Study Archives


The RxPix Study: Home hair collection for the side and back of head




The RxPix Study: Hair kit instructions for the side and back of head

Thank you for participating in our study! The following instructions explain how to collect your hair samples and mail them back to our study. We will use your hair sample only to measure the amount of medication in your hair.

Please read this entire page before starting.
You can also see a video of these instructions at:

1.  Gather your supplies in a comfortable, private, and well-lit location. You will need a friend to assist you.
Remove the following items from this kit:

  • 2 Ziploc bags, one laabeled "Back of head" and one labeled "Side of head". Each bag contains:
    • 1 piece of aluminum foil
    • 2 white adhesive labels labeled “Hair ends”
    • 2 alcohol swabs
    • 1 small freshness packet used to keep your hair samples dry during mailing (leave these inside the Ziploc bags)
  • 1 pre-stamped and addressed envelope you will use to mail your hair back to our study

In addition, you will need:

  • 1 pair of scissors (small if possible)
  • 1 mirror
  • 1 hair clip (if you have long hair)
  • 1 pen or marker

2.  Clean the blades of your scissors. Use an alcohol swab to clean the blades of your scissors and allow them to dry completely.

3.  Prepare a section of your hair from the back region of your head.

  • Ask your friend to assist you.
  • Lift up a top layer of hair from the back of your head. Use a hair clip to keep the top layer of hair out of the way if you have longer hair. 
  • Grab a small lock of hair from underneath this top layer. You will need 30-40 strands of hair.

4.  Cut your hair sample as close to the scalp as possible and place it on one of the pieces of aluminum foil.

  • Cut the lock of hair as close to your scalp as possible (slide the scissors right up to your scalp).
  • If your hair is very short, allow it to fall directly onto the foil.
  • If your hair is long enough, place one of the “Hair ends” adhesive labels over the end furthest away from the scalp, taping it to the foil.

Short hair: Can let hair fall directly into the piece of foil (no need to use labels)


Medium length hair


Braided hair: Cut hair sample from between braids or dreadlocks


5.  Fold over the foil to cover your hair sample and place it back inside the Ziploc bag labeled "Back of Head".

6.  Label the Ziploc bag with today’s date and prepare for mailing. 

  • On the label attached to the outside of the Ziploc bag, fill in today’s date. 
  • Make sure the freshness packet is still inside the Ziploc bag. Close the Ziploc bag and place it inside the pre-stamped envelope addressed back to our study.

7.  Clean the blades of your scissors again. Before cutting your next hair sample, clean the blades of your scissors again. Make sure there is not any leftover hair caught in your scissors, and allow them to dry completely.

8.  Cut another hair sample, this time from the side region of your head.

  • You can cut this sample yourself without your friend's help.
  • Repeat steps 3 - 6, this time cutting your hair samples from the side of your head.
  • Place this foil inside the Ziploc bag labeled "Side of Head".
  • Label this Ziploc bag with today's date and add it into the pre-stamped envelope.

9.  Mail your hair sample. Seal the envelope by removing the adhesive strip, and drop the envelope in any USPS mailbox.

You are all done! If you have any questions, please feel free to contact Kristin at
(415) 638-2563 or [email protected]