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Lactose intolerance is a condition that comes on when there is a lack of lactase production. Lactase is an important enzyme responsible for breaking down lactose. In infants, it’s especially important to break down the lactose in breast milk, but as children grow up, generally they produce less and less lactase – so much so that by adulthood, up to 70% of people no longer produce enough lactase to properly digest lactose in milk, which leads to symptoms appearing when they eat or drink dairy.

Lactose Intolerance affects up to 70% of people worldwide. In some cases, it can even start suddenly, regardless of if you have had issues with dairy products before. Here are the common symptoms to look out for, which usually start half an hour to two hours after eating or drinking something containing lactose.

  1. Stomach bloating and pain

This is one of the most common symptoms of lactose intolerance. This happens as a result of your body being unable to break down lactose, passing it through the gut and into the colon. Lactose is a carbohydrate that cannot be absorbed by the cells that line the colon and is instead fermented by the microflora (naturally occurring bacteria that live there) which then releases gas. This gas leads to stomach pain, usually found in the lower half of the stomach.

  • Diarrhoea

Lactose intolerance causes diarrhoea as it increases the volume of water in the colon.

  • Constipation

This tends to be much rarer than diarrhoea and is not commonly associated with lactose intolerance but has been reported as a symptom.

Rarer symptoms:

  • Headaches
  • Fatigue
  • Muscles and joint pain
  • Problem’s urinating
  • Loss of concentration
  • Eczema
  • Mouth ulcers

Obviously, all these symptoms are not exclusive to lactose intolerance so its very important to make an appointment with your doctor so they can find out what is wrong! Also, it’s important to remember that sometimes there may be no symptoms present at all!


If diagnosed with lactose intolerance, its quite likely that one of the major treatments will be a restriction or complete avoidance of high-lactose foods, like milk, cheese, cream, and ice cream. That’s not to say that you will have to cut out dairy completely, as some people can handle certain amounts – but that is for your doctor to advise.

My name is Emma, and I'm originally from the north west of Ireland! I'm a journalism student in DCU, and have loved reading and writing ever since I was young. I'm a big lover of music, and also do some modelling work on the side!
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