RadAway is an intravenous chemical solution that bonds with radiation particles and passes them through the body's system. It takes some time to work, and is also a potent diuretic.
It cannot be used to keep away from, or resist radiation when entering radioactive areas like it's relative namesake Rad-X, but is instead used for after receiving radiation to purge some of it from the body.
On top of being addictive, it has several adverse effects, most notably headaches, stomach pains, and hair loss.
In Fallout 3, RadAway is no longer addictive. This item looks a bit like a blood pack, except with a short tube and a distinctive orange color. It can be found in almost every medical or science facility and can often be found in first aid boxes that hang on walls or are kept on shelves. It can also be bought from a variety of doctors in the Capital Wasteland. The effectiveness of RadAway is dependant on the player's Medicine skill, meaning that the higher the player's Medicine skill, the more Rads are removed.
RadAway has a dull glow, making it easier to find in the dark, though not as strong a glow as a Nuka-Cola Quantum. There is also a readable label marked "RadAway" written on it. This makes it easier to distinguish from a blood pack.