The U.S. Food and Drug Administration (FDA) cites 400 milligrams (mg) of caffeine a day—about two to three 12-fluid-ounce cups of coffee—as an amount not generally associated with negative effects for most adults. It is not an intake target, a diagnosis, or a universal cutoff. Sensitivity, medications, certain health conditions, pregnancy, and the rate at which a person eliminates caffeine can all change what is appropriate. FDA caffeine guidance
Count caffeine from every source
Coffee is only one source. The FDA notes that caffeine may also be found in tea, chocolate, soft drinks, energy drinks, bars, ice cream, chewing gum, dietary supplements, and some over-the-counter medicines. Caffeine amounts and container sizes vary, and restaurants are not required to disclose caffeine content. Check a packaged product’s label when it provides a milligram amount; for an unlabeled restaurant drink or packaged product, ask the retailer or manufacturer rather than assuming that one serving matches another. FDA caffeine guidance
A practical starting point is to total the milligrams shown on labels across the day. Treat estimates for brewed coffee and café drinks as estimates, not fixed values. The FDA’s examples show that even products within the same broad category can vary substantially. FDA caffeine guidance
Pregnancy guidance uses more than one threshold
The 400 mg figure should not be carried over to pregnancy. The American College of Obstetricians and Gynecologists (ACOG) states that caffeine intake below 200 mg per day does not appear to be a major contributing factor in miscarriage or preterm birth. Its guidance also says that the relationship with growth restriction remains undetermined and that no final conclusion can be made about high intake and miscarriage. ACOG guidance
The World Health Organization (WHO) uses a different formulation: it recommends that pregnant people with high daily intake, defined as more than 300 mg per day, lower their intake to reduce the risk of pregnancy loss and low-birth-weight neonates. WHO recommendation These are not identical statements or interchangeable personal limits. Anyone pregnant, trying to become pregnant, or breastfeeding should discuss caffeine use with their obstetric clinician; the FDA similarly advises consulting a health care provider in these circumstances. FDA caffeine guidance
Children and teens
For young people, the guidance is more cautious and is not captured by the adult 400 mg figure. The U.S. Dietary Guidelines, as summarized by the FDA, say that caffeinated drinks should be avoided for children younger than 2. The FDA also says medical experts advise against energy drinks for children and teens, and it directs families to discuss a child’s or teen’s caffeine consumption with a health professional. FDA caffeine guidance
Health Canada publishes a separate, precautionary recommended maximum daily intake of 2.5 mg per kilogram of body weight for children and adolescents through age 18. It says this approach reflects limited data for children and insufficient data for adolescents, and notes that some older, heavier adolescents may be able to consume caffeine similarly to healthy adults. Health Canada guidance This is agency-specific guidance, not a reason to apply an adult benchmark to every young person.
Consider sleep in relation to bedtime
There is no evidence-based universal clock time at which everyone should stop caffeine. Dose and the time before a person’s usual bedtime matter. In a randomized home-based study, a 400 mg dose taken at bedtime, three hours before bedtime, or six hours before bedtime significantly disrupted objective sleep compared with placebo. The study supports being cautious with substantial caffeine close to bedtime; it does not establish a one-size-fits-all afternoon cutoff or predict every person’s response. Journal of Clinical Sleep Medicine study
Signs that intake may be too high
The FDA lists increased heart rate, heart palpitations, high blood pressure, insomnia or sleep disruption, anxiety, jitters, upset stomach, nausea, and headache among possible effects of too much caffeine. These symptoms can have causes other than caffeine, so they are a reason to discuss caffeine use and other concerns with a health care professional rather than self-diagnose. FDA caffeine guidance
Some situations require urgent help. Seek emergency care or contact local emergency services or a poison center for chest pain, a severe or irregular heartbeat, seizures, or suspected overdose—especially after a pure or highly concentrated caffeine product. The FDA says that rapidly consuming around 1,200 mg of caffeine can produce toxic effects such as seizures and warns that pure or highly concentrated products can have serious health consequences. FDA caffeine guidance
A measured way to use the guidance
Use 400 mg as qualified population guidance for most adults, not as a goal. Add up caffeine from all sources, rely on product labels where available, and account for how caffeine relates to sleep. If you have a medical condition, take medicines, are pregnant or breastfeeding, or have recurring symptoms after caffeine, bring the product labels or estimated amounts to a clinician or pharmacist. If you choose to reduce regular caffeine intake, the FDA advises doing so gradually because withdrawal is not considered dangerous but can be unpleasant. FDA caffeine guidance