Advise on where to look for hidden items or medicine?

Haha. This could be interesting. When I was little, my grandmother would hide her jewelry in the pots and pans when she and my grandfather would travel. Melissa Rivers reported that her mother, Joan Rivers, stashed money in Milk Duds boxes when she traveled!

My FIL was being given his medicine but SIL didn’t realize she needed to watch him take it. He some how thought his dog was sick and was giving it to her. The dog was very lathargic for 2 days when he came to stay with us. FIL told me his dog was sick and he’s was giving him medicine. It turned out the dog wasn’t sick until he gave him HIS medicine. Now we make sure he takes it!!!
Nothing surprises me anymore!!!

Tissue boxes, under a layer of tissues. Wrapped in a paper napkin.

Once you discover the hiding places things get easier, since they often use the same place over and over.

It does sound like this person should no longer have access to medicine.

Freezer. Fridge. Bedside drawer. Teapot, milk jug.
Pockets of any jacket or coats.

cwillie  is right. May be they are taking too many???

Look under the mattress. Happened to a friend. Stove, microwave, clothing drawer.

The problem with looking for things is that logic has gone out the window so they could be anywhere. If missing medicine is a problem then it is time to lock it up and supervise when it is given, aside from hiding it they could be taking it inappropriately.