The pocket will securely hold the pills depending on their size. If the pill is too small there is a slight chance it could come out, but it is unlikely.
To increase the likelihood that does not happen, pocket contents can be placed inside 1 inch wide x 2 inch long plastic baggies. The bag will hold several pills and also make them water-proof. When pills or other small particles are put are in these baggies and inserted in the pocket, it is nearly impossible for them to fall out on their own. For legal reasons however, PocketBands does not claim to be able to 100% fault-proof as a means of transporting or storing medication.
Here is where you can buy the baggies > http://www.ebay.com/itm/Reclosable-2x1-inch-Plastic-zippy-bags-100-count-Clear-/350692623363?pt=LH_DefaultDomain_0&hash=item51a6e8c403
This size will also work > http://www.ebay.com/itm/ZipLock-Recloseable-Bags-1-x-1-1-2-Clear-100-ct-/281076588624?pt=LH_DefaultDomain_0&hash=item4171786050