Common Allergy and Intolerance Symptoms

Allergies and Intolerances can induce a range of symptoms, making them difficult to detect. Additionally, a trigger food for one person may provoke completely different reactions in someone else. Items like gluten, dairy, nuts and pet hair are common issues. Here listed are the most common reactions, along with symptoms they can portray.


Bloating is a common symptom of food intolerances. Defined as swelling or distension in the abdomen, it can mean visible distension for some, but others experience the sensation without any visible physical change. As bloating is contained to the digestive system, it’s often linked with excessive wind (eructation and flatulence) and discomfort.

Bloating can stem from various imbalances within the body, a common one being a food allergy or intolerance. Symptoms may also arise as a side effect from dehydration, anxiety, stress, and pregnancy.

Other causes are:

  Abnormal intestinal contractions


  Lacking nutrients (or struggling to absorb them)

  Bacteria imbalance

  Nerve damage


Constipation is where you find it difficult to pass stools, or they become painful to pass. The increased excrement in your bowels can trigger cramps, bloating, stomach pain, and a decrease in hunger.

Constipation is often caused by the intestines absorbing a lot of water from your digestive system, due to it being needed elsewhere. This slows the movement of faecal matter and prevents you from being able to poo. A common cause of constipation is through eating foods which you have a sensitivity to.


Diarrhoea can be very embarrassing when an attack strikes; but what is it? Diarrhoea is an increase in the frequency of excretion, usually, the stool is much looser and liquid-like.
Since it’s pretty natural to try and hold it until you’re near a toilet, it’s commonly followed by a painful stomach and bloating. You may find a fever or increased thirst is also present if it’s linked with an ongoing illness.

Diarrhoea is common among those with an undiagnosed food allergy or intolerance. The digestive system tries to remove the trigger food by flushing it out of the system as quick as possible. If you suffer from regular diarrhoea, then an allergy or intolerance test could help prevent it. Regularly consuming something that you’re allergic to for a prolonged period could cause IBS (Irritable Bowel Syndrome) and malabsorption of nutrients.


Referring to both physical and mental exertion, this is easily missed as a sign of food sensitivity. In today’s fast-paced world and busy, many can ignore feeling tired, passing it off as an unequal work/life balance. Disregarding these symptoms for too long have shown to be a primary cause of mental health issues.

Due to the body needing longer to properly process foods that it’s reacting to, it has to use more energy to aid digestion. Understanding your allergies and intolerances can help you avoid these items allowing you to digest more efficiently and have more energy.


A sudden headache can be crippling and inhibit you from getting through your normal day. There are different types of headaches though, categorised into primary and secondary. But its only secondary headaches that can be caused by intolerances and allergies.

Eating trigger foods or simply smelling the items can be enough to set off a headache, due to vapours entering the nasal canal. Unfortunately, headaches are a highly misdiagnosed intolerance symptom, due to their association with more commonly known problems, such as:

  Dehydration (see constipation)
  Panic attacks
  Tooth ache
  Or even hangover

Intolerance & sensitivity tests

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