Caffeine: How much is too much?

Caffeine has its perks, but it can pose problems too. Find out how much is too much and if you need to curb your consumption.

By Mayo Clinic Staff

If you rely on caffeine to wake you up and keep you going, you aren't alone. Millions of people rely on caffeine every day to stay alert and improve concentration.

How much is too much?

Up to 400 milligrams (mg) of caffeine a day appears to be safe for most healthy adults. That's roughly the amount of caffeine in four cups of brewed coffee, 10 cans of cola or two "energy shot" drinks. Keep in mind that the actual caffeine content in beverages varies widely, especially among energy drinks.

Caffeine in powder or liquid form can provide toxic levels of caffeine, the U.S. Food and Drug Administration has cautioned. Just one teaspoon of powdered caffeine is equivalent to about 28 cups of coffee. Such high levels of caffeine can cause serious health problems and possibly death.

Although caffeine use may be safe for adults, it's not a good idea for children. Adolescents and young adults need to be cautioned about excessive caffeine intake and mixing caffeine with alcohol and other drugs.

Women who are pregnant or who are trying to become pregnant and those who are breast-feeding should talk with their doctors about limiting caffeine use to less than 200 mg daily.

Even among adults, heavy caffeine use can cause unpleasant side effects. And caffeine may not be a good choice for people who are highly sensitive to its effects or who take certain medications.

Read on to see if you may need to curb your caffeine routine.

You drink more than 4 cups of coffee a day

You may want to cut back if you're drinking more than 4 cups of caffeinated coffee a day (or the equivalent) and you're experiencing side effects such as:

  • Migraine headache
  • Insomnia
  • Nervousness
  • Irritability
  • Restlessness
  • Frequent urination or inability to control urination
  • Stomach upset
  • Fast heartbeat
  • Muscle tremors

Even a little makes you jittery

Some people are more sensitive to caffeine than are others. If you're susceptible to the effects of caffeine, even small amounts may prompt unwanted effects, such as restlessness and sleep problems.

How you react to caffeine may be determined in part by how much caffeine you're used to drinking. People who don't regularly drink caffeine tend to be more sensitive to its effects.

You're not getting enough sleep

Caffeine, even in the afternoon, can interfere with your sleep. Even small amounts of sleep loss can add up and disturb your daytime alertness and performance.

Using caffeine to mask sleep deprivation can create an unwelcome cycle. For example, you may drink caffeinated beverages because you have trouble staying awake during the day. But the caffeine keeps you from falling asleep at night, shortening the length of time you sleep.

You're taking medications or supplements

Certain medications and herbal supplements may interact with caffeine. Examples include:

  • Ephedrine. Mixing caffeine with this medication — which is used in decongestants — might increase your risk of high blood pressure, heart attack, stroke or seizure.
  • Theophylline (Theo-24, Elixophyllin, others). This medication, used to open up bronchial airways, tends to have some caffeine-like effects. So taking it with caffeine might increase the adverse effects of caffeine, such as nausea and heart palpitations.
  • Echinacea. This herbal supplement, which is sometimes used to prevent colds or other infections, may increase the concentration of caffeine in your blood and may increase caffeine's unpleasant effects.

Talk to your doctor or pharmacist about whether caffeine might affect your medications.

Curbing your caffeine habit

Whether it's for one of the reasons above or because you want to trim your spending on coffee drinks, cutting back on caffeine can be challenging. An abrupt decrease in caffeine may cause withdrawal symptoms, such as headaches, fatigue, irritability and difficulty focusing on tasks. Fortunately, these symptoms are usually mild and get better after a few days.

To change your caffeine habit, try these tips:

  • Keep tabs. Start paying attention to how much caffeine you're getting from foods and beverages, including energy drinks. Read labels carefully. But remember that your estimate may be a little low because some foods or drinks that contain caffeine don't list it.
  • Cut back gradually. For example, drink one fewer can of soda or drink a smaller cup of coffee each day. Or avoid drinking caffeinated beverages late in the day. This will help your body get used to the lower levels of caffeine and lessen potential withdrawal effects.
  • Go decaf. Most decaffeinated beverages look and taste much the same as their caffeinated counterparts.
  • Shorten the brew time or go herbal. When making tea, brew it for less time. This cuts down on its caffeine content. Or choose herbal teas that don't have caffeine.
  • Check the bottle. Some over-the-counter pain relievers contain caffeine. Look for caffeine-free pain relievers instead.

The bottom line

If you're like most adults, caffeine is a part of your daily routine. Usually, it won't pose a health problem. But be mindful of caffeine's possible side effects and be ready to cut back if necessary.

March 06, 2020 See more In-depth

See also

  1. Healthy-eating habits
  2. Reduce sugar in your diet
  3. Acai berries
  4. Alcohol use
  5. Alkaline water
  6. Artificial sweeteners and other sugar substitutes
  7. Autism spectrum disorder and digestive symptoms
  8. 2015-2020 Dietary guidelines
  9. Breast-feeding nutrition: Tips for moms
  10. Is caffeine dehydrating?
  11. Calorie calculator
  12. The role of diet and exercise in preventing Alzheimer's disease
  13. Can whole-grain foods lower blood pressure?
  14. Chart of high-fiber foods
  15. Cholesterol: Top foods to improve your numbers
  16. Coconut water: Healthy drink or marketing scam?
  17. Coffee and health
  18. Diet soda: How much is too much?
  19. Dietary fats
  20. Dietary fiber
  21. Prickly pear cactus
  22. Does soy really affect breast cancer risk?
  23. Don't get tricked by these 3 heart-health myths
  24. Make healthy snack choices
  25. Eat more of these key nutrients
  26. Energy drinks
  27. Fat grams
  28. Fiber: Soluble or insoluble?
  29. Fish and polychlorinated biphenyls (PCBs)
  30. Fit more fiber into your diet
  31. Grape juice health benefits
  32. Guidelines for a good ileostomy diet
  33. Is chocolate healthy?
  34. High-fructose corn syrup
  35. High-protein diets
  36. Alcohol during the holidays: 4 ways to sip smarter
  37. Holiday weight: How to maintain, not gain
  38. How the right diet can help an overactive bladder
  39. Takeout containers
  40. Juicing
  41. Depression and diet
  42. Limit bad fats, one step at a time
  43. Make food labels required reading
  44. Monosodium glutamate (MSG)
  45. MUFAs
  46. Nutrition Facts label
  47. Nutrition rules that will fuel your workout
  48. Omega-3 in fish
  49. Omega-6 fatty acids
  50. Phenylalanine
  51. Protein: Heart-healthy sources
  52. Raw water: Risky fad?
  53. Reduce sugar in your diet
  54. Health foods
  55. Portion control
  56. Planning healthy meals
  57. High-fiber diet
  58. Social eating can be healthy and enjoyable
  59. Sodium
  60. Tap water or bottled water: Which is better?
  61. Taurine in energy drinks
  62. The best foods for healthy skin
  63. Time to cut back on caffeine?
  64. Time to scale back on salt?
  65. Trans fat
  66. Underweight: Add pounds healthfully
  67. Daily water requirement
  68. What is clean eating?
  69. What's the difference between juicing and blending?
  70. Why does diet matter after bariatric surgery?
  71. Working out? Remember to drink up
  72. Yerba mate