T Nation

Caffeine Takes 3-4 Hours?


is there any truth to the statement "caffeine takes 3-4 hours to effect the system"?

someone told me they learned it from their physiology class or something.

i said there is no way but i would get to my experts and report back. thanks guys.


I'd be surprised because whenever I take a caffeine supplement I feel it within minutes.

Maybe it's a placebo effect?


No, it happens much faster than that for most people. It'd be more accurate to say it starts having an effect at about 30 minutes (depending a little on digestion rates) and reaches full effect in a couple hours.

It also depends on whether or not you start exercising after ingesting it - if you get blood flowing around faster it'll take effect a bit faster.



3-4 hours to LEAVE the system. If it took 3-4 hours to effect the human body, Red Bull would be out of business and there would be no addiction in this country to "Morning coffee".


And my husband would never get out of bed.


You're referring to caffeine's effects on metabolizing free fatty acids.

The CNS stimulating effects are obviously much quicker.


Maybe you heard that caffeine takes 3 - 4 hours (or more) to be cleared from your system - which is why it's not a great idea to take caffeine in the late afternoon if you're sensitive to it or tend to have trouble sleeping.


The initial response or onset occurs within 15-45 minutes in healthy adults.

Peak plasma concentrations are reached around 30-36 minutes on average.

The elimination half-life is 4-5 hours, the variance depending upon the dose given.


most of us have likely taken caffeine, so when he made that bold statement i griningly asked him if he was stating that the initial effects were placebo. he stuck to his statement so i told him i would find out if there was any truth to it in a few days.

thanks T-Nation.

thanks Cy.


Not to mention a whole lot of "supplement manufacturers" who have hung their collective hats on caffeine being a key ingredient in "fat burning."