At moderate levels, caffeine can boost your mood, increase your energy, stimulate your metabolism and even protect against some diseases. If you absorb too much caffeine, however, you can endanger or seriously harm your body. Remember that caffeine is a genuine drug that affects your body and mind, and hence it warrants mindful caution; abuse or overdose can hurt your nervous, digestive, respiratory and even cardiac systems.
Nervous System: Mild to Moderate Effects
If you absorb too much caffeine, your breathing, heart rate and blood flow may quicken. Physically, this effect can lead to higher blood pressure, dizziness, sweating, shaking and tremors. Mentally and emotionally, you may experience nervousness, jitteriness, irritability, anxiety, stress and agitation. Too much caffeine also affects your ability to sleep, causing restlessness, insomnia and sleep loss.
Nervous System: Moderate to Severe Effects
In more serious cases of caffeine overdose, you may experience trouble breathing, fever, vomiting and mental confusion or even hallucinations. Slight tremors may become convulsions, and your increased heart rate may lead to a dangerously rapid, slow or irregular heartbeat. At the extreme, these effects can cause cardiac arrest, coma and even death.
Because caffeine acts as a diuretic, absorbing too much caffeine will make you urinate excessively, which can lead to dehydration if you don’t drink enough water. A caffeine overdose can also cause mild to severe diarrhea, which exacerbates dehydration. Dehydration can cause weakness, dizziness, lethargy, skin problems, confusion and cardiac strain.
Stomach and Digestion
Caffeine increases the amount of stomach acid your body produces, which then affects your intestines as you digest foods and drinks. This can cause digestive problems and abdominal pains. To limit or prevent this problem, in addition to limiting your caffeine intake, don’t consume caffeine on an empty stomach.
Technically, caffeine does not cause addiction; however, you can become dependent on it, and it can become a physically ingrained habit. If you accustom your body to habitual caffeine intake, then your body begins to need it every day to function normally. You may feel better after your morning coffee, for example, simply because it calmed the caffeine withdrawal your body began experiencing through the night.
Over time, you can become desensitized to caffeine, and you may begin needing increasingly larger amounts to achieve the same energy boost, which can lead to harmfully high doses. If you stop habitual caffeine consumption, you may experience withdrawal symptoms, which can include headaches, tiredness, irritability, nausea and vomiting.
Safe and Dangerous Amounts
To avoid absorbing too much caffeine, limit your intake to a moderate level--200 to 250 milligrams per day. That amount of caffeine equals two or three cups of coffee, two espressos, three soda cans or two to four cups of caffeinated tea. Remember that chocolate and chocolate-based drinks contain caffeine, as do some pain killers and weight loss medications.
Your weight, genetics, lifestyle and caffeine habits influence your tolerance, but in general, more than 250 milligrams can cause some harmful effects. If you’re sensitive to caffeine, you may experience those effects at much lower doses. If you drink ten 8-oz. cups of coffee in one day, then you’re consuming an excessive and dangerous dose, warns MedlinePlus.
- University of Maryland Medical Center; Caffeine Overdose; 2011
- MedlinePlus; Caffeine in the diet; May 2009
- "Forensic Science International"; Fatal Caffeine Overdose: Two Reports; S. Kerrigan and T. Lindsey; October 2005
- "Medical Journal of Australia"; Cardiac Arrest in a Young Man Following Excess Consumption of Caffeinated "Energy Drinks"; A.J. Berger and K. Alford; January 2009
- Research Penn State; Is Caffeine Harmful to Your Health?; Lauren Clark and Byron Jones; October 2006