Everything you want
to know about allergies

Advice and recommendations
for patients from EAACI experts

EAACI has developed this website to offer updated and reliable information on allergy to patients & families. Disclaimer

List of symptoms

The symptoms caused by allergy can be considered in fact as defence mechanisms to protect our organism from allergens. The symptoms also act like an alarm, warning us that something is wrong. But these defence mechanisms can become harmful for ourselves. Persons without allergy have other defence mechanisms that do not harm them and thus allergens go unnoticed.

 

The most frequent symptoms associated to allergic disorders are shown here in alphabetical order. You can check them by the organ involved with our Allergy Body Guide.

 

IMPORTANT TO NOTE: None of these symptoms are exclusive of allergy. Any of them can be caused by other conditions, some of them very serious. The symptoms are shown here for information, but if you suffer from them we recommend you to visit a doctor.

 

Abdominal pain

A pain in the belly, often associated to vomiting or diarrhoea, appears when the digestive system if not correctly functioning. When the pain is colicky it is due to the accelerated movement of the bowels trying to expel their contents as fast as possible. This is associated to allergic disorders such as food allergy, hereditary angioedema and anaphylaxis.

 

Chest tightness

Sensation of a pressure of the chest, like having a weight on it, that causes difficult breathing. It appears when we try to expand our chest so that the air comes in. if the airways are narrowed and the air cannot pass easily you feel that sensation. This is associated to allergic disorders such as asthma or anaphylaxis.

 

Cough

When we cough we expel air from the lungs forcefully, which helps to clear the airways from secretions, irritants, foreign particles such as allergens and microbes. This is associated to allergic disorders such as asthma, rhinitis, rhinosinusitis, hay fever and anaphylaxis.

 

Diarrhea, or diarrhoea


Discharge of loose or liquid stools, when a food has not been digested or due to an accelerated transit of the food in the bowels, to expel something that the organism does not admit. This is associated to allergic disorders such as food allergy and anaphylaxis.

 

Difficult breathing or shortness of breath, or breathlessness, or dyspnea, or dyspnoea

This feeling of difficulty to inhale or exhale air appears when we try to breathe through a narrowed airway. It is a warning signal, and if not reverted, it can lead to exhaustion of the respiratory muscles. You can have this feeling if you try to breathe through a straw. This is associated to allergic disorders such as asthma and anaphylaxis.

 

Difficult swallowing

A feeling of pain or discomfort when swallowing, or even the sensation that the food is stuck, can appear when the food passes through a constricted and rigid oesophagus, due to the infiltration of inflammatory cells. This is associated to allergic disorders such as eosinophilic esofagitis.

 

Dizziness

Dizziness is impairment in spatial perception and stability. It can appear due to a drop in blood pressure, called shock when it is extreme. This is associated to allergic disorders such as anaphylaxis.

 

Eye circles

The blood coming from the eyes and going to the heart passes through the veins in the nose. If they are congested due to inflammation of the nasal mucosa, eye circles appear. This is associated to allergic disorders such as rhinitis, hay fever, conjunctivitis and anaphylaxis.

 

Eye itching

Due to infiltration of cells in the nasal mucosa it is an alarm signal warning that something is going wrong in our eyes. This is associated to allergic disorders such as conjunctivitis and anaphylaxis.

 

Eye redness

Due to the dilation of blood vessels in the surface of the eyeballs, these appear red. This is associated to allergic disorders such as conjunctivitis and anaphylaxis.

 

Headache

Among many other causes headache can occur due to nasal congestion or to the blockage of mucus secretion in the sinuses, cavities within the bones of the head. This is associated to allergic disorders such as rhinitis, hay fever and rhinosinusitis.

 

Heartburn

This burning sensation beneath the breastbone can appear when the acid content of the stomach is moved backward to the oesophagus, due to a malfunctioning of the junction between the oesophagus and the stomach. This is associated to allergic disorders such as eosinophilic esofagitis.

 

Loss of smell

The loss of this sense is due to a malfunctioning of the nose when there is an infiltration of the nasal mucosa or an abnormal growth of tissue forming polyps. This is associated to allergic disorders such as rhinitis, hay fever and nasal polyposis.

 

Nasal blockage

The blocking of passage of the air through the nose can happen when there is an obstruction due to mucus secretion, to the inflammation of the nose, to the hypertrophy of the bones inside the nose called turbinates, or to the growth of tissue inside the nose forming polyps. This is associated to allergic disorders such as rhinitis, hay fever, nasal polyposis and anaphylaxis.

 

Nausea

This sensation of unease and discomfort in the upper stomach with an involuntary urge to vomit commonly precedes vomiting, which is a defence mechanism to get rid of a content of the stomach that has been identified as harmful by our organism. This is associated to allergic disorders such as food allergy and anaphylaxis.

 

Nose bleeding

Bleeding from the nose can happen when the nasal mucosa is infiltrated and thus congested with blood vessels and very fragile. This is associated to allergic disorders such as rhinitis, hay fever and nasal polyposis.

 

Nose itching

Due to infiltration of cells in the nasal mucosa it is an alarm signal warning that something is going wrong in our nose. This is associated to allergic disorders such as rhinitis, hay fever and anaphylaxis.

Nose mucus

Either liquid or thick, transparent or coloured, the mucus in the nose has the objective of catching and neutralizing stimuli identified as harmful. This is associated to allergic disorders such as rhinitis, hay fever and anaphylaxis.

 

Skin itching

The sensation that causes the desire or reflex to scratch appears due to the stimulation of skin receptors and may act as a signal that something is wrong. This is associated to allergic disorders such as atopic dermatitis, contact dermatitis, urticaria and anaphylaxis.

 

Skin redness, dryness, desquamation or skin peeling


They appear when the blood vessels are dilated due to harmful stimuli, when the protecting fatty layer of the skin is not repaired, and when the normal cycle of renewal of the skin is impaired. These are associated to allergic disorders such as atopic dermatitis or contact dermatitis.

 

Sneezing


This sudden loud expulsion of air from the lungs through the nose and mouth helps clearing the airways from substances identified as harmful. This is associated to allergic disorders such as rhinitis, hay fever and anaphylaxis.

 

Swelling, or edema, or oedema, or inflammation of the skin


It is due to the drip of liquid from the blood vessels to the deeper layers of the skin. This is associated to allergic disorders such as urticaria, anaphylaxis and hereditary angioedema.

 

Swollen eyelids


They appear due to the drip of liquid from the blood vessels to the skin, due to a local congestion or to a generalised reaction. This is associated to allergic disorders such as rhinitis, hay fever, conjunctivitis, anaphylaxis and hereditary angioedema.

 

Swollen face


It appears due to the drip of liquid from the blood vessels to the skin, due to a local or a generalised reaction. This is associated to allergic disorders such as urticaria, anaphylaxis and hereditary angioedema.

 

Tearing


The secretion of tears helps clearing the eyes from foreign substances; at the same time some components in the tears neutralise these substances. This is associated to allergic disorders such as conjunctivitis and anaphylaxis.

 

Vomiting


The involuntary, forceful expulsion of the contents of one's stomach through the mouth and sometimes the nose has the objective of getting rid of a content that the organism identifies as harmful. This is associated to allergic disorders such as food allergy and anaphylaxis.

 

Weals, also spelled wheals, or hives.


They are pale red, raised, itchy bumps in the skin, due to the drip of liquid from the blood vessels to the superficial layers of the skin. They are associated to allergic disorders such as urticaria and anaphylaxis.

 

Wheeze


Whezzing is a whistling sound produced during breathing, when the air passes through a narrowed or obstructed airway. It can happen in bronchospasm, when bronchi contract trying to prevent the passage of harmful stimuli, but at the same time this constriction impairs the passage of air. This is associated to allergic disorders such as asthma or anaphylaxis.