AHA and Retinoids: Do You Need Sunscreen Indoors?

Q: AHA and Retinoids: Do You Need Sunscreen Indoors?

Hello： To be honest, it's not that serious. <br>Using retinoic acid is similar to exfoliation, and the skin is relatively more prone to sunburn. <br>The intensity of sunlight from lamps is not that strong unless you are very close to them (unless it's a desk lamp or table lamp th

Several questions?

Hello, doctor.
I previously had issues with acne and after seeing a doctor, I started using tretinoin and azelaic acid.
I use sunscreen when going out, but I don't use it indoors or at home.
However, many friends say that when using tretinoin, I should apply sunscreen all day because even indoor lighting can cause the treated areas to darken.
Is this understanding correct? Additionally, can azelaic acid be used during the day, or is it only for nighttime use?

Wai, 20~29 year old female. Ask Date: 2008/10/28

Dr. Huang Ruiyun reply Dermatology

Hello: To be honest, it's not that serious.
Using retinoic acid is similar to exfoliation, and the skin is relatively more prone to sunburn.
The intensity of sunlight from lamps is not that strong unless you are very close to them (unless it's a desk lamp or table lamp that is too close).
Azelaic acid can be used during the day.
Wishing you peace and good health.

Reply Date: 2008/10/28

More Info

When it comes to using AHA (Alpha Hydroxy Acid) and retinoids like tretinoin (commonly referred to as A酸 in Mandarin), understanding the importance of sun protection is crucial, even indoors. The concern about indoor lighting, particularly fluorescent lights, is valid. While these lights emit less UV radiation compared to direct sunlight, they can still contribute to skin damage over time, especially for individuals using photosensitizing agents like AHA and retinoids.

Sunscreen Usage Indoors
The recommendation to use sunscreen indoors stems from the fact that certain types of artificial lighting can emit low levels of UV radiation. Although the intensity is significantly lower than that of direct sunlight, cumulative exposure can still lead to skin issues, particularly for those with sensitive skin or conditions like acne. Therefore, if you are using AHA or retinoids, it is advisable to apply sunscreen even when you are indoors, especially if you are near windows or in well-lit areas.
For those who are particularly concerned about skin darkening or hyperpigmentation, using a broad-spectrum sunscreen with an SPF of at least 30 is recommended. This will help protect against both UVA and UVB rays, which can contribute to skin aging and pigmentation issues.

Timing of AHA and Retinoids
Regarding the use of AHA and retinoids, it is generally recommended to apply these products in the evening. This is because they can increase your skin's sensitivity to sunlight, making it more susceptible to sunburn and damage. Using them at night allows your skin to repair itself without the risk of UV exposure.
However, some formulations of AHA, such as glycolic acid, can be used during the day if followed by adequate sun protection. If you choose to use AHA during the day, ensure that you apply a broad-spectrum sunscreen afterward to mitigate any potential risks associated with UV exposure.

Can You Use Azelaic Acid During the Day?
Azelaic acid (杜鵑花酸) is another effective treatment for acne and hyperpigmentation. Unlike some other acids and retinoids, azelaic acid is generally considered safe for daytime use. It has anti-inflammatory properties and can help reduce redness and irritation, making it suitable for those with sensitive skin. However, it is still essential to follow up with sunscreen, as azelaic acid can also make your skin more sensitive to sunlight.

Conclusion
In summary, while the risk of skin damage from indoor lighting is lower than from direct sunlight, it is still advisable to use sunscreen indoors when using AHA or retinoids. These products can increase your skin's sensitivity, and protecting your skin from all sources of UV radiation is a prudent approach. For daytime use, azelaic acid is a good option, but always remember to apply sunscreen afterward. By incorporating these practices into your skincare routine, you can effectively manage acne and pigmentation issues while minimizing the risk of sun damage.

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