Diarrhea, Constipation

Constipation refers to either going to the toilet less often, needing to empty the bowels, or passing hard, painful stools. It may be caused by not eating enough fiber, drinking enough fluids, a side effect of medications, or an underlying medical issue.1

Diarrhea is usually caused by fluid not being absorbed from the contents of the bowel, creating loose, watery stools. 2

Impact of coffee and caffeine on constipation

  • A cup of coffee may contain up to 100mg of caffeine
  • Caffeine is a stimulant, meaning it stimulates certain parts of the body, such as the brain, heart, and bowels
  • Stimulation of the bowels causes increased bowel movements and diarrhea.
  • However, more than 5 or 6 cups of coffee can cause constipation as it is a diuretic.


A cup of coffee could have up to 100mg of caffeine in it, and caffeine is a stimulant. As a stimulant, caffeine, and therefore coffee, will stimulate body parts like the brain, heart, and bowels. As the bowels are stimulated, bowel movements are increased, and can be looser. That is to say, coffee can cause diarrhea. However, if more than 5 or 6 cups of coffee are drunk, it can cause constipation. Caffeine, and therefore coffee, is a diuretic. This means you will pass more urine and lose more water from the body, becoming more dehydrated. This dehydration and lack of water in the body will make your stools harder and drier, causing constipation.3



              1 Patient - Constipation in Adults. Constipation symptoms and constipation relief        

         NHS Choices - Diarrhea - Causes

            3 Happy Bowel - Coffee and constipation link explained.