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What's a Crossover Study? Exploring its Role in Skincare and Supplement Clinical Trials

supplements and skincare products

Clinical trials are essential tools in the development of new skincare products and dietary supplements. In the health & wellness world, they help to establish efficacy before these products reach the consumer. Among the various designs of clinical trials, the crossover study is particularly noteworthy for its unique structure and effectiveness. In this blog post we will explore what a crossover study is and how it is used in both skincare and supplement clinical trials.

Understanding Crossover Studies

First things first, crossover studies are part of the randomized control trial (RCT) family. This study design is considered the gold standard of clinical trials. Crossover studies can be blinded (where neither participants nor researchers know which product is which), or can be open-label (where researchers and study participants know what product they're using).

A crossover study is a type of clinical trial where participants are sequentially switched between two or more treatment regimens. This means that each participant receives multiple treatments or interventions over different periods, separated by washout periods. These washout periods are crucial as they allow time for any effects of the first treatment to wear off before the next treatment phase begins.

The primary advantage of this design is that it allows each participant to serve as their own control, which can significantly reduce the variability caused by differences between individuals. This design can provide more robust data and reduce the number of participants needed, which is why this study design is often more cost-efficient. You're essentially getting a randomized control trial (such as a double-blind placebo-controlled study) but with only one study group.

Application in Supplement Clinical Trials

For studies researching dietary supplements, crossover studies can be instrumental in evaluating the efficacy of new formulations on health markers such as blood pressure, cholesterol levels, or nutrient absorption. Participants might receive a supplement in one phase and a placebo in another, or two different doses of the supplement across separate phases.

This method is particularly advantageous when studying supplements because it accounts for the natural biological variability in how individuals absorb and react to nutrients. By using the same subjects to compare different conditions, crossover studies can more accurately determine the impact of the supplement compared to other trial designs.

Application in Skincare Clinical Trials

In skincare clinical trials, crossover studies are particularly useful for testing the effects of different products or treatments on skin conditions such as hydration, elasticity, and the appearance of wrinkles. For example, a study might compare the efficacy of two moisturizers. Each participant uses one moisturizer for a set period, followed by a washout phase, and then switches to the second moisturizer.

This trial design is beneficial in skincare because it allows researchers to directly compare how different formulas affect the same individual’s skin. It eliminates many external variability factors such as age, skin type, and environmental influences, providing a clearer picture of the product's true effects.


While crossover studies offer significant benefits, they also come with challenges. The design requires strict adherence to protocols to ensure that washout periods are adequate for eliminating any carryover effects before the next phase begins. This is particularly critical in skincare trials, where the effects of products might linger beyond the treatment period.

Additionally, the complexity of managing multiple treatment phases can increase the risk of non-compliance among participants, which can affect the reliability of the data. Ensuring participant commitment and clear communication throughout the study is essential for its success.

Crossover studies often take longer than two-arm studies, as participants use the product subsequently. If you are on a time crunch and need your results fast, this study design might not be the right one for you.

Everything considered, crossover studies are a powerful tool in clinical trials, especially for skincare and supplement research. By allowing each participant to go through multiple treatments, these studies can minimize external variations, provide more accurate information about a product's efficacy, and are often more cost-efficient than a double-blind placebo-controlled trial. When conducted properly, crossover trials can significantly enhance our understanding of how different treatments work in diverse populations, leading to better products and healthier outcomes for consumers.

This trial design not only optimizes resource use but also enhances the scientific rigor of product testing. Whether in skincare or dietary supplements, crossover studies help pave the way for innovations that can be confidently recommended to consumers, backed by solid evidence of their benefits.

Want to conduct a crossover study for your product? Contact Citruslabs HERE, and we're happy to set up a call to discuss your study goals and evaluate if a crossover study is right for you.


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