Most bad caffeine days are not overdoses, they are overshoots. But there is a real line, and it is worth knowing which side of it you are on.
Where the numbers sit
- Up to 400 mg a day is considered fine for healthy adults by both the FDA and EFSA.
- 200 mg in one sitting is the single-dose figure EFSA treats as safe.
- Above roughly 600 mg most people get clearly unpleasant symptoms.
- Serious toxicity generally needs far more, in the range of 1,200 mg taken quickly, which is hard to reach with drinks and easy to reach with powders or pills.
Ordinary too much
Shaky hands, a racing heart, nausea, a headache, trouble sleeping, irritability, needing the bathroom constantly. Unpleasant, not dangerous, and it passes as the caffeine clears.
Signs that need medical help
- Chest pain, or a heartbeat that is fast and irregular
- Vomiting that will not stop
- Confusion, hallucinations or disorientation
- Convulsions or fainting
Any of those, especially after pills, powder or several energy drinks, is a call to emergency services rather than a wait-and-see. Risk is higher for children, teenagers, people with heart conditions and anyone on medication that slows caffeine clearance.
The everyday version of this problem is losing count. Caffy keeps the running total so 400 mg stays a number you can see rather than one you guess at.