They should be recycleable. Check for a number on the bottom of the bottle. Otherwise, I use them for nails, screws and tacks in my tool box, or safety pins and sewing machine needles in my craft room. Some taller bottles will hold a few crayons for the kids/grandkids for coloring on paper table mats in restaurants. I've also used the good screwtop ones for shampoo/bodywash/lotions when we go out of town for a weekend. Then if I mistakenly leave it there, I'm not out a whole bottle! We went to a corn boil and I put sea salt in one, because I have high blood pressure and can't use regular salt. I'll put salad dressing in them; ketchup, peanut butter and jelly for a lunch, butter, etc. Just be sure they are clean of the meds that were in them. The possiblities are endless!
I use them for my beads if they are clear. They can be used for storage depending on size.
You could donate them to a local animal rescue. They use them to animal medications.
I keep citrus zest or chopped hot pepper in them in the freezer. Also good for spices.
I have used them to mold toddler crayons. Sort and peel paper off broken crayons put them in soup cans placed on cookie sheet , place in oven set on 225 until melted pour in med. bottles until harden. Place in freezer until loose....they last a long time! You can also make rainbow colors. Great way to use those broken crayons! :)