Bleak Venom

The  is a consumable item in Fallout: New Vegas.

Bleak Venom is a lethal hemotoxin that causes considerable damage to a target, dealing 150 damage to it over 10 seconds. Like all venoms, it can be applied to any melee weapon (including thrown weapons) to allow you to envenom a target on a successful hit. Note that one dose of poison lasts for one strike or thrown projectile only. Bleak Venom is the most deadly of the Poisons available in terms of raw damage, making it extremely useful for dealing with high-level and heavily-armored foes as well as those regenerating hitpoints due to radiation or some other effect.

Tribal Pack
The Tribal Pack comes with five doses of Bleak Venom.

Creations
This item is also made at campfires. It requires: Bark Scorpion Poison Gland (3), Cazador Poison Gland (1), and White horsenettle (5). Each successful Bleak Venom crafting yields 3 doses.

It requires a survival skill of 50.