How Much Caffeine Is Safe in a Day?

For most healthy adults, up to 400 mg of caffeine a day isn’t associated with harmful effects, according to both the US Food and Drug Administration (FDA) and the European Food Safety Authority (EFSA). The FDA puts that at about two to three 12 fl oz (355 mL) cups of coffee. Lower limits apply in pregnancy, to a single dose, and to people who are sensitive to it.

This article is general information, not medical advice. Ask your doctor if you’re pregnant, have a heart rhythm condition, anxiety, or high blood pressure, or take medicines that interact with caffeine.

The Limits

EFSA’s 2015 scientific opinion on the safety of caffeine concluded, for healthy adults:

• Up to 400 mg a day from all sources doesn’t raise safety concerns.
• Single doses of up to 200 mg, about 3 mg per kilogram of body weight, don’t raise safety concerns, including shortly before intense exercise.
• In pregnancy and while breastfeeding, up to 200 mg a day doesn’t raise concerns for the fetus or infant.

The FDA cites 400 mg a day as an amount not generally associated with negative effects for most adults, and notes wide variation in how sensitive people are and how fast they clear it.

How Much Is in Your Drinks

Caffeine content varies a lot by drink, brew, and brand, so labels and your own logging are the best guide. As examples, a 2023 meta-analysis of caffeine and sleep by Gardiner and colleagues used 107 mg for a 250 mL cup of coffee and 217.5 mg for a standard serving of pre-workout supplement. Energy drinks and supplements can contain 200 mg or more in one serving.

Signs of Too Much

The FDA lists signs such as a fast heart rate, palpitations, high blood pressure, disturbed sleep, anxiety, jitters, an upset stomach, nausea, and headache, and urges caution with concentrated caffeine products. Caffeine late in the day can disturb sleep even when you don’t feel it; see How Late Can You Have Caffeine Without Hurting Your Sleep?

Following It in Kaizora

Dietary Caffeine comes from the foods and drinks you log on Food Log, and from Cronometer’s import and Apple Health’s export, counted at the time you had it. A habit such as “at most 400 mg of caffeine a day” checks your total each day and notifies you on the day it first goes over; see Habits.

The Short Version

• Up to 400 mg a day is safe for most healthy adults, by the FDA and EFSA.
• Keep single doses to about 200 mg, and to 200 mg a day in pregnancy.
• A cup of coffee often holds around 100 mg; energy drinks and supplements can hold much more.

Sources

• European Food Safety Authority Panel on Dietetic Products, Nutrition and Allergies, “Scientific opinion on the safety of caffeine,” EFSA Journal 13, no. 5 (2015): 4102. doi:10.2903/j.efsa.2015.4102
• Gardiner C et al., “The effect of caffeine on subsequent sleep: a systematic review and meta-analysis,” Sleep Medicine Reviews 69 (2023): 101764. doi:10.1016/j.smrv.2023.101764
• US Food and Drug Administration, Spilling the Beans: How Much Caffeine Is Too Much?