Caffeine: How Much Is Too Much?
FDA cites 400 mg of caffeine a day as an amount not generally associated with negative effects for most adults. See what that means in cups, who needs less and the signs of too much.
Key takeaways
- For most adults, FDA has cited 400 milligrams a day, about two to three 12-fluid-ounce cups of coffee, as an amount not generally associated with negative effects.
- CDC puts the same 400 mg as about 2 to 3 cups of plain coffee. Count every source, because caffeine also turns up in tea, soda, energy drinks, chocolate and some medicines.
- Caffeine varies a lot by drink: FDA lists 113 to 247 milligrams for a 12-fluid-ounce regular brewed coffee and 41 to 246 milligrams for a 12-fluid-ounce energy drink.
- If you're pregnant, the NHS says do not have more than 200mg of caffeine a day. FDA says to talk to your health care provider if you're pregnant, trying to become pregnant or breastfeeding.
Most adults can fit a few cups of coffee into a day without trouble, but the limit depends on your cup size, your other drinks and your health. Start by adding up every source of caffeine you have in a typical day, then compare it with the numbers below.
The 400 mg figure and what it means in cups
For most adults, FDA has cited 400 milligrams a day, about two to three 12-fluid-ounce cups of coffee, as an amount not generally associated with negative effects. CDC uses the same number, saying moderate caffeine consumption (up to 400 mg per day) can be a part of a healthy diet for most adults, which is about 2 to 3 cups of plain coffee.
The cup size is the detail people miss. FDA spells out 12-fluid-ounce cups, while CDC just says cups, so measure your usual mug or check the size printed on a takeout cup before you count. “Three cups” can mean very different amounts of caffeine depending on what you pour into.
FDA also makes clear that the 400 milligram figure won’t fit everyone. There is wide variation in both how sensitive people are to the effects of caffeine and how fast they eliminate it from the body, and body weight, medicines, certain medical conditions and individual sensitivity all change what “too much” means for you.
How much caffeine is in common drinks
Caffeine content swings widely, even within one kind of drink. The table uses the typical amounts FDA lists on its caffeine consumer page, all for 12-fluid-ounce drinks unless noted:
| Drink | Typical caffeine (FDA) |
|---|---|
| Caffeinated soft drink, 12 fl oz | 23 to 83 milligrams |
| Green tea, 12 fl oz | 37 milligrams |
| Black tea, 12 fl oz | 71 milligrams |
| Coffee, regular brewed non-specialty, 12 fl oz | 113 to 247 milligrams |
| Energy drink, 12 fl oz | 41 to 246 milligrams |
| Decaf coffee, 8 fl oz | 2 to 15 milligrams |
FDA notes that the amount of caffeine in specific products, and container sizes, can vary, and suggests contacting the manufacturer if you have questions about a product. MedlinePlus makes the same point: the amount of caffeine in different drinks can vary a lot.
Caffeine in places you might not expect
Coffee, tea and chocolate are the obvious ones. FDA says energy or protein bars, ice cream, chewing gum, dietary supplements and over-the-counter medicines are some of the products that may have caffeine as an added ingredient. MedlinePlus adds that some pain relievers, cold medicines, and over-the-counter medicines for alertness contain synthetic caffeine.
FDA says there’s no difference in the way your body handles or the safety between the caffeine that occurs naturally in coffee and tea and what’s added to a product, so count all of it.
Energy drinks deserve a closer look
FDA says that generally, energy drinks have 54 to 328 milligrams of caffeine per 16 fluid ounces, and that the FDA does not have a regulation specific to “energy drinks”. One large can can take up a big share of a 400 mg day.
The CDC notes that in addition to added sugar, these products may also contain large amounts of caffeine and other legal stimulants, and that concerns have been raised about their potential health risks, especially for young people. MedlinePlus warns that it is dangerous to combine alcohol and caffeine, because caffeine can interfere with your ability to recognize how drunk you are. Sugar is the other half of the story; our guide to sugary drinks covers what to check.
Steer clear of pure or highly concentrated caffeine products. FDA estimates that toxic effects, like seizures, can be observed with rapid consumption of around 1,200 milligrams of caffeine, or less than 1/2 teaspoon of pure caffeine.
Signs you’ve had too much
FDA lists these symptoms of too much caffeine:
- Increased heart rate or heart palpitations
- High blood pressure
- Insomnia or sleep disruptions
- Anxiety or jitters
- Upset stomach or nausea
- Headache
MedlinePlus adds restlessness and shakiness, dizziness, dehydration and dependency, meaning you need more to get the same results. It also says you may continue to feel the effects of caffeine for four to six hours, so an afternoon cup can linger into the evening. If you have any of these symptoms, FDA says to talk with your health care professional about your caffeine consumption.
Who should ask about a lower limit
Reading labels and cutting back
FDA explains what the package will and won’t tell you. All packaged foods are required to list caffeine in the “list of ingredients” when it is added to products as a stand-alone ingredient, but when caffeine comes from an ingredient such as chocolate, only that ingredient appears. Many products voluntarily list how much caffeine they contain, while restaurants are not required by law to tell you how much caffeine is in the products they serve, so ask. Our guide on how to read a nutrition label covers the rest of the panel.
If you want to cut back, FDA says it’s best to do so gradually. Swapping one cup for water or a decaf version is an easy first step, and our hydration basics guide has ideas for drinking more water. More drink guides are in the Drinks & Hydration hub.
Caffeine check-in checklist
- List every caffeinated drink, snack and medicine you have on a typical day
- Note your cup sizes, not just the number of cups
- Read ingredient lists for caffeine and check labels for the amount
- Ask how much caffeine is in coffee-shop and restaurant drinks
- Leave space between your last caffeinated drink and bedtime
- Talk to your provider if you’re pregnant, breastfeeding, have a heart condition or take regular medicines
- Cut back gradually if you decide to drink less
Frequently asked questions
Is 400 mg of caffeine a day safe for everyone?
No. FDA cites 400 milligrams a day for most adults and says there is wide variation in how sensitive people are and how fast they clear caffeine. Body weight, medicines, certain medical conditions and individual sensitivity all change what counts as too much for you.
Does decaf coffee have caffeine?
Yes, a little. FDA says decaf coffee typically has 2 to 15 milligrams in an 8-fluid-ounce cup. If you react strongly to caffeine in a negative way, FDA says you may want to avoid decaf drinks altogether.
Can kids and teens have energy drinks?
Medical experts advise against it. FDA reports that experts advise against energy drinks for children and teens because of the levels of sugar and caffeine, citing the American Academy of Pediatrics. Talk with your child's health care professional about any caffeine they have.
What happens if I cut back on caffeine suddenly?
You may get withdrawal. MedlinePlus lists headaches, drowsiness, irritability, nausea and trouble concentrating, which usually go away after a couple of days. FDA says that if you want to cut back, it's best to do so gradually.