This is not medical advice. If you believe you are at risk, please seek immediate medical attention.
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Is there a way to reduce the quantity of caffeine on your body, like a caffeine antidote?
For example, if you take an espresso or a certain amount of coffee to keep you awake (for finish a work or study), but then you realize that you don't need to be awake all night, is there something that counteracts caffeine's effects (food or drink for example) on your body?
I've searched in your FAQ, but didn't find anything.
Thanks in advance,
How to get caffeine out of your system
The best answer is: time and planning.
Setting a time limit on caffeine consumption (such as last drink by 4 PM) can help to ensure you're mostly free of caffeine's effects by bed time. You should also plan you
A healthy adult's half life for caffeine is approximately 5.7 hours (see: NIH).
If you take an average 1.5 oz espresso made from 7 g of espresso beans that contains 77 mg of caffeine at 8 PM, you would still have almost 40 mg in your body by 2 AM!
Studies on rats suggest that a chemical known as Rutaecarpine may increase the rate at which caffeine is metabolized, in rats. While this is yet to be studied in humans, herbal supplements have popped up on the market containing Rutaecarpine that people can take at their own risk.
Anything you're consuming is going to take time to counteract the effect of caffeine however, and will not provide immediate relief. While there have been very few cases of caffeine causing death (most are related to alcohol, or caffeine exasperating other conditions), you should go to the emergency room if you feel you may be in serious danger.
Regular overdoing it with your caffeine consumption can lead to nasty withdrawal symptoms - this can be avoided by avoiding regular high doses of caffeine in the first place.
Nicotine as a remedy
Smoking (nicotine) has been shown to increase the metabolism of caffeine (source) from about 6 hours down to 3.5 hours, clearing it out of your system faster. It makes it an "antidote" in a very loose way.
This however, introduces nicotine into your body, which is another stimulant, and is just terribly unhealthy.
Garlic as a remedy
There are no known methods by which garlic can help counteract having too much caffeine. This is an old wive's tale.
Bananas as a remedy
Similar to Garlic, there is nothing in Bananas that is known to counteract caffeine. Bananas are known to be a good source of potassium, so if you're experiencing cramps due to dehydration from caffeine's diuretic effects, they may help alleviate cramping symptoms.
Being dehydrated can increase the negative effects of caffeine - jitters, headache, increased heart rate. These are all signs your body is in distress and can work to multiply the bad reaction.
It's important not to overdo it though, over-hydration can lead to increase blood pressure (among other problems), which can just compound the effect of a raised blood pressure from caffeine.
A little planning
Ultimately, you're best off planning your hard work earlier in the day rather than relying on caffeine to keep you up. If you absolutely need to have something done for the next day, it's better to sleep now and wake up early, have that loving cup of coffee to get you alert, and get the work done early in the morning.
See other tips on how to cut your caffeine intake.
Additional reading: https://www.ncbi.nlm.nih.gov/books/NBK223808/