Caffeine Side Effects

Learn about caffeine side effects

Caffeine affects each of us differently. Our caffeine side effects will vary – depending on our size and how our body reacts to the caffeine. Each one of us is unique, so some will experience more caffeine side effects than others. A mild dose of caffeine takes about half an hour to an hour to kick in and the effects will wear off after about four hours. It is interesting to know how caffeine works in our body.

General Side Effects

Here are some of the reported side effects of caffeine when taken in moderation:
  • Caffeine stimulates the heart, central nervous system and respiratory system – but it can ultimately cause drowsiness, anxiety, confusion and irritability.
  • Raises blood pressure.
  • Causes the stomach to produce more acid.
  • Irritates the stomach lining which can cause nausea and cramps and can even lead to stomach ulcers.
  • Hinders digestion by relaxing the intestinal muscles.
  • Makes your blood thicker.
  • Hardens the arteries, making blood vessels thicker.
  • Dehydrates the body – this is because caffeine is a diuretic.
  • Interferes with having a good night sleep. This is because the nervous system is too stimulated to allow deep restful sleep. See my page on how does caffeine work.
  • Interferes with calcium absorption, increasing the risk of osteoporosis.
  • Can cause one to feel dizzy and very jittery with shaking hands and legs and palpitations…I can vouch for this one!

Caffeine Intoxication

Drinking too much caffeine in a short space of time – usually more than 300mg or 3 cups of coffee - will result in caffeine intoxication, also called caffeine jitters. This amount varies from person to person depending on body weight and level of caffeine tolerance. It is interesting to not that the symptoms of caffeine intoxication are not unlike overdoses of other stimulants.
The symptoms for this disorder may include:
  • irritability
  • anxiety
  • restlessness
  • confusion
  • headache
  • insomnia
  • caffeine side effects

  • muscle tremors
  • muscle twitching
  • rapid breathing
  • frequent urination
  • ringing in the ears
  • seeing flashes of light
  • increase in skin sensitivity
  • abdominal pain
  • nausea
  • vomiting
  • dehydration
  • fever


When we consume large amounts of caffeine over a long period of time, it can lead to caffeinism, which is a condition that is the combination of caffeine dependency and a wide range of very unpleasant mental and physical conditions listed below:
  • anxietynervousness
  • irritability
  • insomnia
  • headaches
  • heart palpitations
  • muscle tremors
  • muscle twitching
  • stomach ulcers
  • acid reflux disease
  • inflammation of the oesophagus

Given up on Caffeine?

Have you had to give up caffeinated drinks for health reasons or simply out of choice?

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housewife - caffeine effects Not rated yet
I was operated for liver cancer 6 years ago and since then I can not drink caffenated tea which I love or coffee. If I do I am up to 4 or 5 pm. If I keep …

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I suffered from severe heartburn as I drank a lot of coffee. Then my daughter,who is a pharmacist told me that caffeine dialates the sphincter muscle …

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