1
Induction phase
Nine induction patches were applied over approximately three weeks.
Clinically Tested
Independent clinical study
Clinically tested. Dermatologically reviewed.
HELA Hair commissioned a dermatologist-supervised Human Repeat Insult Patch Test to evaluate the skin tolerability and sensitization potential of its tested Black Shade formula.
“Clinically tested (HRIPT) and dermatologically reviewed by Dr David Wrone, ABMS board-certified dermatologist at an independent UK laboratory.”
Dr David Wrone, MD
Principal Investigator & Consulting Dermatologist
106
Healthy volunteers completed the study
50%
Of the panel had self-assessed sensitive skin
9
Repeat induction patches over approximately three weeks
0
Adverse events or adverse reactions reported
Certificate of skin safety
The official study certificate
The final certificate identifies the tested HELA Hair Black Shade formula, outlines the study design and records the Principal Investigator’s signed conclusion.
- PCR Corp study number: HLHRIP1M
- Tested formula: HH-B-2025-V1
- Tested batch/lot: BATCH01
- Study conducted in Manchester, United Kingdom
- Final report issued December 12, 2025
Select the certificate to enlarge it.
Dermatological oversight
ABMS board-certified dermatologistMeet Dr David Wrone
Dr David Wrone served as the study’s Principal Investigator and Consulting Dermatologist. He was responsible for the study design, protocol review, authorization and summary report. He reviewed the study results and concurred with its conclusions.
“Safety evaluation (HRIPT) conducted under the oversight of Dr David Wrone, ABMS board-certified dermatologist.”
Study design
How the HRIPT was conducted
The single-blind, single-center study used repeated occlusive patch applications based on a modified Draize method. The test article was diluted to 8% with deionized water according to the laboratory protocol.
2
Patch exposure
Each induction patch was worn for approximately 47 or 71 hours.
3
Rest period
Participants completed a 14-day rest period after induction.
4
Challenge phase
A 48-hour challenge patch was followed by readings approximately 1 and 48 hours after removal.
Study findings
The results
Barely visible erythematous responses were observed during the induction phase. During the challenge phase, no questionable reactions were observed in any participant who completed the study.
- No adverse events or adverse reactions reported
- No study deviations reported
- Low potential for irritation and sensitization under the study conditions
- 106 of 111 enrolled volunteers completed the study
Official results and conclusion — page 8 of the signed report.
Transparency
What the study means
What the HRIPT evaluated
- Skin irritation potential following controlled patch exposure
- Skin sensitization potential following repeated exposure
- The specific Black Shade formula and batch in the report
What it did not evaluate
- Gray coverage, final color or color longevity
- Hair breakage, shedding or hair loss
- Full-strength application to the hair or scalp
- Other shades or materially different formulas
Verified documentation
Signed and quality assured
The final report was signed by the Principal Investigator, Project Manager and Quality Assurance Associate. PCR Corp’s quality-assurance statement confirms that the report was audited for an accurate description of the methods and presentation of the study data.
Investigator signatures
Signed by Dr David Wrone, the project manager and the quality-assurance associate.
Official study findings
The report’s results page records the participant data, reactions and final conclusion.
Important safety information
Always complete an allergy alert test
Individual reactions remain possible. Hair-color products can cause allergic reactions, and sensitivities can develop over time. Read and follow all product instructions and complete the required allergy alert test before every application, even if you have previously used hair color without experiencing a reaction.
Do not use hair color on eyelashes or eyebrows. Do not apply it to an irritated, sunburned or damaged scalp.
Study scope: This HRIPT evaluated HELA Hair Black Shade (Dye Shampoo), Formula HH-B-2025-V1, Batch/Lot BATCH01, prepared at an 8% dilution under controlled patch-test conditions. Results apply to that tested article under the study conditions and should not automatically be extended to other shades, different batches or materially changed formulas. HRIPT assesses skin tolerability/sensitization; it does not measure product performance. Data on file.
