Do retinol and vitamin C cosmetics really work? What are the precautions?
This answer is a draft. It stays unpublished until legal review and source verification are complete.
Retinol (a vitamin A derivative) and vitamin C derivatives have become standard ingredients in Japan too, sold for "wrinkle improvement", "pores" and "dullness". In 2017 pure retinol was approved in Japan as a quasi-drug (医薬部外品, a Japanese category between cosmetics and medicines) with the claim "improves wrinkles", and interest took off. If you are used to the rules in your home country, note that what may be claimed here is different. We sort out what is recognised and what is expecting too much.
Where the two ingredients stand
| Item | Retinol (vitamin A derivative) | Vitamin C derivatives |
|---|---|---|
| Approved claim in Japan (quasi-drug) | "Improves wrinkles" (approved for pure retinol in 2017; only approved products may state it) | "Suppresses melanin production and prevents dark spots and freckles" (ascorbyl glucoside, magnesium ascorbyl phosphate etc.) |
| Position as a cosmetic | Up to "makes fine lines caused by dryness less noticeable" (if an efficacy test has been done) | Up to "gives the skin firmness and radiance", "refines skin texture" |
| Action (shown in research) | Speeds up epidermal turnover, promotes collagen production in the dermis, regulates sebum | Antioxidant, suppresses melanin production, supports collagen synthesis |
| Irritation | Redness, peeling, dryness (retinoid reaction / A-hannō), most likely in the first 1–4 weeks | Stinging, dryness (more so in more acidic products) |
| Light and heat | Breaks down in light and oxygen. Use at night, in a light-proof container | Oxidises easily (yellow-to-brown discolouration means it has degraded). Derivatives are relatively stable |
| Combinations to avoid | Using at the same time as peels (AHA/BHA), high-concentration vitamin C or other retinoids stacks up irritation | Same. Combining with niacinamide is generally described as fine |
| Pregnancy and breastfeeding | Standard advice is to avoid | Generally described as fine |
| Time before results show | 8–12 weeks or more | 4–12 weeks |
- How to use retinol: night only, in the order cleanse → moisturise → retinol (a grain of rice to a pearl) → cream. Start at 2–3 times a week, then every night if there is no irritation. Apply thinly around the eyes, corners of the mouth and sides of the nose, where irritation is common. If peeling is severe, take a break. SPF 30 or higher during the day — the skin is more vulnerable to UV while using retinol.
- How to use vitamin C: morning or night. In the morning, apply before sunscreen. Products at 10% or higher tend to sting. Use up within 2–3 months of opening.
- Higher concentration does not mean better: retinol has shown results at around 0.1%, and higher concentrations often just add irritation. Japanese cosmetics are restricted from advertising "X% concentration", so the numbers race is mostly about imported products.
- Imported products (tretinoin, high-strength retinol): tretinoin is a prescription drug in Japan, and there are consumer complaints about peeling and pigmentation from products bought by personal import.
- The quasi-drug "improves wrinkles" claim: only approved products may use it. A cosmetic without approval that says "improves wrinkles" is in breach of the Pharmaceuticals and Medical Devices Act (Japan's cosmetics and drugs law).
[Verify] Check the 2017 retinol approval and the vitamin C derivative claims against the Ministry of Health, Labour and Welfare quasi-drug approval records. Times to results are typical values reported in clinical trials.
Misunderstanding 1｜Apply retinol and the wrinkles disappear
The approved claim is "improves wrinkles", which does not mean deep wrinkles disappear. It applies to fine lines at the corners of the eyes, and assumes 12 weeks or more of use.
Misunderstanding 2｜Redness or peeling means it does not suit my skin
The retinoid reaction in the first few weeks happens to many people. Reduce the frequency and watch. But stop if there is marked swelling, itching or stinging.
Misunderstanding 3｜Vitamin C is acidic, so using it in the morning causes sunburn
Vitamin C derivatives are not phototoxic, and morning use is generally described as fine. Sunscreen is still needed separately.
Misunderstanding 4｜Using retinol and a peel together works faster
Stacked irritation breaks down the skin barrier and causes redness and pigmentation instead. Start with one or the other.
Misunderstanding 5｜Personally importing a high-strength product from abroad is better value
Tretinoin is a prescription drug, and dermatitis and pigmentation have been reported from self-directed use. Use an approved Japanese product or see a dermatology clinic (covered by Japanese health insurance).
---
Sources
- Ministry of Health, Labour and Welfare, "Quasi-drug approval information: the claim 'improves wrinkles' (retinol, 2017)" [医薬部外品の承認情報：しわを改善する効能（レチノール、2017年）]
https://www.mhlw.go.jp/
- Japanese Cosmetic Science Society, "Guidelines for evaluating anti-wrinkle products for a new efficacy claim" [新規効能取得のための抗シワ製品評価ガイドライン]
https://www.jcss.jp/
- Japanese Dermatological Association, "Dermatology Q&A: wrinkles and sagging" [皮膚科Q&A：しわ・たるみ]
https://www.dermatol.or.jp/qa/
⚠️ Editorial note: the source URLs above were identified by search. Our working environment cannot reach go.jp domains, so the contents have not been checked against the text. Verify every source before publication and record who checked it and when.
About this article
What we share here are ideas and everyday practices passed down among people living in Japan, together with general information drawn from public sources. They are not official recommendations, and they are not professional instruction. Practices vary between households and regions.
This is general information. Results vary from person to person and depend on your own conditions and surroundings.
Please decide for yourself, using your own judgement, whether any of this suits your situation. We cannot accept responsibility for any damage, loss or injury arising from following this article.
Cosmetics are not medicines and are not meant to diagnose, heal or prevent any condition. If your skin reacts, stop using the product and see a dermatologist.
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