The Symptoms of Too Much Caffeine

Starbucks coffee

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With caffeine in many different drinks, foods, and medications, you may find yourself experiencing the symptoms of caffeine overdose. Or, you may have a sensitivity to caffeine, even at low amounts. Learn the signs of these problems.


Caffeine is a naturally occurring stimulant found in coffee, tea, yerba mate, and chocolate (but not found in most herbal teas). Caffeine is also added to soft drinks, energy drinks, gum, and mints, among other foods. It is found in some medications used for pain relief as well as sold in energy tablets or powders. Caffeine is a common ingredient in herbal weight loss supplements, yet researchers say it may not be accurately reflected on the label.

How Much Caffeine Is Too Much

In moderation, caffeine is usually a very safe stimulant that can provide benefits such as alertness and improved mood, but too much caffeine consumption can cause a range of side effects. According to the FDA, you can consume up to 400 milligrams a day—that's about four or five small cups of coffee—with no dangerous side effects. However, people vary in how sensitive they are to caffeine and how fast they metabolize it.

Some people are sensitive to caffeine even at low levels. It’s also important to recognize that caffeine levels vary widely in coffee, tea, and other caffeine-containing substances. For example, the caffeine levels of Starbucks coffee drinks range from 10 milligrams to 415 milligrams.

Caffeine Overdose Symptoms in Adults

Caffeine overdose symptoms vary from person to person and range from moderate (flushed face) to extreme (death), depending on the individual and the level of caffeine consumption. Caffeine overdose symptoms include:

  • Accelerated heartbeat
  • Anxiety and other nervous system issues
  • Confusion
  • Diarrhea
  • Difficulty sleeping, insomnia, restlessness, or issues with passing in and out of consciousness
  • Dizziness
  • Fever
  • Flushed face
  • Gastrointestinal problems
  • Hallucinations and other nervous system symptoms
  • Headaches
  • Increased urination
  • Increased thirst
  • Irregular heartbeat
  • Irritability
  • Jitteriness
  • Muscle twitching/spasms or convulsions
  • Nausea
  • Respiratory problems
  • Vomiting
  • Death

Death by caffeine alone is extremely rare and is often intentional. It would take around 10,000 milligrams of caffeine (about 100 cups of brewed coffee) to kill someone who weighs 150 pounds. However, caffeine may interact with other medications or alcohol and can pose a problem for those with underlying conditions.

Caffeine During Pregnancy, While Nursing, and for Children

Caffeine can be transferred to the fetus during pregnancy and experts say it's prudent to limit caffeine intake to 200 mg/day or less when trying to conceive a child and during pregnancy. A small amount of caffeine is transferred into breast milk, but it usually does not adversely affect the infant when the mother consumes low to moderate amounts (up to 300 mg per day). The American Academy of Pediatrics recommends that children under the age of 12 years should not eat or drink any caffeine-containing foods or drinks. While you may not be giving your child coffee, be aware of the other sources such as sodas, chocolate, and energy drinks. 

Caffeine Sensitivity

Symptoms of caffeine sensitivity are similar to symptoms of caffeine overdose, but they may begin at much lower levels of caffeine consumption, such as the relatively low level of caffeine in a chocolate bar.

Factors influencing caffeine sensitivity include:

  • Age: Children are more sensitive to caffeine than adults. Older adults also have an increasing degree of caffeine sensitivity.
  • Biological sex: Women are sometimes more sensitive to caffeine than men.
  • Health issues: Anxiety, cardiovascular problems, or respiratory problems may increase susceptibility to caffeine sensitivity and overdose.
  • Irregular caffeine consumption: Regular caffeine consumption increases most people's caffeine tolerances, but if you have it rarely you will feel the effects more.
  • Medications: Caffeine can interact with drugs and supplements such as theophylline, echinacea, and certain antibiotics such as ciprofloxacin and Noroxin (norfloxacin). Potential side effects include amplification of the symptoms associated with excess caffeine consumption and prolonged effects of caffeine.
  • Weight: Lower weight usually increases caffeine sensitivity.

If you are experiencing caffeine sensitivity symptoms, you may want to talk with your doctor about your symptoms and any factors that may increase your caffeine sensitivity to determine safe levels of caffeine consumption.

Reducing or Treating Symptoms From Too Much Caffeine

If you are experiencing serious caffeine overdose symptoms (such as heart palpitations in conjunction with pre-existing cardiovascular issues), immediately contact poison control or your local emergency services.

If you are experiencing milder caffeine symptoms (such as jitteriness or restlessness), talk with your doctor or reduce your caffeine consumption level.

If you want to cut down on caffeine consumption, you can avoid some caffeine withdrawal symptoms by cutting back slowly. If coffee is your caffeine vice, cutting back your caffeine intake by half a cup per day is generally recommended.

Article Sources
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