Can a cream stop light from darkening your skin?

Copied word for word from the study's registry entry, so the wording is the study team's rather than ours.

Inclusion Criteria: 1. Caucasian subjects 2. Male and female participants 3. Aged between 18 and 60 years old 4. Skin phototypes III-IV 5. Average ITA° on the back between 18° and 35° (± 2°) at screening and baseline/inclusion visit 6. Uniform skin color over the eight test zones (difference in ITA° between each zone ≤ 4°) 7. Untanned back (no UV exposure - natural or artificial - during the 2 months prior to inclusion) 8. No scar, spot, tattoo or excess hair on investigational zones 9. Subject having given written informed consent 10. Subjects able to read and understand study documents 11. Subjects with an official domicile 12. Subject covered by health insurance or social security 13. Female subjects of child-bearing potential using a safe method of contraception for at least 3 months prior to and throughout the study Exclusion Criteria: 1. Pregnant, lactating, or planning to become pregnant during the study 2. Planned UV exposure (sunlight or sunbeds) of investigational zones throughout the study 3. Sunbed use or sun exposure of investigational zones within the 3 months prior to inclusion 4. Presence of sunburn (erythema) on the back 5. Dermatological disorders affecting investigational zones (naevi, freckles, excess hair, uneven skin tone, vitiligo, photodermatological problems) 6. History of skin cancer 7. History of abnormal response to sun 8. Presence of recent suntan or photo-test marks (per investigator opinion) 9. History of allergy, hypersensitivity, or serious reaction to any cosmetic product 10. Any concomitant medical condition that may interfere with the study (per investigator opinion) 11. Use of systemic medication for more than 5 consecutive days within the month prior to inclusion (e.g., steroids, antihistamines, antibiotics, vitamin A derivatives, psoralen) 12. Use of depigmenting, whitening or propigmenting topical treatments within the 3 months prior to inclusion 13. Physical treatment including laser or phototherapy (PUVA, IPL, PDT) within the past 6 months on investigational sites 14. Planned intensive sport (\> 5 hours per week) or swimming during the study 15. Participation in another clinical study within 30 days prior to inclusion 16. Deprived of liberty by adjunction or official decision 17. Unable to be contacted by phone in case of emergency