Whether you have to stay late at the office or pull an all-nighter for a project at school, drinks that contain caffeine may provide the energy boost you need to stay awake. Caffeine is a naturally occurring substance that works by stimulating your central nervous system. Though you may be able to safely consume approximately 200mg to 300mg of caffeine -- which is equivalent to about two cups of coffee -- on a dailiy basis, consuming more than 500mg to 600mg of caffeine each day may be poisonous to your body. Caffeine poisoning -- more commonly referred to as an overdose -- may cause unpleasant signs and symptoms, which should be reported to your doctor as soon as possible.
Insomnia
Typically, caffeine is utilized as a stimulant to help keep you awake. If you take too much of this substance, you may have repeated difficulty falling asleep or staying asleep -- a symptom of caffeine overdose called insomnia. Insomnia may also cause daytime sleepiness and may limit your ability to focus or remain attentive during work or school. Consult your medical provider if sleeping problems persist for more than a few days, as your insomnia may not be related to your caffeine intake.
Restlessness, Nervousness or Irritability
As a central nervous system stimulant, caffeine increases the transmission of nerve signals through your body. Consequently, you may feel unusually restless, nervous or jittery after consuming too much caffeine. Caffeine overdose may also cause mood changes, such as irritability or anxiety, MayoClinic.com explains.
Upset Stomach
Taking too much caffeine may irritate your stomach and may cause symptoms of diarrhea, nausea or vomiting, MedlinePlus explains. Diarrhea results in loose or watery bowel movements and may be accompanied by stomach pain or cramping. Contact your doctor as soon as possible if you continue to vomit or have diarrhea for more than a day or two. Vomiting and diarrhea cause your body to lose fluid, which may increase your risk of becoming dehydrated.
Abnormal Heart Rate or Muscle Tremors
Caffeine may also increase the rate at which your muscles contract -- especially when you consume this stimulant in excess. High levels of caffeine in your body may induce unusual muscle tremors or shakiness. You may also notice that your heart rate increases or becomes irregular. If you take extremely high doses of caffeine, heart rate changes may result in life-threatening medical complications. Seek care from your medical provider immediately if you notice changes in your heart rate or experience chest pain or breathing difficulties. Though these symptoms may be related to caffeine overdose, they may also be signs of a heart attack.
