Item: The Parasite

Grants Isaac one red heart container and fully restores Isaac's health.

Adds a chance to fire a booger which sticks to enemies and poisons them.

Increases all stats.

Increases damage. Adds a chance to fire acidic tears which can destroy obstacles.

Combined with Key Piece 2, unlocks the golden gate in the starting room of The Chest and Dark Room to fight Mega Satan.

Spawns a flying familiar that bounces around the room with a black aura, dealing rapid damage to any enemies inside it. While standing in the aura, Isaac gains a 1.5x tear damage multiplier.

Grants a soul heart. Adds a chance to block enemy shots.

A familiar that charges forward and deals touch damage to any enemies in its path.

A trail of blue creep is left behind Isaac, which damages enemies.

Isaac gains a shield that protects him from enemy shots.

Grants flight and one eternal heart.

When Isaac is hit, 1 point of an item's charge is filled.

Adds one heart container and drops a random trinket.

Grants flaming tears that deal burning damage over time. Tears have a chance to explode on impact with an enemy, which creates a fire at the location of the explosion.

Spawns a familiar that follows Isaac around and fires two tears at once in a V-pattern.

Spawns a familiar that follows Isaac around and fires slowing tears, impeding enemies' speed.

A familiar who will drop a half red heart every 2 rooms.

Grants flight.

A Devil Room / Angel Room Door will always spawn after every boss fight, excluding the first floor and floors after Utero II/Womb II.

Gives Isaac a random tear effect every room.
Removed in Afterbirth: The effect given changes upon entering a room.
Added in Afterbirth: The effect changes every 3 seconds.