How much if any affect does high summer temps and or humidity and extreme cold temps in the winter have of MED kit items.

I tossed in on a nice kit and don't want to nuke it but doesn't do much good sitting in my house either

I think  you just have to keep an eye on the contents.  We are in an oven most of the summer here.  Seems like most of my tape and combine wraps last about 2 yrs before they go south.  I am not too worried about the little Triple Antibiotic and such.  It melts and rehardens.  Probably does shorten the expiration date on the aspirin/Tylenol/ ibuprofen, but again, personally I don't sweat it.  I don't know if it has any affect on Israeli bandages and such.  

Doc

My med bag stays in the truck. Day time temps of 105-115 in a parking lot means the interior of the truck is much, much hotter than that, even with a windshield reflector and the windows cracked. I check my bag regularly, but nothing- CAT TQ's, Israeli bandages, BVM, bandages, sponges, airway adjuncts, and so on- seems to have degraded. Pens and Sharpies don't hold up well, though. When I lived in MI, the same bag would be exposed to 0*F regularly. Again, no issues. Humidity doesn't have much of an appreciable effect on the components.

EPI pens have a 50-90 or so temp range.  I wouldn't worry about otc pills.  Gloves can get dried out in the heat.

Good thats what I was looking for. Thanks!

Happy to help.

AHSGA's info on the epi pen is good. Check the temp range of any liquids in your kit in particular.