Medical Kit

Medical Kits are a pick-up in Mercenaries 1 and 2, they restore the merc to full health instantly in the first game and restore a large chunk of HP in the second one, this is especially important in Mercenaries 1 where health regeneration only goes up to 20 points of health.

It's possible for enemies to drop some First Aid in 2 on death so potentially if you're low on health being more aggressive could potentially lead to grabbing extra health while in the near-death state. (Where you take significantly less damage initially.)