How Much Caffeine Is Too Much?

For most healthy adults, up to 400 milligrams (mg) of caffeine a day is an amount the FDA says is not generally linked to negative effects. That’s roughly two to three 12-ounce cups of coffee (FDA). The European Food Safety Authority (EFSA) arrived at the same 400 mg daily figure, and it adds that a single dose of up to 200 mg is not a safety concern for healthy adults (EFSA). Lower limits apply during pregnancy and for children, and the right amount can be lower for anyone who is sensitive to caffeine or takes certain medications.

Daily limits at a glance

Who	Upper limit	Source
Healthy adults	400 mg a day	FDA, EFSA
Healthy adults, single dose	200 mg at a time	EFSA
Pregnant	Less than 200 mg a day	ACOG, EFSA
Breastfeeding	200 mg a day in Europe; 300 to 500 mg might be safe for most mothers, per NIH	LactMed
Children and teens	3 mg per kilogram of body weight a day in Europe; no FDA number	EFSA, FDA
Under age 2	Avoid caffeinated drinks	FDA

Healthy adults

The 400 mg figure is a ceiling, and some people have trouble well below it. The FDA says people vary widely in how sensitive they are to caffeine and in how quickly their bodies clear it. Some health conditions make people more sensitive, and so do some medications (FDA).

MedlinePlus suggests checking with your health care provider about limiting or avoiding caffeine if you have a sleep disorder, migraines, anxiety, GERD or ulcers, an abnormal heart rhythm, or high blood pressure (MedlinePlus). If you take prescription medicines, ask your doctor or pharmacist about caffeine. Some drugs slow how fast your body breaks it down, which our guide on how long caffeine lasts covers.

How you spread it out counts as well. EFSA’s safety finding for single doses stops at 200 mg for healthy adults (EFSA), so a large coffee and an energy drink back to back can go past that in one sitting even when your daily total stays under 400 mg.

Pregnancy and breastfeeding

The American College of Obstetricians and Gynecologists (ACOG) says moderate caffeine intake, less than 200 mg a day, does not appear to be a major factor in miscarriage or preterm birth. It also says the link between caffeine and restricted fetal growth hasn’t been settled. ACOG first issued this opinion in 2010 and reaffirmed it in 2026 (ACOG). EFSA uses the same 200 mg a day for caffeine from all sources (EFSA). The FDA doesn’t give a pregnancy number. It recommends talking to your health care provider about limiting caffeine if you’re pregnant, trying to become pregnant or breastfeeding (FDA). Caffeine passes through the placenta to the baby (MedlinePlus).

The numbers for breastfeeding vary more. The NIH’s LactMed database (last revised April 15, 2026) says there isn’t enough high-quality data for firm evidence-based advice. It suggests 300 to 500 mg a day might be safe for most mothers, while noting that European authorities set a likely safe level of 200 mg. It advises lower intake for mothers of premature and very young babies, who clear caffeine very slowly (LactMed). LactMed’s revision is more recent than the FDA page (updated August 2024), which gives no number. Your own provider is the best person to help you choose a number.

Children and teens

US guidance doesn’t give a milligram limit for kids. The FDA points to the Dietary Guidelines for Americans, which say children under 2 shouldn’t have caffeinated drinks, and it asks parents to talk with a health care professional about how much caffeine an older child or teen has (FDA). The American Academy of Pediatrics concluded in a 2011 clinical report that the caffeine and other stimulants in energy drinks have no place in the diets of children and adolescents (AAP, Pediatrics).

EFSA proposes a safety level of 3 mg per kilogram of body weight a day for children and adolescents who have caffeine regularly (EFSA). For a teen who weighs 50 kg (about 110 pounds), that comes to 150 mg a day. Children can be especially sensitive to caffeine’s effects (MedlinePlus).

Signs you’ve had too much

The FDA lists these symptoms of too much caffeine (FDA):

• Faster heart rate or heart palpitations
• High blood pressure
• Insomnia or disrupted sleep
• Anxiety or jitters
• Upset stomach or nausea
• Headache

If you get any of these, the FDA suggests talking with your health care professional about your caffeine intake (same source).

Large amounts taken quickly are dangerous. The FDA estimates that toxic effects such as seizures can occur after rapidly consuming around 1,200 mg of caffeine (FDA). A StatPearls review lists a fast or irregular heartbeat, changes in mental state and seizures among the effects at that dose (StatPearls). Overdose symptoms can include trouble breathing, confusion or hallucinations, seizures, an irregular or rapid heartbeat, fever, and vomiting. If someone may have overdosed, call 911 or your local emergency number. For advice, call the Poison Help line at 1-800-222-1222 (MedlinePlus).

How much caffeine is in common drinks

The FDA gives these typical ranges for 12 fluid ounces of each drink (FDA):

Drink (12 fl oz)	Typical caffeine
Caffeinated soft drink	23 to 83 mg
Green tea	37 mg
Black tea	71 mg
Brewed coffee	113 to 247 mg
Energy drink	41 to 246 mg

Serving size changes the math. The FDA says energy drinks generally contain 54 to 328 mg per 16 fluid ounces (same source). Using the top of the brewed coffee range, two 12-ounce cups come to nearly 500 mg.

Caffeine around workouts

Caffeine can help performance. A 2021 position stand from the International Society of Sports Nutrition found that it consistently improves exercise performance at 3 to 6 mg per kilogram of body weight. It notes the smallest effective dose may be as low as 2 mg/kg, and that very high doses (such as 9 mg/kg) bring a high rate of side effects without adding benefit. The most common timing is 60 minutes before exercise (Guest et al., 2021).

The safety research points in a more cautious direction. EFSA found that a single dose of up to 200 mg is not a safety concern for healthy adults when taken less than two hours before intense exercise. It notes there are no studies in pregnant women or in middle-aged and older adults doing intense exercise (EFSA). At 3 to 6 mg/kg, a 70 kg (154-pound) adult would take 210 to 420 mg at once, which is more than the single dose EFSA judged safe. The sports society was asking what improves performance and EFSA was asking what is safe, so if you’re using caffeine before a hard session like HIIT, EFSA’s 200 mg is the more conservative ceiling. Count that dose toward your daily total too.

If you train in the evening, think about your sleep as well. A 2023 meta-analysis of 24 studies estimated that a standard pre-workout serving of 217.5 mg should be taken at least 13.2 hours before bedtime to avoid losing sleep (Gardiner et al., 2023). The how long caffeine lasts guide covers caffeine’s half-life and sleep timing in more detail.