Notes

1. Increased Heartbeat 
Caffeine acts as a stimulant on the central nervous system, increasing your heart rate. This can be expected as soon as 15 minutes after ingesting.
Energy drinks: health risks and toxicity

2. Heartburn/Reflux
Caffeine has been shown to relax the esophagus, contributing to gastroesophageal reflux. This can either cause or exacerbate heartburn in susceptible individuals.
Neuropsychiatric effects of caffeine

3. Jitters/Restlessness
Caffeine stimulates hormones, such as adrenaline, sending your body into jitters and tremors.


4. Anxiety
The stimulant effects on the body from caffeine, such as increased heart rate, increased adrenaline hormones, and heightened senses, can combine to produce an overwhelming sensation in some people, making them feel anxious.

5. Muscle Twitches and Spasms
A high volume or prolonged use of caffeine in the body can cause the muscles to cramp or move erratically.


6. Rambling Thought and Speech
Along with many of your other senses, speech and thought speed up in response to the stimulant effect of caffeine. While this can be very useful for concentration, too much can cause confusion and stuttering.


7. Heart Palpitations
Caffeine stimulates the central nervous system. It speeds up the heart rate and can cause the heart to flutter or palpitate.


8. Diuresis
Caffeine increases the need to urinate because it increases blood flow through the kidneys and dilates the blood vessels, making the kidneys produce more waste.


9. Gastrointestinal Disturbance
Caffeine acts like a laxative by increasing contraction in the small and large intestinal muscles. This can cause predigested food to move into the intestine, triggering stomach cramps.


10. Dehydration
Persistent diarrhea and urination can lead to dehydration, which can upset the body’s fluid balance, depleting it of the water, vitamins, and minerals it needs to order to function.


11. Insomnia
Caffeine inhibits the activity of a neurotransmitter called Adenosine, which is one of your brain’s natural tranquilizers. It puts you to sleep when levels are high enough. By inhibiting Adenosine activity, caffeine inhibits your ability to fall asleep.


12. Headaches
The combination of diuretic and stimulant pulsing through the body can cause the receptors in the brain to become overloaded, leading to a headache.


13. Hallucinations
Hallucinations are believed to occur when an overdose of caffeine causes the body to become stressed. This is a result of high adrenaline

14. Addiction
Caffeine addiction or dependence begins because caffeine first creates the alert feeling that coffee drinkers crave, and later becomes a chemical that the body needs to prevent withdrawal symptoms such as headaches, lethargy, and depression.
A critical review of caffeine withdrawal: empirical validation of symptoms and signs, incidents, severity and associated features

15. Increased Blood Pressure
Caffeine causes your adrenal glands to release more adrenaline, which causes your blood pressure to increase.