The Medikit is available in the shop for purchase. You can buy 20 of them for 20 gold.
"High-tech medical package that grants instant health recovery."
When you use the medikit, it instantly restores your health to full. The medicate is unlike most other gadgets, as it does not damage the enemy. It is used most effectively in any situation where you are at low health and you don't have a place to hide to regenerate your health, or you need to keep attacking the enemy.