Psycho

A unique delivery system filled with strange and unknown chemicals of military origin, designed at the orders of General Constantine Chase. It is supposed to increase the combat potential of a soldier.

Fallout, Fallout 2 and Fallout Tactics
Psycho is described as "filled with strange and unknown chemicals, probably of military origin".

Psycho has another beneficial effect not intended by the programmers. When taken, it reduces Intelligence by 3. This can be exploited to boost your skill points. First, raise a skill to the point it needs two skill points to be increased, then level up.

When you level up, take two to reduce your Intelligence greatly. This will correspondingly lower your skills involving Intelligence (Science, Repair, Outdoorsman, Doctor, etc). Now allocate your skill points to the skill you want raised - since the skill's value has been lowered, it will take only one skill point to do so. Then rest for a few hours. When the Psycho wears off, Intelligence will be restored, and the skill will be given a significant boost. This s particularly useful for getting a 121% Science skill to recruit Skynet without taking Mentats or wasting too many skill points.

Fallout 3
Psycho appears to be a form of injected drug, which, considering the large serum canister next to the needle, suggests that large quantities are needed to produce the effects. Psycho is very addictive, only taking 3-4 doses used in rapid succesion to result in addiction. Apparently the evidence of the needle and two additional canisters     attached by wire to the hypodermic needle, seems to give evidence that psycho's chemicals must be mixed instantly and in large amounts before the injection into the body, or the drug is worthless.( One less likely theory put forward is one of the two canisters is a battery and the needle must be electricly charged via the wire as the drug passes through into the system to trigger its effects)

It has been suggested that the way the drug works is to give the soldier a better perception of his/her environment, allowing him/her to target weaker areas of a target than before, Triggering dormant parts of the brain focused on reaction speed and reflexes to give the solider the edge needed to take that killing shot.

Locations
Psycho is very common in the capital wasteland, and sometimes sold secretly by shady merchants. There are around 60 in guaranteed locations.
 * Some can occasionally be found in Sugar's house, southwest of Vault 101
 * Around 3-4 doses can be found in the Super Duper Mart
 * Is frequently found in raider establishments
 * It is sold by Doc Hoff, Cindy Cantelli, Ahzrukhal, Leo Stahl and sometimes by doctors.
 * Three can be stolen from Rivet City's chem shop, A Quick Fix.
 * Four can be stolen from Cantelli's Room in Rivet City.