Caffeine Absorption


How Quickly Does Caffeine Enter The Bloodstream?

Those that are regular consumers of coffee or energy drinks have figured out that it takes about 15-20 minutes before the effects of caffeine are realized.

Energy shots can be a tad quicker since there is less liquid to drink and food items such as caffeinated gum or chews can be even quicker since some of the caffeine is absorbed through the lining of the mouth.

However, feeling alert doesn’t really tell us how long it takes for all of the caffeine to be fully absorbed into the bloodstream. This is a bit more complicated.

Luckily, there have been a few scientific studies that have measured how fast caffeine via different mediums is completely absorbed by the bloodstream.

Caffeine Absorption Rates

Caffeine MediumAmountBioavailabilityBlood Saturation
Caffeine Capsules¹200mg90%84-120 minutes
Caffeine Gum¹200mg77%44-80 minutes
Coffee²200mg99%42-39 minutes
Energy Drink²200mg99%42-39 minutes

Looking at the above data, we can glean some interesting information. 

  1. Liquid is the overall best caffeine delivery method with the most caffeine being absorbed in the least amount of time to fully saturate blood plasma.
  2. The effects of caffeine gum are quicker, but less caffeine is absorbed overall. An advertised 100mg caffeine piece of gum would really only deliver 77mg of caffeine.
  3. Caffeine capsules and tablets take the longest to fully saturate the blood since they have to dissolve in the stomach first.

We couldn’t locate any data on caffeine candies such as LiveWire Chews or Jelly Belly Extreme Sports Beans, but since these items are completely dissolved by the saliva and swallowed, they would most likely have similar results as the liquid caffeine delivery agents.

As for caffeinated gum, our guess would be that caffeine gum has less bioavailability because some of the caffeine gets trapped in the gum material, which is not fully consumed.

Is Caffeine on an Empty Stomach Best?

Many people report that drinking caffeine on an empty stomach provides faster absorption than drinking caffeine with food or after eating.

There was some research³ into this notion and it found that the rate of stomach emptying did speed up or slow down blood saturation rates. People with full stomachs, especially those given a high fiber (hard to digest) meal had slower caffeine absorption rates.

Some people report consuming caffeine on an empty stomach causes indigestion.

Different Times Call For Different Caffeine

Caffeine absorption isn’t as straight forward as people might think since there are several variables that influence how quickly it saturates the bloodstream. While there are many ways to consume caffeine, the best way may depend on the situation a people find themselves in.

If a person needs to feel the effects of caffeine quicker, gum or candy would be in order. But, if a person wants to get the most bang for their buck, then caffeine in liquid form will deliver the exact dose they had hoped for.

This article only covers caffeine absorption, so If you also want to learn about caffeine metabolism look here and see this article for information about the half life of caffeine. 

2. Caffeine for the Sustainment of Mental Task Performance: Formulations for Military Operations ( 2001 )

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  • Badger

    Wat About Caffeine disapation? How long does it take for caffiene to disapate from your body to determine exactly how long you have to ingest the caffiene to DIE. or the limit of time so you can slow down so u dont die. On average the human body can filter out 3oz of alcohol an hour. so wats caffiene?

  • wardy

    hey i luv tht

  • Drop

    Just to let you know…….the LD50 for Caffeine is 10,000mg/KG, i dont think a line or 2 of caffeine is going to kill you.
    As for “Don’t try this at home, it’s dangerous and you might die.”

    Yeah i suppose you would if you crushed up around, oh, say…….100 No-Doze and snorted them all!! In One GO.

  • Evil Monkey

    No, the LD_50 for caffeine is about 150mg/kg. That equates to about 10 grams for the average person, via oral administration.

    A line probably won’t kill you, but remember, this is just for death by caffeine. If you have heart problems, blood pressure problems, mental problems, or something else, you might die a lot sooner.

  • I think you mean “Absorption” which is a little funny because it invokes the b->p rule…

  • johnny-john-j-joe

    I’m so there.

  • caffeinated lady

    I really don’t see how crushing a caffeine pill and eating half could kill you. I do this every day and have for years! I buy the 200 mg pills because they are cheaper than 100 mg ones. I split them in half always. Then I eat half, letting it disolve before swallowing because I have trouble swallowing pills. It works fine for me in place of coffee two or three times a day!

  • devv

    so..this is kinda bull on the 150mg killing you

    see…i’m 18
    since i’ve been about 15 i’ve gone through a 12 pack of mt dew a day…not to mention a capachino every morning…

    if caffeine in that amount were deadly….i wouldn’t be here

    i would say u are more likely to choke on the damn thing then u are to overdose

  • bob

    i went to a site that sold caffeine. they warned against more than a gram at a time. it is possible to get caffeine poisoning tho

  • facforrester

    i’ve taken JET ALERTS for 5-6 years,i crushed one,took half of it . i never really noticed much diference,but i also take 130 mgs methadone daily too.

  • Nev

    To devv:

    Mountain dew has 55mg/12oz of liquid. An espresso has anywhere from 100-200mg per shot.

    Total you are talking about 660mg for the 12-pack, and (assuming a single-shot espresso) and additional 200mg. Thats a total of 860mg (or 0.86g) of caffeine over probably 12 hours or more. LD50 of caffeine is 10g INSTANTANEOUS ABSORPTION (Meaning taken all at once). You aren’t taking anywhere near that amount and definitely not at once.

  • Nev

    To facforrester:

    You are probably immune to the effects of it. Try to discontinue for a month (or at least a few weeks) then do the same thing. You’ll notice a difference.

  • stuck

    i am trying to do my crswk on the effect of caffeine on the nervous system, none of you have helped me!

  • kurtk

    Having suffered from sleep problems for a while now, I’ve been experimenting a little with different caffeine administration routes, and the best by far is sublingualy.

    Just break off 50mgs of a caffeine tablet and chew it up with a piece of gum or two. It diffuses through the mucous membranes in your cheeks and under your tongue, and hits your bloodstream almost instantly. Lasts for about an hour.

    Also, something I read in National Geographic that you caffeine freaks might want to make note of… nicotine doubles the rate that caffeine is metabolized into the body. A small downside to this, I guess, is that a person on caffeine only absorbs half the nicotine he would under normal circumstances.

    Just some food for thought. Wonder if the gum route works for ambien? 🙂

  • porknbeans

    @caffeinated lady:Do you dissolve the pill in liquid or just in your mouth?

    One thing about the guy’s post was, “The problem is that while I was reaching for the water, it crumbled to dust in my mouth.I swallowed it anyway, and realized my mistake in seconds.”

    So he actually had just the powder in his mouth and swallowed it without water, as he was reaching for it. If he had mixed it in the water I wonder if it would’ve been different.

  • Felix the Cat

    The best way I’ve found to administer caffeine is by sucking on the beans. You can hold hem in your cheeks.

  • Tommy

    Yeah kids, better get some high quality coke

  • Appledystopia

    I agree with the caffeine and gum suggestion that kurtk suggests. I did it once, and it worked wonders, and I Googled it to see if anyone else does it. If you do it, you want to use NoDoz or something that doesn’t taste too bad. Vivarin tastes awful.

    I agree 100%. It hits you fast, as it is absorbed sublingually. I did this at a concert, and it hit me fast, just as I was starting to lose energy. I didn’t have a drink with me to swallow a pill. Necessity is the mother of invention…

    By the way, it did make the gum break down and turn into sludge after a while. I was chewing Eclipse. I think maybe the starch in the pill does that. But this was after chewing it for 30 minutes. The caffeine will probably absorb in less then 10. Get rid of the gum before it turns into sludge…

    I am a programmer too, but I don’t do oodles of caffeine. I actually quit drinking coffee regularly about 10 years ago. I do green tea now. It has a small amount of caffeine, but the stimulant effect comes from theanine. I did this after discovering Dr. Nicolas Perricone on PBS. He strongly recommends not drinking coffee. After 10 years, I still get carded for beer, and I am much older than 21. Almost twice that…

    I found that I would stress out too much with caffeine, which isn’t good in the pressure cooker of the Silicon Valley. Coffee releases the stress hormone cortisol. Even one cup will release cortisol and keep the levels elevated all day. It makes you feel stressed out, stores belly fat, causes skin to thin and wrinkle (as well as increasing stretch marks) and even causes brain cells to die. In other words, it makes you age rapidly. Cortisol is the “fight or flight” hormone. It is meant to be released in emergencies, not every day. Also, it causes adrenal depletion. That’s why you feel so great after that one cup in the morning (and you will get so much done!) and then you fade out… There is only so much adrenalin that will be produced and released.

    I still do take the occasional caffeine pill, but I break a 200mg in half. I will take caffeine before hitting the gym. The increase in testosterone offsets the effects of cortisol. I also take it in emergencies or if I am out at a party or drinking. While I don’t drive drunk, I find that driving home late at night after a couple drinks were consumed earlier makes me feel tired.

  • Laura

    Why does a 12 oz. red bull give me less of a kick than one level teaspoon of instant coffee prepared in 6-8 ounces of liquid?

  • Layster

    This is really helpfull. But I have no idea why no one has made an energy drink family tree i would really like to know the relationships between companies

Last Modified: September 11, 2014