In Vivo Or In Vitro? Unraveling Sunscreen Testing’s Big Debate

With the days longer and the Sun brighter than ever, protecting your skin from heat and sun damage becomes cardinal, and if there’s one product you can’t do without, especially in this season, it’s sunscreen. From hydration to radiant glow and an invisible finish, the current lineup of sunscreens has been designed to cater to your every need with distinctively innovative formulations (like serums, mists, and sunsticks) and active ingredients to offer more than just sun protection. Yes, this summer is going to be bright and protected! And to understand the performance and safety of your sunscreens against harmful UV radiation, let’s dive into the reliability, limits, and effectiveness of sunscreen testing.

In vivo and in vitro aren’t just two words that many of us have seen over the past few days across Instagram – rather, they are established sunscreen testing methods to ensure compliance and safety. The in vivo testing is typically conducted on human volunteers to assess sunscreen efficacy under conditions mimicking real-world use, with sunscreen applied to a defined skin area (often on the back) and exposed to controlled UV light. On the other hand, in vitro testing is conducted on artificial skin models or substrates (like PMMA plates) to measure sunscreen’s UV-blocking properties. While in vivo directly measures SPF (sun protection factor) and is considered a gold standard to determine and reflect the actual sunscreen performance, in vitro is primarily preferred for formulation development and optimization as it’s controlled, cost-effective, and lab-based.

Though considered an ideal marker of SPF, in vivo testing does present a share of ethical concerns over the safety of volunteers against over-exposure and diverse skin-type representation, along with being fairly expensive. And in vitro has been known to overestimate or underestimate sun protection due to substrates lacking skin’s complexity and the absence of dynamic environmental conditions. As Pratik Ved (Vice President – Skincare, Hindustan Unilever Limited) adds, “In vivo testing as per ISO 24444 & ISO 24442 are globally accepted methods for SPF & UVAPF testing, which require rigorous ethical standards. At Lakmē, we ensure all human volunteer testing is conducted at a third-party accredited clinical research organization with informed consent and full risk disclosure under a trained dermatologist’s supervision. The testing is done after approvals from an ethical committee comprising of medical scientists, clinicians, a legal expert, and a social worker, ensuring that the safety of the volunteers is taken care of.”

Furthermore, aligning the two tests ensures a balanced, holistic approach for data accuracy and real-life sunscreen efficacy. And Pratik agrees, asserting that at Lakmē, we harmonize and synergize in vitro and in vivo testing – beginning with lab simulations and then validating our SPF and UVA-PF performance on human volunteers. “This dual approach allows us to minimize gaps, improve formulation accuracy and stability, and ensure our sunscreens are truly effective and safe for everyday use.,” he adds.

Elaborating on the dual testing and making of D’you’s much-loved capsule sunscreen unkissed, Shamika Haldipurkar (Founder, D’you) notes, “When we first launched unkissed, the formula was tested via both in vitro and in vivo. It always starts with in vitro, which gives an indicative range, and then it’s followed by in vivo to lock down on the final claimed SPF value. Usually, there is 20-40% variance in the results of both the tests, which is why a formula is first tested in vitro and then confirmed via in vivo.” For unkissed by D’you, the in vivo test gave an SPF 52-60 result, and in vitro results showed SPF 76.5. Thus, they claimed only SPF 50 on the product when it first launched. And with the new revised formula, the in vitro test results showed an SPF113 (extremely high!), and considering the variance, D’you claims only an SPF 70.

Amidst India’s lack of stricter sunscreen testing protocols (concerning in vivo testing) and in vivo’s cost factor, many sunscreens are tested in vitro using the COLIPA method according to the current guidelines. In such cases, transparency and accountability from brands becomes especially imperative, i.e., if a brand is only doing in vitro testing, then the claimed SPF value should account for the variance in the in vitro result. And then we do have brands (like D’you, Lakmē, Minimalist, and The Derma Co.) that have their sunscreen formulations undergo both in vivo and in vitro testing to ensure complete efficacy. Even in this scenario, prioritizing transparency is equally essential, along with community education via digital content and the publication of results and certifications. “With unkissed or any product of D’you, when we conduct clinical studies, we always publish and showcase those results on our website, and educate the consumer about the product through social media. The right amount of transparency and knowledge always helps a consumer make an informed purchasing decision – and it’s definitely something that our community continues to appreciate.,” Shamika adds. And Dr. Kiran Sethi (Founder – Isya Aesthetics) concurs with the importance of transparency and education, adding, “We need to know what’s going on our skin and body. Therefore, when recommending sunscreens, I look into the sunscreen test results and regulations of the country where the product is made to ensure suitability and compatibility with the patient’s skin and sun care history, and share the same with them.”

With the sunscreen testing protocols still evolving in India, brands, dermatologists, beauty connoisseurs, and media can continue to empower the consumer with transparency and knowledge to foster confidence and trust, and an understanding of sunscreen formulation and its testing mandates. Delving into Lakmē’s #SPF50Truth100 campaign, Pratik says,” Today’s beauty consumer is well-informed and deeply engaged. They want to know the science behind the product, and rightly so. We launched the campaign to spotlight the science, testing, and truth behind our sunscreen formulations – to ensure the consumer that a Lakmé sunscreen is not just effective, but tested with integrity.”

Ahead, scroll through for some of the most effective, reliable, and in vivo-tested sunscreens available in the Indian beauty market.

D’you unkissed Capsule Sunscreen SPF70+ PA++++ (Rs.2,2000) and ISDIN Fotoprotector FusionWater Sunscreen SPF50 UVB/UVA (Rs.2,190)

Lakmē 5% Nia-C Complex Aqua Sun Gel SPF50 PA++++ (Rs.499) and Beauty of Joseon Relief Sunscreen Rice + Probiotics SPF50+ PA++++ (Rs.1,570)

Minimalist Sunscreen (With Niacinamide) SPF50 PA++++ (Rs.399) and Simple Sunscreen Gel SPF50 PA++++ (Rs.399)

The Derma Co. 1% Hyaluronic Sunscreen Aqua Gel SPF50 PA+++ (Rs.499) and SKIN1004 Madagascar Centella Hyalu-Cica Water-Fit Sun Serum SPF50+ PA++++ (Rs.2,399)

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