Household: Preschooler, Epi Pen

Question for Moms Who Must Carry Medications (Like Benadryl or Epi-pen).

My three-year-old son has a couple of food allergies that require us to carry an Epi-Pen and Benadryl with us. I need it to be accessible, so I keep it in my purse or in the diaper bag. The problem is that my son loves Benadryl - it has a good taste - and lately he's been "investigating" the bag that I keep the meds in. The Benadryl has a child-proof top, but still ... I'm afraid one day he'll get it off and drink. I'm also worried he'll get the top of the Epi-Pen off and accidentally inject himself. Anyone have ideas about how to keep...