The concept of a "pill" in ASL is generally expressed by just
fingerspelling the letters "P-I-L-L."
Another sign is to use a "G"-handshape as a classifier to mime
holding a "pill" between the tips of your index finger and thumb.
There is a sign that means "take a pill." It looks as if you are
flicking a pill into your mouth.
PILL: "take a pill" (verb form)


You could do a smaller double movement (repetition) of this sign to change
it from a verb into a noun. Or if you do two or more larger (full
movements) to indicate a process of taking pills (as in describing the
behavior of someone who is always popping pills).
You can learn
American
Sign
Language (ASL) online at American Sign Language University ™
ASL resources by Lifeprint.com © Dr. William Vicars