Understanding Inclusion Criteria in Clinical Trials

Whether it's a collagen supplement, an anti-aging serum, or a probiotic for pets, clinical trials are the gold standard for demonstrating product efficacy. But not just anyone can participate in these studies, researchers rely on carefully defined inclusion criteria to ensure that trials are relevant, ethical, and scientifically sound. 

These criteria serve as the gatekeepers of clinical studies, helping brands make credible claims and giving consumers the confidence that the results truly apply to people (or pets) like them.

What Are Inclusion Criteria in Clinical Trials?

In clinical trials, inclusion criteria are the specific conditions or traits that participants must meet to be eligible for a study. These can range from demographic details (like age and gender) to lifestyle factors (such as diet or physical activity) and health-related conditions (like acne-prone skin or mild joint discomfort).

For example, a study on a natural sleep supplement might require participants aged 30-60 who report difficulty falling asleep at least three nights a week. These parameters ensure the study evaluates the product on the right target audience.

Why Are Inclusion Criteria So Important?

1. Scientific Validity

By ensuring consistency in the participant group, inclusion criteria help produce results that are statistically meaningful and reliable.

2. Regulatory and Marketing Integrity

Well-defined inclusion criteria provide a solid foundation for clinically tested claims, making it easier for brands to stay transparent and compliant.

3. Safety and Ethics

Eligibility criteria protect participants by preventing those who may be at risk from being exposed to a product unnecessarily.

Inclusion Criteria vs. Exclusion Criteria

It’s important to distinguish inclusion criteria from exclusion criteria, which identify traits or conditions that disqualify someone from participating. Used together, they create a tightly controlled study population, reducing the risk of confounding factors that could skew results.

How Inclusion Criteria Impact Product Claims

Clear inclusion criteria allow brands to make specific, supportable claims like “Shown to improve hydration in adults aged 25-45 with dry skin” or “Tested on dogs with mild osteoarthritis.” These targeted claims not only boost consumer confidence but also align with FTC guidelines on truthful marketing.

Customizing Inclusion Criteria for Product Categories

Different product types require different approaches to inclusion criteria:

• Skincare & Cosmetics: Focus on skin type, age, and specific conditions (e.g., hyperpigmentation, fine lines).

• Supplements & Superfoods: Look at dietary habits, age, and wellness goals like energy, immunity, or digestion.

• Pet Products: Tailor criteria based on species, breed, age, and health status (e.g., dogs with sensitive stomachs).

This customization ensures the trial results are both meaningful and marketable for your specific consumer base.

Inclusion Criteria and Consumer Trust

Consumers are increasingly savvy and skeptical about product claims. Highlighting the details of a clinical study, including who participated, builds transparency and trust. For example, “Clinically tested on women aged 40-60 with signs of aging” feels far more credible than a vague “clinically proven” stamp.

This specificity also empowers consumers to choose products that align with their personal needs and demographics.

The Role of Inclusion Criteria in Decentralized Trials

As decentralized clinical trials (DCTs) become more common, inclusion criteria are evolving to accommodate remote participation. Digital screening tools and telehealth platforms now allow researchers to apply complex criteria across broader geographies, opening the door to more diverse, yet still well-defined, participant groups.

This is particularly valuable for wellness and personal care brands aiming to reach a global or multicultural consumer base.

Beyond the Basics: Inclusion Criteria as a Strategic Advantage

Inclusion criteria are more than a regulatory requirement, they’re a strategic tool that can set a brand apart. By defining who your product is designed for and rigorously testing it on that group, you lay the groundwork for powerful, compliant, and authentic marketing. 

Whether you’re launching a new adaptogen blend, a wrinkle-reducing eye cream, or a calming chew for pets, well-crafted inclusion criteria ensure that your product delivers results for the right audience, and that your claims stand up to scrutiny.

Looking to craft the perfect design for you next clinical study? Check out our new study design tool for free and get a personalized recommendation in under 2 minutes!