Mechanically different from previous versions of Fallout, Jet slows time instead of granting the user more Action Points.
For users who still want the previous benefits, there is an alternative known as Jet Fuel, which still functions as the previous versions. Some distinctive features of this version of Jet are the effects being more akin to that of Turbo, a chem commonly associated with the Mojave.
The use of Jet boosts the user's reaction speed by seemingly slowing down time around them with minimal effect on their own movement. Additionally, it significantly increases jump distance and maximum firing rate for a total of ten seconds, whereas the effects of Turbo only last for three. The effects, however, become shorter each time it is taken within five minutes of each other.
The negative impact of impatience can be remedied by either waiting to use again, taking Addictol or if one has the caps to see a doctor.
Jet can be sold to Bobby De Luca in Vault 81 for 75 caps each, making this an incredible, if time-consuming, moneymaker; dialogue must be initiated for each transaction. Even with all the required merchant perks, it can only be sold normally for 40 caps (50 base price with 80% limit applied to sale value) to regular vendors.
The item model for Jet was reused for the Addictol chem.
Behind the scenes
The recipe for Jet alludes to the drug being produced with brahmin fertilizer. In Fallout 2, Myron confirmed that Jet fumes were discovered using brahmin that had been fed a contaminated protein extract. In Fallout 4 all fertilizer is identical and can be used to synthesize Jet, for simplicity.
The following is based on unverified behind the scenes information and is speculative and may not be accurate.
When used, colors become more saturated and lights become slightly brighter. This visual effect, combined with the inhaler intake and slow-motion perception, makes the Fallout 4 depiction of Jet similar to the drug Slo-Mo from the 2012 film, Dredd.
End of information based on unverified behind the scenes information.