X-111 compound

X-111 compound is a consumable item in Fallout 4.

Gameplay
The X-111 compound is an anti-radiation medicine created by Senior Scribe Neriah on the Prydwen.

The player character must give Senior Scribe Neriah 20+ blood samples in the unmarked quest Blood Bank, and then talk to her again. She will give the player character six X-111 compounds and will inform them that if they want more they need to bring her more Viable Blood Samples.

Locations
Six are given by Neriah after giving her 20 Viable Blood Samples. Neriah will take all samples from the Sole Survivor's inventory and pay 50 caps each. Speaking to her again and choosing X-111 will award six X-111 compounds if 20+ Viable Blood Samples have been turned in since the last time. To maximize the amount of X-111, drop or store all but 20 of the samples before speaking to Neriah.