, airtight bottle, and throw away any serum that has turned yellow-orange.<\/p><div class=\"bd-hero-meta\"><div class=\"bd-hero-meta-item\"><span>Format<\/span><strong>Mechanism + 5 tips<\/strong><\/div><div class=\"bd-hero-meta-item\"><span>Assets<\/span><strong>Vitamin C (ascorbic acid)<\/strong><\/div><div class=\"bd-hero-meta-item\"><span>Approach<\/span><strong>Independent cosmetic analysis<\/strong><\/div><\/div><\/div><\/section><section class=\"bd-section\"><div class=\"bd-wrap\"><span class=\"bd-section-label\">The mechanism<\/span><h2>Why can a serum <em>skin staining<\/em> ?<\/h2><p class=\"bd-lead\">Pure vitamin C (ascorbic acid) is easily oxidized by light and oxygen. To stabilize it, manufacturers add antioxidants, opaque, hermetically sealed bottles, acidic pH formulas and sometimes denatured alcohol to facilitate absorption, at the cost of additional irritation.<\/p><p class=\"bd-lead\">But once on the skin, ascorbic acid is once again exposed to light and air: it can be rapidly denatured. Once oxidized, it undergoes a cascade of chemical reactions. According to a 2011 article on vitamin C degradation products, oxidized ascorbic acid becomes dehydroascorbic acid, then 2,3-diketogulonic acid, which turns into erythrulose. Erythrulose is precisely one of the ingredients in self-tanners: on contact with the skin, it reacts with amino acids in the stratum corneum to form pigments (melanoidins), which color the dead cells of the epidermis until they are naturally shed. Hence those orange or brown areas.<\/p><div class=\"bd-video-wrap\"><iframe src=\"https:\/\/www.youtube.com\/embed\/BenWeF74iKg\" title=\"Vitamin C: why it stains the skin - BeautyDecoded\" loading=\"lazy\" allow=\"accelerometer; autoplay; clipboard-write; encrypted-media; gyroscope; picture-in-picture; web-share\" allowfullscreen><\/iframe><\/div><div class=\"bd-alert bd-alert-info\"><span class=\"bd-alert-icon\">\u2713<\/span><div>Does this mean we should give up vitamin C? Certainly not: it remains an essential anti-aging and anti-dark spot treatment. You just need to follow a few simple rules and know how to recognize an oxidized serum.<\/div><\/div><\/div><\/section><!-- ===== CONSEIL 1 ===== --><section class=\"bd-section\"><div class=\"bd-wrap\"><div class=\"bd-phase-header\"><div class=\"bd-phase-num\">Tip 01<\/div><h3 class=\"bd-phase-title\">Always apply <em>a treatment on top<\/em><\/h3><\/div><p class=\"bd-phase-sub\">Always finish with a sun cream in the morning (or a moisturizer in the evening) after your vitamin C. This prevents contact with the air and protects the skin and vitamin C from UV rays. Wait until the vitamin C is well absorbed before applying the next skin care product: the aim is to avoid oxidation. Once absorbed, vitamin C becomes a formidable antioxidant.<\/p><\/div><\/section><!-- ===== CONSEIL 2 ===== --><section class=\"bd-section\"><div class=\"bd-wrap\"><div class=\"bd-phase-header\"><div class=\"bd-phase-num\">Tip 02<\/div><h3 class=\"bd-phase-title\">Apply vitamin C <em>at the start of the routine<\/em><\/h3><\/div><p class=\"bd-phase-sub\">Apply just after cleansing to enhance absorption, then follow with lighter textures to richer ones (lotion, serum, cream). pH is crucial: a study by Dr Pinnell has shown that it should be below 3.5 for optimum penetration and better stability. The presence of alcohol can improve penetration, and other antioxidants help stabilize the formula, which leads to the next tip.<\/p><\/div><\/section><!-- ===== CONSEIL 3 ===== --><section class=\"bd-section\"><div class=\"bd-wrap\"><div class=\"bd-phase-header\"><div class=\"bd-phase-num\">Advice 03<\/div><h3 class=\"bd-phase-title\">Choose a serum with <em>vitamin E + ferulic acid<\/em><\/h3><\/div><p class=\"bd-phase-sub\">Prefer serums combining other antioxidants. The best combination is vitamin C + vitamin E + ferulic acid: the antioxidant activity of ascorbic acid is multiplied in synergy with vitamin E. Together, they limit the damage caused by exposure to the sun, provided sun protection is always used. For examples of well-formulated serums, see the selection of <a href=\"https:\/\/www.beautydecoded.com\/en\/vitamin-c\/best-serum\/\">best vitamin C serums<\/a>.<\/p><div class=\"bd-alert bd-alert-info\"><span class=\"bd-alert-icon\">\u26a0<\/span><div>A more stable alternative is vitamin C powder, which you mix yourself at the time of use. For deep anti-aging action, mix with an acidic product (a BHA or AHA exfoliant), as a pH-neutral carrier will only provide action on blemishes and radiance. Finally, be wary of silicone-rich serums: they often have insufficient pH, compensated for by alcohol, and their occlusive properties can hinder the absorption of subsequent skincare products.<\/div><\/div><\/div><\/section><!-- ===== CONSEIL 4 ===== --><section class=\"bd-section\"><div class=\"bd-wrap\"><div class=\"bd-phase-header\"><div class=\"bd-phase-num\">Tip 04<\/div><h3 class=\"bd-phase-title\">Choosing a bottle <em>opaque and hermetic<\/em><\/h3><\/div><p class=\"bd-phase-sub\">Buy your pure vitamin C in an opaque, airtight container, ideally stored in a cool place. It's easy to recognize an oxidized serum: if it takes on a yellow-orange color, it should be discarded. Tip: order your serum online rather than on the shelf, to avoid it having been stored for too long in a warehouse or boutique.<\/p><\/div><\/section><!-- ===== CONSEIL 5 ===== --><section class=\"bd-section\"><div class=\"bd-wrap\"><div class=\"bd-phase-header\"><div class=\"bd-phase-num\">Conseil 05<\/div><h3 class=\"bd-phase-title\">Avoid certain <em>associations<\/em><\/h3><\/div><p class=\"bd-phase-sub\">Some active ingredients do not mix well with pure vitamin C. For the <a href=\"https:\/\/www.beautydecoded.com\/en\/retinol\/\">retinol<\/a>, As retinol is also an irritant, never start with both at the same time: retinol first, then vitamin C once it's well tolerated. You should also avoid using copper peptides at the same time as vitamin C.<\/p><div class=\"bd-alert bd-alert-info\"><span class=\"bd-alert-icon\">\ud83d\udca1<\/span><div>If the face is already stained, don't panic: stop and discard the oxidized serum, then wait around 28 days, the time it takes for a cell renewal cycle. Natural desquamation will eliminate the stained cells. An exfoliant can speed up the process.<\/div><\/div><\/div><\/section><section class=\"bd-section\"><div class=\"bd-wrap\"><span class=\"bd-section-label\">Sensitive skin<\/span><h2>And if you have the <em>sensitive skin<\/em> ?<\/h2><p class=\"bd-lead\">Pure vitamin C isn't for everyone: in the case of sensitive skin or redness, it's best to opt for a derivative. Less potent than pure vitamin C, derivatives have the advantage of being highly stable (no risk of oxidation), water- or fat-soluble, depending on your skin type, and easy to combine with other active ingredients, including retinol. For details and examples, see the page on <a href=\"https:\/\/www.beautydecoded.com\/en\/vitamin-c\/vitamin-c-derivatives\/\">vitamin C derivatives<\/a>.<\/p><\/div><\/section><section class=\"bd-dark\"><div class=\"bd-wrap\"><span class=\"bd-section-label\">Key points to remember<\/span><h2>Reflexes <em>essentials<\/em><\/h2><div class=\"bd-pillars-grid\"><div class=\"bd-pillar\"><div class=\"bd-pillar-num\">01<\/div><h4>Never oxidized serum<\/h4><p>A treatment with oxidized vitamin C gives a poor-quality self-tanning effect. Yellow-orange = garbage.<\/p><\/div><div class=\"bd-pillar\"><div class=\"bd-pillar-num\">02<\/div><h4>Seal over<\/h4><p>Always finish with a sun cream (morning) or moisturizer (evening) after the pure vitamin C.<\/p><\/div><div class=\"bd-pillar\"><div class=\"bd-pillar-num\">03<\/div><h4>Good container, start of routine<\/h4><p>Opaque, hermetically sealed packaging, acid pH formula, apply immediately after cleaning.<\/p><\/div><div class=\"bd-pillar\"><div class=\"bd-pillar-num\">04<\/div><h4>Buy online<\/h4><p>Preferably online, to avoid having your serum stored for too long in a warehouse or boutique.<\/p><\/div><\/div><\/div><\/section><!-- ===== CTA APP (bd-final standard) ===== --><section class=\"bd-final\" style=\"padding-top:48px !important;margin-top:0 !important\"><div class=\"bd-wrap\"><div class=\"bd-final-inner\"><div class=\"bd-section-label\">Further information<\/div><h2>Check your serum formula at <em>vitamin C<\/em>.<\/h2><p>The BeautyDecoded application lets you scan any cosmetic product to visualize its suitability for your skin type and needs, based on INCI analysis.<\/p><div class=\"bd-cta-wrap\" style=\"justify-content: center;\"><a href=\"https:\/\/beautydecoded.go.link\/88eZ2\" class=\"bd-cta\" target=\"_blank\" rel=\"noopener\">Discover BeautyDecoded<\/a><\/div><div class=\"bd-cta-meta\" style=\"margin-top: 16px;\">Application available on iOS and Android<\/div><\/div><\/div><\/section><section class=\"bd-section\"><div class=\"bd-wrap\"><span class=\"bd-section-label\">Frequently asked questions<\/span><h2>Your questions about <em>the application<\/em><\/h2><div class=\"bd-faq-list\"><details class=\"bd-faq-item\"><summary>Why does my vitamin C have orange spots?<\/summary><div class=\"bd-faq-answer\">Because the serum is oxidized. When vitamin C breaks down, it produces erythrulose, the molecule in self-tanners, which reacts with the stratum corneum to form brown pigments. The solution: discard the oxidized (yellow-orange) serum and protect the skin after application.<\/div><\/details><details class=\"bd-faq-item\"><summary>How do I know if my vitamin C serum is still good?<\/summary><div class=\"bd-faq-answer\">Look at its color: a fresh serum is transparent or very slightly tinted. If it turns a dark yellow or orange, it is oxidized and should be discarded. An opaque, airtight bottle, kept in a cool place, prolongs its shelf life.<\/div><\/details><details class=\"bd-faq-item\"><summary>Morning or evening for vitamin C?<\/summary><div class=\"bd-faq-answer\">Preferably in the morning, at the start of the routine and under sun protection, to take advantage of its antioxidant action against UV rays. Evening is also possible, as long as you seal with a moisturizer.<\/div><\/details><details class=\"bd-faq-item\"><summary>How long does it take for the stains to disappear?<\/summary><div class=\"bd-faq-answer\">Approximately 28 days, the time it takes for a cell renewal cycle, once the oxidized serum has been stopped. An exfoliant can accelerate the desquamation of stained cells.<\/div><\/details><\/div><\/div><\/section><section class=\"bd-section\"><div class=\"bd-wrap\"><span class=\"bd-section-label\">Further information<\/span><h2>Others <em>associated guides<\/em><\/h2><div class=\"bd-hub-grid\"><a class=\"bd-hub-card\" href=\"https:\/\/www.beautydecoded.com\/en\/vitamin-c\/\"><span class=\"bd-hub-card-tag\">Ingredient<\/span><h3>The complete guide to vitamin C<\/h3><span class=\"bd-hub-card-arrow\">Read the guide \u2192<\/span><\/a><a class=\"bd-hub-card\" href=\"https:\/\/www.beautydecoded.com\/en\/vitamin-c\/best-serum\/\"><span class=\"bd-hub-card-tag\">Comparison<\/span><h3>The best vitamin C serums<\/h3><span class=\"bd-hub-card-arrow\">Read the guide \u2192<\/span><\/a><a class=\"bd-hub-card\" href=\"https:\/\/www.beautydecoded.com\/en\/vitamin-c\/vitamin-c-derivatives\/\"><span class=\"bd-hub-card-tag\">Guide<\/span><h3>Vitamin C derivatives<\/h3><span class=\"bd-hub-card-arrow\">Read the guide \u2192<\/span><\/a><a class=\"bd-hub-card\" href=\"https:\/\/www.beautydecoded.com\/en\/retinol\/\"><span class=\"bd-hub-card-tag\">Ingredient<\/span><h3>Retinol<\/h3><span class=\"bd-hub-card-arrow\">Read the guide \u2192<\/span><\/a><\/div><\/div><\/section><div class=\"bd-sig\"><strong>Dr Sylvain David<\/strong><span>Plastic and aesthetic surgeon - Founder of BeautyDecoded<\/span><\/div><div class=\"bd-disclaimer\"><p>Information for educational purposes only. It does not replace a medical consultation and must be adapted to each individual. Pure vitamin C at low pH can sting reactive skin and oxidizes easily: a yellow-orange serum should be discarded. It should be applied in the morning, at the start of the routine, under sun protection. For sensitive skin, use a derivative. In case of skin pathology or doubt, dermatological advice is recommended. A tolerance test should be carried out before using the product for the first time.<\/p><\/div><\/div>","protected":false},"excerpt":{"rendered":"<p>Skincare Guide - Vitamin C Vitamin C - why it can stain the skin and how to apply it, according to a doctor and BeautyDecoders' analysis. If your vitamin C serum stains your skin like a failed self-tanner, it's because it's been oxidized: as it breaks down, ascorbic acid produces erythrulose, the molecule of...<\/p>","protected":false},"author":120,"featured_media":0,"parent":331,"menu_order":0,"comment_status":"closed","ping_status":"closed","template":"","meta":{"_acf_changed":false,"_kad_blocks_custom_css":"","_kad_blocks_head_custom_js":"","_kad_blocks_body_custom_js":"","_kad_blocks_footer_custom_js":"","_kad_post_transparent":"enable","_kad_post_title":"hide","_kad_post_layout":"","_kad_post_sidebar_id":"","_kad_post_content_style":"","_kad_post_vertical_padding":"","_kad_post_feature":"","_kad_post_feature_position":"","_kad_post_header":false,"_kad_post_footer":false,"_kad_post_classname":"","footnotes":""},"class_list":["post-6651","page","type-page","status-publish","hentry"],"acf":[],"taxonomy_info":[],"featured_image_src_large":false,"author_info":{"display_name":"Sylvain David","author_link":"https:\/\/www.beautydecoded.com\/en\/author\/beautydecoded\/"},"comment_info":0,"_links":{"self":[{"href":"https:\/\/www.beautydecoded.com\/en\/wp-json\/wp\/v2\/pages\/6651","targetHints":{"allow":["GET"]}}],"collection":[{"href":"https:\/\/www.beautydecoded.com\/en\/wp-json\/wp\/v2\/pages"}],"about":[{"href":"https:\/\/www.beautydecoded.com\/en\/wp-json\/wp\/v2\/types\/page"}],"author":[{"embeddable":true,"href":"https:\/\/www.beautydecoded.com\/en\/wp-json\/wp\/v2\/users\/120"}],"replies":[{"embeddable":true,"href":"https:\/\/www.beautydecoded.com\/en\/wp-json\/wp\/v2\/comments?post=6651"}],"version-history":[{"count":2,"href":"https:\/\/www.beautydecoded.com\/en\/wp-json\/wp\/v2\/pages\/6651\/revisions"}],"predecessor-version":[{"id":74571,"href":"https:\/\/www.beautydecoded.com\/en\/wp-json\/wp\/v2\/pages\/6651\/revisions\/74571"}],"up":[{"embeddable":true,"href":"https:\/\/www.beautydecoded.com\/en\/wp-json\/wp\/v2\/pages\/331"}],"wp:attachment":[{"href":"https:\/\/www.beautydecoded.com\/en\/wp-json\/wp\/v2\/media?parent=6651"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}