What are the common misunderstandings about protecting hair from UV?
This answer is a draft. It stays unpublished until legal review and source verification are complete.
Sun protection for the skin is now routine, but hair and scalp are easily forgotten. In Japanese summers you will see hair UV sprays on every drugstore shelf (Matsumoto Kiyoshi, Welcia, etc.), which raises the questions "Does UV really damage hair?" and "Do I need a sunscreen for my hair?" Here we look at how hair behaves and at the approach taken by the Ministry of the Environment's UV manual.
Points to consider
| Item | Detail |
|---|---|
| Effect on hair | UV damages the protein of the cuticle; melanin breaks down and the colour fades (turns reddish-brown); dyed colour fades; dryness and breakage |
| Effect on scalp | Sunburn (inflammation), as on any skin. The parting and the crown burn most easily. Some explanations describe scalp sunburn as one cause of hair loss |
| Most reliable protection | A hat (brim 7 cm or wider) and a parasol (Ministry of the Environment manual). Choose UV-blocking hats by their shading rate |
| Hair UV spray | A cosmetic ("protects the hair", etc.). SPF/PA ratings are standards for skin; there is no measurement standard for protection of hair. A supplement |
| Skin sunscreen on the scalp | Some people apply it along the parting, but it is greasy and hard to wash out. Scalp-specific spray types exist |
| Sea and pool | Chlorine and salt plus UV speed up fading and dryness. Wet hair is more vulnerable to UV. Hat, and rinse with fresh water |
| Washing | On days of UV exposure, moisturise thoroughly (treatment) |
- The Ministry of the Environment's manual names "hat, parasol, clothing, sunscreen, sunglasses" as the basics of UV protection, and lists hats and parasols as the means of protecting the head and eyes. It says little about the hair itself.
- Fading of hair colour is mainly caused by UV and washing (shampoo). Summer colour fades faster is the usual explanation in the hair trade.
- Hair UV spray is a standard Japanese summer product, but use it as a supplement in the knowledge that an SPF figure is "a measurement on skin" and not a figure for protection of hair.
[Verify] Check the relevant passages of the Ministry of the Environment manual, and the effects of UV on hair against standard hair-science texts.
Misunderstanding 1｜UV does not damage hair
Cuticle damage, fading and dryness all happen. Because hair does not regenerate, prevention is what counts.
Misunderstanding 2｜SPF50 hair spray protects hair 50 times over
SPF is a measurement standard for skin, not a figure for protection of hair. A hat and parasol are reliable; spray is a supplement.
Misunderstanding 3｜Black hair is resistant to UV
With more melanin it is "slower to change colour", as with skin tanning, but damage still occurs. Dyed hair fades faster.
Misunderstanding 4｜The hair protects the scalp
The parting, the crown and thinning areas do burn. A hat, or a scalp spray. Redness, itching and peeling are sunburn symptoms.
Misunderstanding 5｜Getting wet in the sea protects against UV
Wet hair lets UV through more easily, and salt or chlorine on top of that is the most damaging combination. A hat, and rinse with fresh water.
---
Sources
- Ministry of the Environment, "UV Environmental Health Manual 2020" [紫外線環境保健マニュアル2020] (hats and parasols)
https://www.env.go.jp/chemi/uv/uv_manual.html
- Japan Cosmetic Industry Association, "SPF Measurement Standard" [SPF測定法基準] (measured on skin)
https://www.jcia.org/user/business/spf
- Japanese Dermatological Association, "Dermatology Q&A: Hair Conditions" [皮膚科Q&A 髪の毛の病気]
https://www.dermatol.or.jp/qa/qa17/index.html
⚠️ 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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