How Much Caffeine is Okay to Consume?

Patient Presentation
A 17-year-old male came to clinic for his sports physical. He was doing well in school and had many friends. He denied any substance use, but did say that he had been using more energy drinks to help him with his weight training program and to stay awake longer at night so he could do his homework. The past medical history showed a healthy teen who had several sprained ankles because of athletics but no head injuries. The family history was positive for attention deficit disorder. The review of systems was negative.

The pertinent physical exam showed a healthy boy with growth parameters in the 50-75%. His examination was negative. The diagnosis of a healthy male was made. The pediatrician discussed with him the reasons for using the energy drinks. He noted that there are many other substances in the energy drinks that could also cause problems and didn’t recommend them or any other dietary supplements. “You are better off following a consistent weight training program and eating a variety of good foods than using the energy drinks or supplements,” he noted. “Let’s talk a bit about where and when you study and also about what you are eating and drinking. Maybe we can find a better combination of food, fluid and sleep that will keep you alert to do your homework too.”

Caffeine is a natural alkaloid found in more than 60 plants and is the most, or one of the most, ingested bioactive substances in the world. It is ingested most commonly in beverages (coffee, tea, soft drinks, energy drinks, caffeinated water or alcohol) but is also found in foods, medications, dietary supplements and over-the-counter stimulants. In the US coffee is the major source for adults. The concentration of caffeine depends on many factors such as the coffee species, agricultural practices, drying and storage of the beans, and the roasting, grinding and brewing of the coffee. In the US children ingest caffeine most often in tea and soft drinks. While the overall amount of caffeine intake is generally stable or declining, the use of energy drinks and coffee is increasing especially in the teenage population. The American Academy of Pediatrics recommends that children and teens do not consume energy drinks.

Caffeine impacts on the developing brain are not really known. Teens and children metabolize caffeine faster than adults. Caffeine is absorbed into the circulation usually within 30-45 minutes with peak plasma concentrations at 1-1.5 hours. It is excreted in the renal system but is also resorbed there. Caffeine is mainly metabolized by the cytochrome P450 system of the liver. The half-life is increased in females, pregnancy, preterm neonates, oral contraceptives and other medications, cigarette smoking and liver disease.

Caffeine use has pros and cons, which are listed below:

  • Pros
    • Alertness and attention
    • Concentration
    • Memory consolidation
    • Liver function improvement
    • Weight loss, possible
    • Cancer risk decreased for colorectal, endometrial, liver and prostate
    • Neurological disease risk decreased for Alzheimer’s and Parkinson’s diseases
    • Mortality may be improved with chronic use
  • Cons
    • Alcohol use, increased
    • Anxiety
    • Arrhythmias
    • Bone mineral absorption impaired
    • Death with overdose
    • Diuresis
    • Headache
    • Hypertension
    • Lethargy
    • Restlessness and jitteriness
    • Seizures
    • Sleep, especially inadequate amounts
  • Conflicting Data
    • Diabetes, Type II has decreased risk but other data shows impaired glucose tolerance
    • Cardiovascular, cholesterol and blood pressure problems but other compounds in coffee may have beneficial effects

In caffeine containing foods and beverages there are also other substances which people may have sensitivities to and can have potentially exaggerated responses. People may also mix different foods, beverages and medications which can also cause exaggerated responses. Some of the data is hard to separate out because of concurrent behaviors (e.g. increased alcohol use and caffeine use often occur together) or are intentionally linked. For example, caffeine is used to increase alertness and stave off sleep. This often means that sleep duration is decreased and the quality may be poor. So it can be hard to determine if poor sleep is a separate negative problem caused by caffeine.

Caffeine is prescribed medically for a variety of problems including apnea of prematurity, central nervous system respiratory depression, and migraine headache. Caffeine also causes bronchodilitation and is a derivative of theophylline which can be used for asthma. Pure caffeine is marketed directly to consumers and the US Food and Drug Administration (FDA) notes that at least 2 deaths have occurred because of its use and recommends avoiding these products. The FDA notes that, “A single teaspoon of pure caffeine is roughly equivalent to the amount in 25 cups of coffee.” The FDA does regulate caffeine as a food additive and considers it generally recognized as safe for its intended use specifically with cola-type beverages. The FDA does not require caffeine listed on nutrition food labels because it is not a nutrient. The caffeine concentration is required only on certain dietary supplement labels, but not all of them.

The amounts of caffeine found in common foods and beverages can be found here.

Learning Point
Suggested amounts of caffeine that are generally recognized as safe to consume per day by Health Canada.

  • Children (4-6 years) – < 45 mg/day
  • Children (7-9 years) – < 62.5 mg/day
  • Children (10-12 years) – < 85 mg/day
  • Teens (> 13 years) < 2.5 mg/kg or 100-175 mg/day
  • Adults – < 400 mg/day
  • Pregnancy and Breastfeeding Women- < 300 mg/day

Questions for Further Discussion
1. How much caffeine do you usually consume yourself and why do you consume it?
2. What are the risk factors for caffeine addiction?
3. What are the symptoms of caffeine withdrawal?

Related Cases

To Learn More
To view pediatric review articles on this topic from the past year check PubMed.

Evidence-based medicine information on this topic can be found at, the National Guideline Clearinghouse and the Cochrane Database of Systematic Reviews.

Information prescriptions for patients can be found at MedlinePlus for this topic: Caffeine

To view current news articles on this topic check Google News.

To view images related to this topic check Google Images.

To view videos related to this topic check YouTube Videos.

Health Canada. Caffeine in Food. Available from the Internet at (rev. 2/16/2012, cited 10/19/15).

Gonzalez de Mejia E, Ramirez-Mares MV. Impact of caffeine and coffee on our health. Trends Endocrinol Metab. 2014 Oct;25(10):489-92.

Owens JA, Mindell J, Baylor A. Effect of energy drink and caffeinated beverage consumption on sleep, mood, and performance in children and adolescents. Nutr Rev. 2014 Oct;72 Suppl 1:65-71.

Rosenfeld LS, Mihalov JJ, Carlson SJ, Mattia A. Regulatory status of caffeine in the United States. Nutr Rev. 2014 Oct;72 Suppl 1:23-33.

Wesensten NJ. Legitimacy of concerns about caffeine and energy drink consumption. Nutr Rev. 2014 Oct;72 Suppl 1:78-86.

Carskadon MA, Tarokh L. Developmental changes in sleep biology and potential effects on adolescent behavior and caffeine use. Nutr Rev. 2014 Oct;72 Suppl 1:60-4.

Ahluwalia N, Herrick K. Caffeine intake from food and beverage sources and trends among children and adolescents in the United States: review of national quantitative studies from 1999 to 2011. Adv Nutr. 2015 Jan 15;6(1):102-11.

US Food and Drug Administration. FDA Consumer Advice on Pure Powdered Caffeine. Medscape.
Available from the Internet at (rev. 9/1/15, cited 10/19/15).

Donna M. D’Alessandro, MD
Professor of Pediatrics, University of Iowa Children’s Hospital