How much caffeine a day is too much?

Concerns & risks

You drink caffeine from several sources and want to know if you're overdoing it.

Causes & evidence

The FDA says that for healthy adults, 400 milligrams of caffeine a day, roughly four or five cups of coffee, is an amount not generally associated with dangerous, negative effects. People differ in how sensitive they are to caffeine and how quickly they break it down. The FDA notes that consuming too much can cause insomnia, jitters, anxiety, a fast heart rate, upset stomach, nausea, headache and a feeling of unhappiness. Caffeine content varies widely between drinks, and energy drinks and some supplements can contain a lot. Pregnant people, those who are breastfeeding, people with certain conditions and those on some medications should ask a health care provider about limits.

Caffeine affects people differently, and some medications interact with it. Powdered and highly concentrated caffeine products can be dangerous because small measuring errors can give large doses.

Counting 'cups' instead of milligrams hides how much an energy drink or large coffee adds.

What to do

1. Read labels for caffeine content on energy drinks and supplements.
2. Add up your daily total in milligrams.
3. Move your last caffeinated drink earlier in the day.
4. Cut back gradually to avoid withdrawal headaches.
5. Talk with a provider if symptoms such as a fast heartbeat continue.

Common mistakes:

• Ignoring energy drinks and pre-workout powders
• Assuming all coffees are the same size and strength
• Quitting abruptly

ReportSpeedMan tip: Swapping one drink a day for a decaf or half-caf version is an easy way to cut back without feeling it.

What I would actually do

I'd tally a typical day in milligrams, then move my last caffeine to early afternoon before cutting the amount.

The trade-off people miss: 400 mg is a general reference for healthy adults, not a target. If your sleep suffers at much less, your personal limit is lower.

How to know it worked

Your daily total is under your limit and you sleep better.

Quick FAQ

Is decaf caffeine-free?
It has a small amount.

Does caffeine dehydrate me?
Moderate amounts from drinks still count toward fluids.

How long does caffeine last?
Effects can last several hours.

Wrap-up: Use 400 mg as the reference, count all your sources and adjust if sleep or jitters tell you it's too much.

Wiki: Sleep Basics and Insomnia and Common Cold vs. Flu.

How much caffeine a day is too much: official pages behind this answer

• FDA: Spilling the beans: how much caffeine is too much?
• MedlinePlus: Caffeine