Caffeine Pros and Cons

The Truth About Caffeine

Good or Bad?


JavaBeansThe media sends out mixed messages about caffeine.   One day, deaths are blamed on caffeinated energy drinks.  The next, coffee is found to decrease risk for diabetes.  Like anything in life, the truth is neither black nor white.  Arming yourself with information can guide you towards decisions that best meet your needs and lifestyle.

How Much Caffeine Is In Food and Drink?

Caffeine is not limited to beverages but is found in foods and as ingredients in certain over-the-counter medications.  If you are sensitive to caffeine, you should read product labels carefully.  The caveat here is that caffeine from natural ingredients such as green tea is often not calculated into the final tally on product labels.  The end result is that you may take in more caffeine than is reported.

The Food and Drug Administration (FDA) regulates that no more than 0.02% of caffeine be directly added to a product.  This means that any product manufactured with caffeine must have 0.02% or less of the substance in the product to be considered safe.  For example, a 12 oz drink can have 71 mg of caffeine and meet the 0.02% limit.

In order for a product to be labelled decaffeinated, the FDA regulates that 97.5% of the caffeine must be removed.  The problem with this is the variation in available products.  There has not been consistency in the marketplace and this has been documented in  multiple studies.  Variations may be attributable to random production error or even in user preparation.  For example, if a restaurant prepares “decaff” coffee but adds more ground coffee to less water, the final product will be more concentrated and may not meet the threshold for a true “decaff” product.

This has led to the development of caffeine-testing strips for consumers.  Available at most grocery stores or on-line retailers,  these test strips average 98% accuracy when used according to directions.  The strips are not effective in the presence of sugar and milk, and if you choose to use these strips, you should add your own milk or sugar AFTER testing.  “Decaff” coffee should have less than 10mg of caffeine per 6 oz serving.

In some cases, the caffeine content has been found to be well over 30 mg!  For someone who is sensitive to caffeine, this can be significant.

See Caffeine in Food and Drink.

What Are the Benefits of Caffeine?

Ask any coffee drinker about the benefits of their cup o’ Joe and you will hear about the big three:

  1. Alertness
  2. Concentration
  3. Energy

These effects are commonly achieved at caffeine levels around 100mg-200mg daily.

There have been benefits of caffeine reported in small clinical studies, but more data and larger studies are needed to establish true cause and effect relationships.  For example, these studies may be monitoring caffeine intake via coffee or other caffeinated beverages such as tea.  There may be something inherent in those beverages or some combination of elements promoting those health benefits.

  • Improved asthma symptoms
  • Improved exercise performance when taken immediately prior to exercise
  • Improved immune function (via caffeine’s anti-inflammatory effects)
  • Improved memory
  • Reduced intensity of allergic reactions (via caffeine’s reduction of histamine levels)
  • Reduced risk for diabetes
  • Reduced risk for colon cancer
  • Reduced risk for dementia
  • Reduced risk for liver disease
  • Reduced risk for Parkinson’s disease
  • Treatment of migraine headaches

What Are the Harms of Caffeine?

Caffeine has dose-related effects on the body.

SAFE LEVELS (< 300mg per day) ADVERSE EFFECTS (300mg – 500mg per day) TOXIC LEVELS (> 500mg per day)
Generally well tolerated in the general population.
  • Anxiety
  • Insomnia
  • Irritability
  • Nausea
  • Nervousness
  • Palpitations
  • Restlessness
  • Tremors
  • Symptoms listed to the left

- AND-

  • Abdominal pain
  • Addiction
  • Hallucinations
  • Headache


Caffeine can have other negative effects on the body.

Breast disease: Caffeine can increase fibrocystic changes in the breast tissue.  This can increase breast pain and discomfort for many women.  It is believed that caffeine increases levels of stress hormones in the body that can then affect the reproductive hormones – estrogen and progesterone.  There has been no data to suggest that caffeine increases breast cancer rates.

Cardiovascular disease:

  • Mild temporary increases in blood pressure (up to 10 points after one to two 6 oz cups of coffee) and heart rate are common.
  • Palpitations, especially PVCs (premature ventricular contractions) may occur in individuals sensitive to caffeine’s effects.
  • Caffeine intake has been associated with elevations in C-reactive protein, a marker for inflammation associated with cardiac disease.
  • Caffeine has not been proven to directly increase cardiovascular disease, but it may increase risk for those with known underlying heart disease.


  • Caffeine at levels > 300mg daily may increase calcium and magnesium losses in the urine, risking decreased bone density and osteoporosis.
  • Calcium losses from caffeine can be counteracted if adequate amounts of calcium are eaten in the diet or taken as a supplement, especially for those older than 65 years of age (aim for 1200mg calcium daily).
  • Older individuals may be more sensitive to caffeine’s effects and at higher risk for secondary bone disease

Psychiatric illness:

  • Caffeine can precipitate anxiety, panic attacks, and psychosis in patient’s with underlying psychiatric disorders.
  • It can also increase the risk for manic episodes in bipolar (manic-depressive) patients.

How Much Caffeine Is Safe?

The FDA has reported five deaths related to caffeine in the past 3 years.  These deaths have been correlated with use of Monster Energy drinks.  One 24 oz of Monster Energy contains 240mg of caffeine.  Comparatively, one 12 oz Starbucks coffee has 260mg of caffeine.  That’s right, the same volume of Starbucks coffee more than double the caffeine than a single Monster Energy drink.  Have you ever heard of death by Starbucks?  No?  Then it must make you wonder why Monster Energy has become the target of recent media hype.

Caffeine reaches toxic levels at intakes >500mg per day (see above) and may be fatal above 3,000mg per day.  Effects of caffeine may be intensified by co-morbid intake of alcohol or as a result of drug-drug interactions.  This may be the correlation between use of Monster Energy and the reported deaths.  Investigations remain underway.

Use the calculator below to see how much caffeine would be fatal according to an individual’s weight.

See the Death by Caffeine Calculator

Does Caffeine Interfere With Medications?

Caffeine can have adverse effects (by impairing absorption or increasing drug concentrations in the blood stream) when used in combination with the following medications and supplements:

Antibiotics Psychiatric Medications Other Medications
  • Biaxin (Clarithomycin)
  • Cipro (Ciprofloxacin)
  • Erythromycin
  • Norfloxacin
  • Zithromax (Azithromycin)
  • Disulfiram
  • Fluvoxamine
  • Lithium
  • Olanzapine
  • Adenosine (cardiac)
  • Albuterol (asthma)
  • Cimetidine (antihistamine)
  • Echinacea (herbal)
  • Levothyroxine (thyroid)
  • Theophylline (asthma)
  • Vicodin (pain)


Most importantly, caffeine in combination with alcohol has heightened toxic effects, and this may be the culprit for deaths relating to caffeinated energy drinks.  The caffeine is likely to offset the sedating effects of the alcohol and this allows for higher volumes of both substances to be ingested.

How Long Does Caffeine Stay in the Body?

It is important to note what time of day caffeine is ingested so that effects on sleep can be minimized.  The half-life for caffeine is 5 to 7 hours.  This means that 5 to 7 hours after caffeine consumption half of the caffeine has been metabolized by the liver and is eliminated from the body.  For most people, one or two cups of coffee in the morning will not affect their sleep patterns later that evening.

Is It Dangerous To Abruptly Stop Caffeine?

Caffeine is a stimulant that affects the central nervous system.  It has mildly addictive properties and can lead to withdrawal symptoms for individuals who have daily caffeine uptake approximating 2 cups of coffee or more.  Symptoms of withdrawal include:

  • Anxiety
  • Concentration difficulty
  • Depressed mood
  • Headache
  • Irritability

Overall, it is annoying to withdraw from caffeine but not dangerous.

What Should You Do?

There is no reason to refrain from caffeine entirely unless you have specific risk factors as noted above.  If you do choose to ingest caffeine, be sure to do so within safe limits, generally aiming for less than 300mg daily.  You may need to decrease your caffeine intake if you are prescribed any of the medications noted above.   When in doubt, speak to your medical provider for guidance about your caffeine intake.

Related Medical News Today articles:

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3 thoughts on “Caffeine Pros and Cons”

  1. This is by far the best & up to date info I have read in a long while on Caffeine..all ‘tidied up’ in one nice spot-thanks, Dr!

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