Common Allergy and Intolerance Symptoms | TMI Testing

Common Allergy and Intolerance Symptoms

Allergies and intolerances can cause a range of different symptoms which can make them difficult to define in each person. Additionally, a food type that may cause a reaction in one person, may create a different reaction in another. Items like dairy, gluten, nuts and pet hair are common issues, but can cause a range of reactions. Here is the list of the most common reactions, and the symptoms they can portray.


Bloating is a common symptom of intolerances and is defined as the swelling or distension in the abdomen and whilst it means a visible distension for some, others have the sensation without any visible physical change. Due to bloating being contained to the digestive system, it is often linked with excess wind (eructation and flatulence), discomfort and stomach swelling.

Bloating can come from numerous different imbalances within the body, the main one being food allergy or intolerance.

Symptoms can also occur as a side effect from dehydration, anxiety, stress and pregnancy.

Other causes are:


  Lacking nutrients (or struggling to absorb them)

  Bacteria imbalance

  Nerve damage

  Abnormal intestinal contractions

Bloating no fade - Common Allergy and Intolerance Symptoms
Bloating Pictures - Common Allergy and Intolerance Symptoms


The opposite of diarrhoea, constipation is where you find it difficult to defecate, or your stools can be painful to pass. Due to the increased excrement in your bowels, it 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 as it’s needed elsewhere. This slows the movement of faecal matter and stops you from being able to poo. A common cause of constipation is through the consumption of items which you have a sensitivity to.

Constipation 4 2 - Common Allergy and Intolerance Symptoms
Constipation Children - Common Allergy and Intolerance Symptoms


Regular sufferers of diarrhoea know how embarrassing it can be when an attack strikes; but what actually is it? Diarrhoea is an increased occurrence of excretion, usually with a much looser, liquid-like stool. As it’s human nature to try to hold the poo until you’re near a toilet, it can be followed by a painful stomach and bloating. If linked with an ongoing illness, you may find a fever or increased thirst is also present.

Diarrhoea is a common symptom of an undiagnosed food allergy or intolerance. The digestive system is trying to remove the offending item by flushing it out of the system. If you suffer from regular diarrhoea, then you should seek an allergy or intolerance test. Consuming an item that you are allergic to for an increased amount of time could cause IBS (Irritable Bowel Syndrome) and malabsorption of nutrients.

Diarrhoea - Common Allergy and Intolerance Symptoms


This is either physical, or mental exertion and is easily missed as a food sensitivity symptom. Due to living busy lives, people can ignore feeling tired and pass it off as unequal work/life balance. Disregarding these symptoms in the long-term have shown to be a primary cause of mental health issues.

Due to the body needing to properly process foods which it is having a reaction to, it has to use your energy to aid digestion. Understanding your allergies and intolerances can help you to avoid these items allowing you to sleep better and have more energy.

fatigue - Common Allergy and Intolerance Symptoms
Fatigue Infographic - Common Allergy and Intolerance Symptoms


A sudden headache can be incapacitating when trying to live your normal life. There are two types of headaches: primary and secondary however it’s only secondary headaches which are caused by food or non-food intolerances and allergies. Headaches can be caused by consuming foods or smelling items which, you should be avoiding. Vapours can enter the nasal canal and directly cause your headache.

Unfortunately, headaches are one of the most misdiagnosed intolerance symptoms, due to their confusion with:

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

Headache Infographic 1 1 - Common Allergy and Intolerance Symptoms
Headaches 1 - Common Allergy and Intolerance Symptoms