for females ages 18 years and up (full criteria)
at Sacramento, California
study started
completion around



The purpose of this study is to analyze facial pigmentation and skin microbiome changes after topical almond oil application, compared to the use of topical hydroquinone.

Official Title

Prospective Evaluation of Topical Almond Oil vs Hydroquinone on the Appearance of Facial Pigmentation and the Stability of the Microbiome


The purpose of this experiment is to analyze facial pigmentation and skin microbiome changes after topical almond oil application, compared to the use of topical hydroquinone.

There will be a total of 50 subjects:

  • 25 randomized to receive almond oil nightly
  • 25 randomized to receive 2% hydroquinone nightly

Study Timelines:

  • The duration of an individual subject's participation will last from the day of the consent/screening (visit 1) until visit 5 where they will have images taken and measurements collected to assess skin pigment, skin hydration, sebum excretion rate.
  • The duration of participation is 4 months.
  • The estimated time for the investigators to complete primary analysis is 2 years.


Skin Pigmentation, Hydroquinone, Almond Oil, Hydroquinone Topical


You can join if…

Open to females ages 18 years and up

- Premenopausal women of Fitzpatrick skin types 3 to 6

You CAN'T join if...

  • Those with a nut allergy
  • Smoking is an independent risk factor and serves as a confounder for the development of facial aging [18]. Therefore current smokers, those that have smoked within the past year, and former smokers with greater than a 20 pack year history of smoking will be excluded.
  • Those with an autoimmune photosensitive condition or a known genetic condition with a deficiency in collagen production (such as Ehlers-Danlos syndrome) will be excluded as this can be a confounder for facial photoaging.
  • Hormonal medications or therapies will not be allowed unless they have been stable on their medications for at least 2 months. Examples include oral contraceptives, progesterone-based injections, and estrogen based hormonal replacement therapy.
  • Those who have undergone any cosmetic procedures to the face in the 4 months prior to enrollment in the opinion of the investigator. People that have undergone deeper chemical peels (TCA based peels) within 1 year prior to enrollment will also not be eligible.
  • Individuals who are unwilling to discontinue vitamin E containing supplements and food sources during the washout and intervention.
  • Individual who are unwilling to discontinue topical cosmetic products during the duration of the study.
  • Individuals who are not willing to engage in a two-week washout on topical treatments known to affect facial pigmentation and these agents will be restricted during the study period as well. These include topicals that contain:
    • Retinoids such as tretinoin, adapalene, retinol.
    • Antioxidant ingredients such as vitamin C or vitamin E.
    • Pigment-reducing agents such as hydroquinone, azelaic acid, kojic acid per the discretion of the investigator except for the hydroquinone that is provided in this study.
    • Topicals that contain a nut oil or nut extract as part of their ingredient list.
  • Furthermore, subjects will be asked to refrain from use of any other topical products for one week prior to each visit apart from the study agents supplied from this study.


  • UC Davis Department of Dermatology, Clinical Trials Unit
    Sacramento California 95816 United States


accepting new patients
Start Date
Completion Date
University of California, Davis
Learn more or sign up for the study here! Sign up for this study
Phase 4 Skin Pigmentation Research Study
Study Type
Expecting 50 study participants
Last Updated