This item can be found when causing a Blood Donation Machine to explode by donating Hearts to it.
This effect is counted as inflicted damage for items that spawn pickups upon said inflicted damage, such as Gimpy or Fanny Pack, but does not decrease the chance of encountering the Devil Room / Angel Room.
Can be used before taking damage (getting hit, walking over spikes, going through a Curse Room, etc.) to grant coins without inflicting extra damage.
Book of Virtues: Spawns wisps in the outer ring, resembling coins. The wisps only have one health.
Cracked Dice: Rerolling the coins generated by IV bag can be used to generate unlimited pickups and items.
Old Bandage + Humbleing Bundle/Maggy's Bow: The damage from IV Bag has a chance to spawn 2 hearts, which can be picked up to create further coins and possibly even heal hearts with enough Luck.
Humbleing Bundle only has a 50% chance to double the hearts dropped, but Old Bandage may still drop 1 heart.
Isaac's Heart: Can be used without taking damage, resulting in an infinite amount of coins.
Isaac still takes damage from this during The Guardian (challenge #30).
Increases each payout to 2-3 coins on Normal mode and 2 on Hard mode.
Portable Slot: Can be alternated between to gain ridiculous amounts of pickups from only a few initial coins or hearts.
Scapular: Allows for infinite coins once Isaac is at half a red heart (or full red heart in Chapter 4 onward) by moving between rooms to reset Scapular's effect.
Bloody Penny: Can chain to create a large amount of coins.
The icon of IV Bag as seen on the lower 3DS screen.
Trivia
A glitch in the original The Binding of Isaac existed where the player could leave a room and activate the item during the invincibility frames offered during recovery of using the items, effectively spawning infinite coins.
Each use pays out with 1-2 coins.
Each use pays out with 1-2 coins on Normal mode or 1 coin on Hard mode.
Spawns 0-1 coins instead when used by 
Keeper.
Red Hearts before other heart types.
Blood Donation Machine to explode by donating Hearts to it.
Gimpy or 
Fanny Pack, but does not decrease the chance of encountering the 
Devil Room / 
Angel Room.
Curse Room, etc.) to grant coins without inflicting extra damage.
Devil Beggar.
The Lost will kill him.
The Book of Belial + 
Birthright as 
Judas / 
Dark Judas: Gives a temporary +0.66 damage up with each use.
Book of Virtues: Spawns wisps in the outer ring, resembling coins. The wisps only have one health.
Cracked Dice: Rerolling the coins generated by IV bag can be used to generate unlimited pickups and items.
Old Bandage + 
Humbleing Bundle/
Maggy's Bow: The damage from IV Bag has a chance to spawn 2 hearts, which can be picked up to create further coins and possibly even heal hearts with enough Luck.
Isaac's Heart: Can be used without taking damage, resulting in an infinite amount of coins.
PHD:
Portable Slot: Can be alternated between to gain ridiculous amounts of pickups from only a few initial coins or hearts.
Scapular: Allows for infinite coins once Isaac is at half a red heart (or full red heart in Chapter 4 onward) by moving between rooms to reset Scapular's effect.
Bloody Penny: Can chain to create a large amount of coins.
Car Battery: No effect.
Holy Mantle and similar items: IV Bag ignores the shield's protection, resulting in Isaac taking damage regardless.
The Binding of Isaac: Rebirth
