How to get caffeine out of your system
You cannot flush caffeine out of your system. Nothing you drink, eat or do changes the speed much. The liver breaks caffeine down at its own pace, and for a healthy adult about half of it is gone every 5 to 6 hours.
What you can do is stop adding to it, take the edge off the symptoms, and know how long the wait will be.
Try it with your drink
Half-life 5.7 h · peak at 45 min · sleep threshold 40 mg
How long until the caffeine wears off?
It depends on how much you had. The worst of it passes first: caffeine peaks about 45 minutes after a drink, and the shaky, wired feeling eases as the level starts to fall.
| Dose | At the peak | After 6 hours | Below 40 mg after |
|---|---|---|---|
| 100 mg | 91 mg | 49 mg | 7 and a half hours |
| 200 mg | 183 mg | 99 mg | 13 and a half hours |
| 300 mg | 274 mg | 148 mg | 17 hours |
| 400 mg | 365 mg | 198 mg | 19 hours |
| 600 mg | 548 mg | 296 mg | 22 and a half hours |
The last column is the point where this site treats the dose as low enough to sleep on. If you cleared caffeine slowly, from pregnancy, the contraceptive pill or some medicines, add a third or more. Every figure is worked out the same way, and the method is on its own page.
What helps while you wait
- Stop taking more. Check for caffeine you did not count: cola, tea, chocolate, pre-workout, and some headache tablets.
- Drink water. It does not flush caffeine out. It helps because being dehydrated makes a pounding heart and a headache feel worse.
- Eat something. If the drink was recent, food in the stomach slows absorption and blunts the peak. Plain food with some fat and protein is easier on a jumpy stomach than sugar.
- Walk. Ten or twenty minutes of easy movement gives the restlessness somewhere to go. Keep it gentle. A hard workout pushes an already fast heart rate higher.
- Slow your breathing. Breathe in for four counts and out for six, for a few minutes. It will not lower the caffeine, but it does calm the body's alarm response, and that is most of what you are feeling.
- Skip other stimulants. Nicotine and decongestants stack on top of caffeine.
Most of what feels like too much caffeine is the peak. It passes in an hour or two, long before the caffeine itself is gone.
What does not work
Drinking a lot of water. Caffeine is removed by liver enzymes, not rinsed out by the kidneys. Extra water sends you to the toilet more and changes nothing else.
Sweating it out. A sauna or a hard run does not clear caffeine faster in any way that matters, and both raise the heart rate you are trying to bring down.
Supplements. L-theanine, vitamin C and activated charcoal are all suggested online. There is no good evidence that any of them shortens the time caffeine stays in an adult who drank too much coffee.
Sleeping it off early. You can lie down, but caffeine that is still high will keep you in light sleep. Rest anyway, in a dim room. It is still better than another hour of scrolling.
When too much caffeine is an emergency
Too much coffee is unpleasant. It is rarely dangerous. The risk is with concentrated caffeine: powders, tablets and some pre-workout products, where a spoon can hold more than a dozen cups.
The US Food and Drug Administration estimates that toxic effects, such as seizures, can appear with around 1,200 mg taken quickly.
Get emergency help if you have:
- chest pain or an irregular, pounding heartbeat that does not settle
- vomiting that will not stop
- confusion, or great difficulty staying calm
- a seizure, or fainting
If someone has swallowed caffeine powder or a handful of tablets, call your local poison centre or emergency number. Do not wait for symptoms.
If it is already bedtime
You will probably sleep badly tonight, and the useful part is tomorrow. Do not lie in bed fighting it. Keep the lights low, stay off bright screens, and get up at your usual time even after a short night. Sleeping in moves the problem to the next evening.
Then move the last cup earlier. For an 11 pm bedtime a regular coffee should be finished by mid-afternoon, and a 200 mg energy drink before ten in the morning. The cutoff for your own bedtime is worked out drink by drink.
How to stop it happening again
Count the whole day. Most people who feel overcaffeinated did not have one huge drink. They had four ordinary ones. The daily limit for a healthy adult is 400 mg, and the full list of drinks shows how fast that adds up.
Watch the single dose. The European Food Safety Authority considers up to 200 mg at once safe for a healthy adult. A large cold brew or a can of Celsius is already there.
Do not drink it on an empty stomach if you are prone to jitters. The same dose peaks higher and faster.
Sources
- US Food and Drug Administration. Spilling the Beans: How Much Caffeine Is Too Much?
- EFSA Panel on Dietetic Products, Nutrition and Allergies. Scientific Opinion on the safety of caffeine. EFSA Journal, 2015.
- Institute of Medicine. Caffeine for the Sustainment of Mental Task Performance, chapter 2. National Academies Press, 2001.
Common questions
How do you get caffeine out of your system fast?
You cannot speed it up in any meaningful way. The liver removes about half of the caffeine every 5 to 6 hours. Stop taking more, drink water, eat something, walk, and wait. The jitters usually ease within a few hours as the peak passes.
Does drinking water flush out caffeine?
No. Water does not change how fast the liver breaks caffeine down. It helps if you are dehydrated, which makes a racing heart and a headache feel worse.
How long does it take for caffeine to leave your system?
A 100 mg coffee falls under 40 mg, the line Cira uses as low enough to sleep on, in about seven and a half hours. 200 mg takes about thirteen and a half. Traces remain for a day or more.
When is too much caffeine an emergency?
Chest pain, an irregular heartbeat, repeated vomiting, confusion or a seizure need emergency care. The US FDA puts toxic effects at around 1,200 mg taken quickly, an amount that usually comes from powders or tablets.