Wirelessly posted (BlackBerry8830/4.5.0.138 Profile/MIDP-2.0 Configuration/CLDC-1.1 VendorID/105)

I've taken poison ivy lotion in WMD-size bottles on occasion and declared them as medicine. The clerks seem more annoyed than anything. They might look at it like they know what they are looking at. They might swab the bottle or something.
But, stick to your guns if they try to confiscate it. Be prepared to elevate and play the practicing medicine without a license card if necessary.