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Congratulations to Common Heir for completing their second clinical trial with Citruslabs

Eco-conscious, inclusive retinol serum for all skin tones 


Common Heir trialled their eco-friendly retinol topical product on measures of wrinkles and fine lines, firmness, and dark spots.  This was an open-label observational single-group clinical trial which received IRB approval and used self-reported participant outcome methods for data collection. This means that there was one study group (the one that received the intervention); all participants received branded samples of the Common Heir product and had to complete baseline and intervention questionnaires. 

About Common Heir

Clean, green skincare that delivers lasting results

Common Heir prioritizes eco-conscious formulas that are good for you and the planet, without sacrificing performance. Their goal is to be: "the glow-up to your go-to."

The company believes clean, natural skincare products should look and feel good while having minimal impact on the planet. Their ingredients are packed with highly recognized natural ingredients, like Algae-oil and astragalus, in order to give your skin a boost from the greenest sources possible. Their Retinol serum is also specifically designed to accommodate darker skin tones after they saw a gap in the research for retinol products on melanin-rich complexions. 

Common Heir has received rave reviews from clean beauty enthusiasts on their range of skincare and wellness products and decided to keep up the momentum with clinical research through Citruslabs. Their goal is to deliver scientifically informed formulas to their customer base and create claims based on the product's actual performance on real people.

The product

Common Heir created a capsule-based Retinol serum to deliver a gentle, smoothing formula without excessive packaging. 

Common Heir Serum - all ingredients:
  • Isoamyl Laurate: Sugar-beet, sugar-cane, wheat/barley-derived provides silicone-like slip while leaving skin soft and supple

  • Coco-Caprylate/Caprate: Coconut derived emollient for silky application and quick absorption.

  • Caprylic/Capric Triglyceride: Coconut derived emollient that gives our unique jelly-serum texture.

  • Neopentyl Glycol Diheptanoate: Castor and/or vegetable derived material helps reduce dry-down time for a quicker absorption.

  • Polyglyceryl-6 Oleate: Plant-based silicone replacement

  • Castor Oil/IPDI Copolymer: Castor oil blended with a bio-based copolymer for a unique jelly-like texture

  • Squalane: Plant-based oil that our retinoid derivative is suspended in, helps nourish and hydrate skin

  • Carthamus Tinctorius (Safflower) Seed Oil: Moisturizing, plant-derived oil with anti-inflammatory properties, botanical blend component

  • Retinyl Linoleate: Our star ingredient: a gentle retinoid ester that boosts cellular turnover, collagen production, and improves skin clarity and tone.

  • Vitis Vinifera (Grape) Seed Oil: Plant-based oil that aides in moisturization and balancing skin's natural pH, botanical blend component

  • Spilanthes Acmella Flower / Stem / Leaf Extract: Plant-based botanical (common name: paracress) rich in antioxidants to help smooth and protect skin from free radicals

  • Astragalus Membranaceus Root Extract: Plant-based biomolecule extract with studied skin smoothing and refining benefits, botanical blend component

  • Tocopherol (Vitamin E): Vitamin E works as an extra antioxidant boost for skin along with keeping our actives stable and potent

  • Ubiquinone (CoQ10): CoQ10 works as an antioxidant, botanical blend component

  • Laminaria Digitata Extract: Algae extract, a hydrating antioxidant that promotes healthy skin renewal

  • Water: Small amount used to suspend algae extract botanical blend

  • Oryza Sativa (Rice) Bran Oil: "- Helps brighten and soothe skin"

  • Tocopherol Acetate (Vitamin E): An additional for of Vitamin E keeping our actives stable and potent

  • Butylene Glycol: Synthetic material used to keep our actives stable and potent

  • Glycerin: Humectant, helps lock moisture into skin to prevent overydrying

  • Ecklonia Cava Extract: Algae extract, a super-hydrating antioxidant to nourish skin

  • 1,2-Hexandiol: Synthetic preservative to help stabilize formula, used at 0.0001%

Study design

This was a single-arm observational study taking place over twelve weeks. Each evening for the duration of the study, participants applied the serum as follows:

  • Weeks 1: 3x per week (at night)

  • Weeks 2: 4-5x per week (at night)

  • Week 3: 7x per week (at night) for the duration of the study, depending on tolerability.

Participants completed a questionnaire about their skin at baseline and then at weeks three, six, and twelve to provide information about the product's performance and their skin progression. Participants also had photos taken at baseline, week six, and week twelve which were assessed by an independent skin grading expert.

The participants

38 women aged 30-55 took part in the study and had self-reported dark spots, wrinkles, or hyperpigmentation All participants were required to forgo their normal skincare routine in the run-up to the study as well as omit any retinoid use four weeks prior, and exclusion criteria included pre-existing skin conditions like chronic acne or psoriasis, as well as the use of any prescription medication to target skin concerns.


Quantifying Common Heir

This interventional study conducted with Common Heir is a great first step and foundational for their research. It established a baseline for their product's effects and performance. The next step for Common HEir would be to invest in a double-blind placebo-controlled study, the gold standard for clinical research. 

Aims & Objectives: To evaluate the effects of Common Heir's retinol serum capsules on dark spots, wrinkles, hyperpigmentation and overall skin health.

Study design: Interventional and observational.

Methods: A total number of 38 female participants completed the study across twelve weeks, using the retinol serum a few times a week in the evenings on clean skin.  The participants were surveyed using an extensive questionnaire at baseline, week three, week six, and week twelve, and had photos taken of their faces at baseline, week six and week twelve.

Results: Using the Common Heir retinol serum was associated with an overall healthier-looking skin and a reduction in dark spots and wrinkles through participants' self-reported data after the twelve-week study period. Participants also reported increased hydration of the skin and an improvement in the appearance of fine lines.

Conclusion: Common Heir's retinol serum is effective in significantly reducing skin texture and improving the overall appearance of participants' complexions. 


Common Heir provides a sustainable option for smoothing skin without sacrificing performance

This single-group study with 38 women demonstrated the efficacy of Common Heir's retinol serum capsules in calming wrinkles, fine lines and dark spots as well as smoothing and firming the skin overall.

Participants rated the severity of common skin-related complaints before starting the study, at the study midpoint (Week six), and at the conclusion of the study (Week twelve).  Participants rated the severity of skincare complaints on a scale from one (does not experience that complaint) to six (severe). Due to the nature of the data, a repeated-measures ANOVA was used to examine significant reductions in these skincare complaints across the duration of the study.


At twelve weeks, notable participant outcomes were as follows:

94% of study participants reported seeing results in their skin after study completion

88% of study participants saw improvements in fine lines and wrinkles

70% saw a visible improvement in dark spots

82% of study participants reported improvements in hyperpigmentation

100% of study participants felt the serum was easy to incorporate into their daily skincare routine

94% of study participants rated the serum as gentle and non-irritating

Results in skin appearance and health

After the twelve week intervention period, 91% of participants reported that they enjoyed Common Heir’s retinol serum results and would like to keep using it.


Other benefits reported centered around the application experience, which the majority of participants enjoyed. Participants also reported that the product did not cause dryness, irritation or increased sensitivity of the skin. 


It's evident in the data analysis above that there were statistically significant improvements in almost every marker of skin health impacted by the retinol treatment. Common Heir's retinol serum was highly effective in targeting fine lines, wrinkles, crow's feet and dark spots, and still caused some improvement in participants' hyperpigmentation.


Further, the product was overwhelmingly well-received by participants, with 94% stating their eagerness to recommend it to a friend. 


Common Heir successfully met the primary objectives of improving fine lines, wrinkles and dark spots in their trial of an encapsulated retinol serum. Their product was well received by participants and demonstrated notable effects on self-report measures of skin health and appearance. There were also significant improvements in the ratings of participants' skin by the independent expert skin graders.

38 participants applied the Common Heir retinol serum several times a week (depending on sensitivity) after facial cleansing for twelve weeks and completed questionnaires at baseline and at weeks three, six, and twelve during the intervention,  while also taking pictures of their skin at baseline and at weeks six and twelve to assess progress. 

Participant outcomes were measured through self-report data which was then assessed for trends in skin changes and overall experiences with the product. Further analysis was conducted on participants' skin progress photos by expert dermatological assessors. Participants were widely satisfied with the product's performance and results, and the outcome data points to the effectiveness of a retinol serum in improving wrinkles, fine lines, and dark spots as well as the overall health of the skin.

About Citruslabs

Clinical trials for consumer brands 

Citruslabs’ mission is to provide robust, affordable clinical trials for brands. We are setting new standards for creating research-backed product claims for supplements, skincare products, devices, CBD products, health foods, and superfoods.

Citruslabs’ mission is to provide robust, affordable clinical trials for brands. We are setting new standards for creating research-backed product claims for supplements, skincare products, devices, CBD products, health foods and superfoods.

We can do it all

Study design

IRB process

Patient recruitment

Patient adherence 

Data collection

Data analysis

Product claims

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