Photostable Sunscreen Explained - Benefits, SPF Stability, Tanning & Pigmentation Protection

Did you think only having a strong SPF in your broad spectrum sunscreen is enough to protect your skin? 

Think again. Your sunscreen also needs to be photostable to give you that extra layer of protection. In this article, we will walk you through what photostability in sunscreen means, its benefits, and role in protecting your skin from tanning and pigmentation. 

What is Photostability in Sunscreen? Benefits, SPF Stability, Tanning & Pigmentation Protection 

While SPF steals the spotlight, Photostability does all the heavy lifting. Let us explain..

Did you know, your sunscreen is a photochemical formula that contains active UV filters, active ingredients in sunscreen that break down UV radiation by reflecting or scattering UV rays,  that break down on sun exposure? 

A photostable sunscreen has advanced chemical filters that do not degrade under direct exposure to sun rays, (UVA & UVB) ensuring consistent & efficient long-lasting protection for your skin against tanning and pigmentation. In simple terms, a photostable sunscreen refers to a sunscreen formula that, when exposed to sunlight, It’s UV filters do not degrade quickly under sun exposure- which means, the SPF stability and UV protection is more consistent than normal formulas.

Now, why does this matter? Let’s break it down.

What Photostability means - The Science Simplified 

When you think of this word, “photostability,” think longevity, durability and quite literally, stability. If SPF tells you how much protection you start with, photostability determines how much of that protection stays with you.

 

Photostability refers to a sunscreen's ability to resist photodegradation- the chemical breakdown of UV filters when exposed to sunlight. Some filters lose their effectiveness rather quickly under UV radiation, causing the product to lose it’s efficacy over time. 

 

Photostable sunscreens are formulated to resist photo degradation. This is where chemistry gets interesting! 

 

They are formulated using advanced filters or stabilised combinations that retain their UV- absorbing capacity even after prolonged exposure. They ensure broad spectrum sunscreen coverage against UVB (burning rays) and UVA( ageing and pigmentation). 

 

When a sunscreen is photostable, both its SPF (UVB) protection and UVA-PF (UVA Protection Factor) remain more consistent over time. 

 

When a sunscreen is non-photostable, sunscreen formulas may experience SPF Loss(%) particularly in the UVA range, despite the product being physically present on the skin.  

 

Some unstable UV filters may degrade significantly under prolonged UV exposure, reducing protection over time. However, actual effectiveness depends on formulation and application. (Source PubMed) 

Studies have shown that  the ingredient Avobenzone is unstable and degrades on exposure to sunlight, significantly losing its effectiveness in it’s skin protection properties.  

To meet the standards of photostability, “new gen” filters have now taken over the market  that are changing the game. 

They offer broad spectrum coverage with minimal photodegradation 

1. Zinc Oxide 

2. ⁠Tinosorb M

3. ⁠Tinosorb S (Bemorrizinol) 

Studies show that these new- gen filters act as stabiliser agents and prevent active ingredients from photodegradation (Source: Journal of Applied Pharmaceutical Sciences). 

In the real world, this is key to ensuring broad-spectrum protection for your skin that lasts beyond just initial application! 

How SPF Stability Matters

SPF Stability is assessed under controlled standardised conditions methods in laboratories. 

ISO 24444 is the gold benchmark for SPF, 

while ISO

In vitro method (ISO 24443:2021) is considered the benchmark for UVA & Photostability (Source: Abich Laboratories Canada). 

According to department of Consumer Affairs, 

Photostability measures how well a product retains is SPF and UVA protection post UV Exposure 

To assess Photostability, sunscreen samples are exposed to UV radiation using a solar simulator and then measured for UV absorption.  

Irradiation dose: Photostability is often assessed by exposing the sample to a specific dose of UV radiation. 

Scientists test the sunscreen by hitting it with UV light first and then measuring it (Source: PubMed)

Scientists then compare pre and post irradiation absorbance to see how much UV protection remains post exposure. 

A product is considered photostable if its SPF or UVA Protection factor does not decrease by more than a set percentage (10% loss) after 120 minutes of irradiation. 

Photostable sunscreen shows significant reduction in the absorption of UV rays and retain their protective properties. 

In real world use, this translates to more consistent UV protection during sun exposure, reducing the risk of degradation from the minute you slather on your sunscreen!

Photostable Filters & What they Do

Photostable filters are advanced ingredients in sunscreens that do not degrade upon UV exposure. They maintain their protective properties for a prolonged period of time. These ingredients absorb or reflect(mineral filters) without degradation.

Mineral filters are:

• inherently photostable 

• Excellent UVA+UVB protection 

Modern new chemicals offer

• Lightweight and easy on your skin 

•  broad spectrum protection

Here is a table of ingredients and their properties for your quick reference

In short, to ensure maximum protection, a photostable sunscreen needs the right amount of ingredients, a high enough concentration to balance out the SPF and a formula that does not degrade in the sun.

To understand how new-generation UV filters improve photostability and offer broader spectrum protection, read our detailed guide on how advanced UV filters protect your skin.

 

Does Photostability Reduce Tanning and Pigmentation?

Short answer? Yes. Here is where it gets interesting. 

While UVB causes immediate burning, UVA penetrates deeper into the skin to induce Persistent Pigment Darkening (PPD) and long term tanning. 

Indian skin is more susceptible to Post-Inflammatory  Hyperpigmentation (PIH) and melasma. 

When UV filters are not photostable, they generate free radicals that promote oxidisation in the skin, which contribute to pigmentation. 

Photostable sunscreens help reduce photo-oxidative stress by maintaining consistent UV protection, where sun exposure stimulates the production of melanocytes,sensor cells that capture radiation to produce melanin (Source PubMed).

Also, using broad spectrum photostable ingredients+ UVA-PF reduces cumulative UVA exposure, limiting pigment activation in your skin.

To further protect against visible-light induced pigmentation, especially for melanin-rich skin, tinted sunscreens are highly effective. These formulas contain iron-oxides that reflect visible light, which clear sunscreens miss.

Together, a high UVA-PF+ photostable formulas are your go-to- line of defence for your skin against unwanted tanning and pigmentation. 

Real-World Factors — Texture, White Cast, Reapplication 

You know the science behind it, now let us give you the practical, real-world advice you can actually “apply” when it comes to photostable sunscreens. 

Photostability does not mean permanent protection

.Even the most photostable sunscreen requires reapplication. Despite containing advanced UV filters that do not breakdown easily, their effectiveness degrades over 2 hours since initial application due to your skin’s production of sebum and other environmental factors.

Water/Sweat Resistance may still cause wear and tear. 

Designed for active lifestyles, photostable sunscreens stay effective during swimming for 40-80 minutes. After that reapplication is still necessary. 

Sweat combined with body heat and movement breaks down sunscreen over time. 

Remember to apply sunscreen 15 minutes prior to your outdoor activity so it helps resist sweat better. 

Texture also matters  

• Heavy or greasy formulas like mineral filters (Zinc Oxide) often cause a white-cast due to their reflective properties which is more apparent on deeper skin tones. If you have oily skin texture or acne prone skin, a lightweight gel-based photostable sunscreens are ideal because they offer high long-lasting protection with a non-greasy finish that leaves no white cast. 
  
  

How to Choose Your Photostable Sunscreen 

Here’s a short checklist for you to follow while picking your photostable sunscreen. Ensure you choose one that is perfect for YOUR skin

1. Ensure that the sunscreen offers Broad-Spectrum Protection, ensuring protection against UVA+UVB with  SPF ≥30 /50.  SPF 30 blocks out 97% of UV rays and SPF 50 blocks out 98%. 

2. Check if the label indicates a clear indication of photostable filters (Tinosorb S/M, Uvinul A Plus). 

3. Check for clear mentions of ISO Test References on the sunscreen label (ISO 24443:2021)

4. Aim for a high UVA+PF/ PA rating. Aim for a PA++++ rating or a critical wavelength of 370nm to ensure deep UVA protection 

5. Choose a formula suitable for your skin type: For oily skin, choose lightweight or gel-based formula. For Pigmented skin, choose a tinted sunscreen with iron oxides 

6. Ensure your photostable sunscreen is water resistant if you spend a lot of time outdoors or are engaged in intense activity throughout the day. Look for a sunscreen water-resistant for up to 40-80 minutes to ensure skin protection. 
   

Recommended Photostable Sunscreens 

Here is a list of photostable sunscreens curated for your specific skin type, for your convenience. 

Conclusion:

Photostability means the ability of UV- filters to resist breakdown post UV- exposure. A photostable sunscreen remains it’s protective efficacy even after UV exposure. 

Remember, a photostable sunscreen cannot protect you from reapplication. Even though the process is slowed down significantly, you still need to reapply sunscreen every 2 hours.

Indian skin is highly susceptible to pigmentation and dark spots. Using a photostable sunscreen for your skin that provides long-lasting consistent UVA+UVB protection is crucial in mitigating melasma production resulting in pigmentation.

Explore our range of photostable sunscreens packed with advanced  new-gen filters that offer lightweight, gel-based solutions that do not feel heavy and greasy on your skin, giving you all- round protection. 

Sit back, relax and let us do all the work for you and your skin. 

FAQ 

What does photostable sunscreen mean?

Photostable sunscreen resists breakdown upon UV exposure offering, a longer, consistent protection of your skin against the harsh UV rays.

Will photostable sunscreen stop tanning?

Photostable sunscreen does not stop tanning, but it significantly reduces tanning as they maintain their protective structure for longer, preventing their filters from breaking down quickly. This gives your skin more durable protection against UV exposure

Do photostable sunscreens still need reapplication?

Yes. Photostable sunscreens still require reapplication after 2 hours of initial application. Especially if swimming, sweating or towel drying.