In your options menu, what do you have Primary and Secondary Attack bound to? What sort of Keyboard and Mouse do you use? Are you using Windows, Mac, or Linux? Are you using a Gamepad?
Make sure your Primary Attack key is bound to your left mouse button (shows up as Mouse1) and your Secondary Attack key is bound to your right mouse button (shows up as Mouse2)
Can you please tell us what sort of keyboard and mouse setup you're using? What else do you have connected to your computer (gamepad, headset, etc.)? Which version of Windows/Mac/Linux are you using? Are you on a Laptop?
Can you please make sure the items can be actually used in a controlled setting? By that, can you do the following to make sure you can use medkits/bandages/pills? Those items won't activate unless you're hurt or infected.
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To check if bandages work
Create a server (with maxplayers set to 2) on any level When you're fully loaded in, open up your developer console (enable it in your advanced keyboard options and hit `) Once the console is open, type in "sv_cheats 1" without quotes into the console and hit enter Type in "sv_bleedout_chance_high 1" without quotes into the console and hit enter Type in "give item_bandages" without quotes into the console and hit enter. Look down at the ground and pick up the set of bandages that have spawned under your character. Type in "hurtme 100" into the console and hit enter. You've inflicted damage on yourself and it should deal a 100% chance of bleeding Equip the bandages with your inventory wheel Hit your left mouse button (or whatever button you bound to Primary Attack)
To check if the First Aid Kit works
Create a server (with maxplayers set to 2) on any level When you're fully loaded in, open up your developer console (enable it in your advanced keyboard options and hit `) Once the console is open, type in "sv_cheats 1" without quotes into the console and hit enter Type in "give item_first_aid" without quotes into the console and hit enter. Look down at the ground and pick up the First Aid Kit that has spawned under your character. Type in "hurtme 100" into the console without quotes and hit enter. You've inflicted damage on yourself and it should deal a 100% chance of bleeding Equip the First Aid Kit with your inventory wheel Hit your left mouse button (or whatever button you bound to Primary Attack)
To check if Pills work
Create a server (with maxplayers set to 2) on any level When you're fully loaded in, open up your developer console (enable it in your advanced keyboard options and hit `) Once the console is open, type in "sv_cheats 1" without quotes into the console and hit enter Type in "give item_pills" without quotes into the console and hit enter. Look down at the ground and pick up the set of pills that have spawned under your character. Type "infect" into the developer console without quotes and hit enter. You're now infected. Equip the Pills with your inventory wheel Hit your left mouse button (or whatever button you bound to Primary Attack)