Acid Baby drops a pill every 3 / 7 cleared rooms. The first drop happens after 2 / 6 rooms.
Upon using a pill, all enemies in the room will be poisoned.
The poison lasts for 2 ticks.
The poison lasts for 6 ticks. Enemies also take 10 additional damage.
This item belongs to the Conjoined set. Collecting three items from this set will transform Isaac into a three-faced version of himself.
Notes
Familiars that follow behind Isaac have a certain priority in how close their position is to him over other familiars, with Acid Baby having the lowest priority at 6th / 8th and thus being farther from Isaac than familiars of different priorities.
Synergies
BFFS!: The familiar drops pills in a repeating pattern of 2, 2 then 3 rooms. No damage increase on the poison effect.
Acid Baby drops a pill every 6 cleared rooms.
Vurp!: If Isaac's last used pill is a Vurp! pill and Isaac finds another Vurp! pill afterward, he can infinitely generate Vurp! pills and repeatedly use them for mass poison damage.
3 / 
7 cleared rooms. The first drop happens after 
Conjoined set. Collecting three items from this set will transform Isaac into a three-faced version of himself.
6th / 
8th and thus being farther from Isaac than familiars of different priorities.
BFFS!: The familiar drops pills in a repeating pattern of 2, 2 then 3 rooms. No damage increase on the poison effect.
Second Hand: No effect.
Starter Deck: All pills dropped by Acid Baby will turn into cards.
