Irradiated beer is an addictive alcoholic drink which when consumed provides a minor status boost - increasing Charisma and Strength by one while reducing Intelligence by one. Irradiated beer, as the name suggests, is a radioactive variant of beer - presumably produced when normal beer has been exposed to large amounts of radiation for an extended period. Thus, it will also impart 10 units of radiation.
As with most alcoholic item in Fallout: New Vegas, irradiated beer's effects (both positive and negative) are altered by the player's Survival skill. With a Survival skill of 100 the player will receive +3 to Charisma and Strength, -3 to Intelligence, and +30 radiation.
In hardcore mode irradiated beer will increase the player's level of dehydration. This effect is also affected by the Survival skill, ranging from +20 at lower levels to +60 at 100 Survival skill.
Effects of Survival skill
+1 Charisma, -1 Intelligence, +24 Dehydration
+2 Charisma, -2 Intelligence, +44 Dehydration
+1 Charisma, -1 Intelligence, +28 Dehydration
+2 Charisma, -2 Intelligence, +48 Dehydration
+1 Charisma, -1 Intelligence, +32 Dehydration
+2 Charisma, -2 Intelligence, +52 Dehydration
+1 Charisma, -1 Intelligence, +36 Dehydration
+2 Charisma, -2 Intelligence, +56 Dehydration
+2 Charisma, -2 Intelligence, +40 Dehydration
+3 Charisma, -3 Intelligence, +60 Dehydration
Note: radiation levels are not affected by the Survival skill level.
Whiskey Rose is a perk provided while Cass is serving as a Companion in the player's party. With this perk the penalty to Intelligence for consuming any type of alcohol is eliminated, as are the effects of alcohol addiction. However, it will still be considered radioactive, and will apply radiation to the player as normal.
One irradiated beer is located inside a booby-trapped, partially wrecked house west of Mole Rat Ranch, almost due north from Durable Dunn's Sacked Caravan. Though the bottle is initially located on top of the bookcase near the front door, it may be scattered if the nearby frag mine is detonated.
Additionally, one bottle may be found in a refrigerator inside Hell's Motel: its contents are a random assortment of irradiated food items, with only an approximate 29% chance of any one specific item being found inside.