The coffee hit is an essential start to the day for millions of people around the world each morning.

Australians spent almost $800 million on over two billion cups of coffee last year – and that’s just the start of the caffeine habit.

But like all drugs, overuse of caffeine has risks.

Studies show more than 400mg per day can put a person at risk of adverse effects.

So after your double shot in the morning and your Coke with lunch, you may be doing more damage to your body than you realise.

Here are 20 dangers of partial and total caffeine overdose, in order from the first symptoms to be exhibited to the severe, later stage ones.

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.
Energy drinks: health risks and toxicity

4. Anxiety
The stimulant effect on the body form caffeine such as increased heart rate, increased adrenaline hormones and heightened senses, can cause an overwhelming sensation in some people causing them feel anxious.
Neuropsychiatric effects of caffeine

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

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

7. Heart palpitations
Caffeine stimulates the central nervous system, it speeds up the heart rate and cause the heart to flutter or palpitate.
Energy drinks: health risks and toxicity

8. Diuresis
Caffeine increases the need to urinate because it increases blood flow through the kidneys and dilates the blood vessels hence making the kidneys produce more waste.
Neuropsychiatric effects of caffeine

9. Gastrointestinal disturbance
Caffeine acts like a laxative, by increasing contraction in the small and large intestinal muscles. This can cause pre-digested food to move into the intestine, triggering stomach cramps.
Energy drinks: health risks and toxicity

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.
Neuropsychiatric effects of caffeine

11. Insomnia
Caffeine inhibits the activity of a neurotransmitter called Adenosine. Adenosine 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.
Energy drinks: health risks and toxicity

12. Headaches
The combination of diuretic and stimulant pulsing through the body causes the receptors in the brain to become overloaded and leads to a headache.
Energy drinks: health risks and toxicity

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 levels and stimulant.
Energy Drinks and the Neurophysiological Impact of Caffeine

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

15. Increase Blood Pressure
Caffeine causes your adrenal glands to release more adrenaline, which causes your blood pressure to increase.
Energy drinks: health risks and toxicity

16. Stomach Ulcers
Caffeine speeds up the process of gastric emptying, which may result in highly acidic stomach contents passing into the small intestine more rapidly than normal causing injury or ulcers.
Effects Of Caffeine And Coffee On Heartburn, Acid Reflux, Ulcers And GERD

17. Cardiac arrest
An increased blood pressure from high caffeine intake and the effects of the stimulant on the cardio-vascular system can have a devastating outcome for people with weak hearts.
Caffeine Intake in Relation to the Risk of Primary Cardiac Arrest

18. Coma
When a person consumes too much caffeine, they go into what is known as caffeine intoxication where they become confused and disoriented. This is when a caffeine coma can occur, as well as seizures.
Tachycardia, Intoxication, and Coma: The Physiological Effects of Caffeine on Daphnia magna and Humans

19. Death
People with caffeine sensitivities can died from caffeine overdose. While achieving a lethal dose of caffeine would be difficult with regular coffee, high doses with caffeine pills are a known cause of many caffeine overdoses.
Massive caffeine ingestion resulting in death