Too much caffeine: signs you are overdoing it

How much is considered safe

For healthy adults, the US agency FDA cites 400 milligrams of caffeine per day as an amount that is generally not associated with dangerous effects. The European authority EFSA reaches a similar value and adds that single doses of up to 200 mg are not a concern in adults. For pregnant women, EFSA considers up to 200 mg a day safe.

These numbers are general references. Some people are much more sensitive, and anyone with a heart condition, anxiety, reflux or who takes certain medications should talk to a doctor.

Source: FDA, how much caffeine is too much and EFSA, caffeine.

Where your day's caffeine comes from

The amount varies a lot with preparation and brand, so it is worth checking the label when there is one. As a rough order of magnitude, a cup of filtered coffee usually has more caffeine than a can of cola, and energy drinks can have as much as a coffee, or more, per can. Black tea and yerba mate count too, as do chocolate and some headache medications.

The common mistake is to count only coffees and forget the rest. Add everything up for a day or two to get a real idea.

Signs you have gone too far

• Racing or pounding heart.
• Shaky hands, agitation or nervousness.
• Trouble falling asleep even when tired.
• Headache, nausea or stomach discomfort.
• Needing to urinate more often.

If these signs show up on the days with more coffee, the link is likely.

How to cut back without suffering

Quitting all at once can cause headache and tiredness for a few days. Cutting back gradually works better: drop one dose a week, swap the afternoon coffee for decaf or herbal tea, and avoid caffeine in the six hours before bed.

Sleep usually improves along with it. See nighttime habits for sleeping better and why you wake up at night.

The numbers that serve as a reference

The FDA, the US food agency, cites 400 mg of caffeine per day as an amount generally not associated with negative effects in healthy adults, equivalent to about four to five cups of filtered coffee.

The opinion of EFSA, the European authority, reaches similar values: up to 400 mg over the day and up to 200 mg at once for healthy adults, with a tighter recommendation, up to 200 mg a day, for pregnant and breastfeeding women.

Source: FDA, how much caffeine is too much.

Source: EFSA, Scientific Opinion on the safety of caffeine, EFSA Journal, 2015.

Why the 4 p.m. coffee hurts your sleep

Caffeine has a long half-life: much of what you drink is still in your body hours later. That is why a mid-afternoon dose can still be acting at bedtime, even in people who say they feel no effect.

This is also the reason for the cycle many people live: sleep badly, wake up tired, raise the caffeine dose, sleep even worse. To test whether it is your case, cut back gradually and watch your sleep for two weeks, instead of quitting at once, which usually brings headache and irritability.

When to seek help

Strong palpitations, chest pain, shortness of breath or fainting call for immediate care. Energy drinks mixed with alcohol or very high intake in a short time also deserve attention. If you cannot cut back, or feel you need caffeine to function every day, you can talk to a doctor.