Harmful Effects of Caffeine

Caffeine is a substance found in many beverages such as colas, coffee, tea, some plants, chocolate and many medications. Caffeine stimulates the central nervous system and can affect the body’s metabolism in several ways. According to John Hopkins Medical Center, caffeine is the most widely abused mood-altering drug in the world and that between 80 and 90 percent of all children and adults in North America habitually consume it. Caffeine can have desirable effects in small doses such as increased energy, alertness and metabolism, but in larger doses there are side effects that can be harmful.

Heart Rate

One potentially harmful effect of caffeine intake is its affect on the heart muscle. Through a complicated series of reactions, caffeine mimics the effects of epinephrine and increases the contractibility of heart muscle cells. This increases the heart rate or pulse. The American Heart Association reports that while caffeine does temporarily increase blood pressure, studies show that there is no detectable link between caffeine and high blood pressure.


Caffeine can cause increased anxiety and induce panic attacks when large amounts are ingested, according to the National Institutes of Health. Those who are susceptible to anxiety and panic attacks should limit caffeine intake as it can exacerbate their problem.

Sleep Disruption

According to Caffeinedependence.org, caffeine causes sleep deprivation by delaying the onset of sleep, decreasing the total amount of sleep and can disrupt the normal patterns or stages of sleep. Again, some individuals are more sensitive to the effects of caffeine and will have more sleep disruption than others, but even in individuals who have a high tolerance, large amounts of caffeine throughout the day or caffeine ingested just before bedtime is likely to cause sleep deprivation.


Caffeine can be addictive for those who regularly ingest large amounts of it. One common symptom of a physical dependence upon caffeine is the onset of headaches when caffeine consumption has decreased or temporarily stopped. According to the Mayo Clinic, headaches are possible for those who consume 500 mg or more per day, the equivalent of about five cups of coffee.


Especially for those who are sensitive to caffeine or who do not regularly use it, caffeine can cause irritability, muscle tremors, nervousness and restlessness, which can affect your ability to function properly throughout the day. Some factors that may affect how easily caffeine causes these effects are your level of stress, your body mass, your age and your overall health.

About this Author

Dr. Blake Biddulph received his chiropractic degree from Parker College of Chiropractic in Dallas in 2007 and has been practicing as a chiropractic physician in Provo, Utah, ever since. He has a special interest in spinal rehabilitation and treats patients with a variety of neck and back conditions. He has been writing health-related articles and newsletters for several years.