What are the symptoms of allergies?

What are the symptoms of allergies?

What are the symptoms of allergies?

Allergy symptoms

The symptoms of allergies are dependent on the substance that is involved, as the substance dictates what area of the body is affected and how this will manifest. For example, food is eaten, therefore the gut is affected.

Affected areas may include the airways, nasal passages and sinuses or the digestive system. The level of allergic reaction experienced will range from minor to severe. Severe cases of allergies can sometimes trigger a reaction that is known to be life-threatening, called anaphylaxis.

Allergy symptoms are as follows:

  • Hay Fever (allergic rhinitis), which can cause:
    • An itchy nose, itchy eyes or the roof of one’s mouth to itch
    • Sneezing
    • A blocked or runny nose
    • Red, watery or swollen eyes - this is also known as conjunctivitis (and in the case of allergies, allergic conjunctivitis)
  • Food allergies may cause:
    • The mouth to tingle
    • Swelling of the lips, tongue, throat and/or face
    • Hives (skin rash)
    • Anaphylaxis (a severe reaction to food where the patient’s throat can swell to a point where they cannot breathe)
  • Insect sting allergies may cause:
    • Oedema at the site of the sting, this is a large area of swelling which is the result of excess fluid in the tissues
    • Hives (skin rash) or itching all over the patient’s body
    • Coughing, tightness of the chest, shortness of breath or wheezing
    • Anaphylaxis
  • Drug allergies may cause:
    • Hives (skin rash)
    • The skin to itch
    • The face to swell
    • Wheezing
    • Anaphylaxis
  • Eczema, also known as atopic dermatitis, which is an allergic reaction of the skin, may result in the skin:
    • Peeling or flaking
    • Itching
    • Reddening
  • Allergic contact dermatitis occurs when the skin comes into contact with trigger substances such as latex, nickel (in jewellery), chemicals used to treat leather (especially on some watch straps), plants like poison ivy or poison oak, fragrances used in soaps, hair products and cosmetics. This can cause:
    • A raised, red rash
    • Blistering of the skin
    • A burning sensation or pain at the site of the rash
    • Itching of the skin


Pronounced an-a-fi-lak-sis.

As previously mentioned, there are some types of allergic reactions and allergies, which predominantly tend to include insect bites and foods, that can have a potentially life-threatening reaction if left untreated. This reaction is known as anaphylaxis and can result in the patient going into anaphylactic shock.

Some of the signs to take note of in this type of emergency situation are:

  • A skin rash
  • Vomiting and nausea
  • Difficulty breathing
  • A weak and rapid pulse
  • A drop in the blood pressure of the patient
  • Fainting

The symptoms of anaphylaxis are further explained in the following section:

Symptoms of anaphylaxis

Anaphylaxis refers to the rapid onset of a severe allergic reaction. This means that the symptoms appear soon after the patient has come into contact with the allergen. Anaphylaxis needs to be treated as an emergency situation as it is life-threatening.

There are a number of symptoms characteristic of this type of allergic reaction which appear between a few minutes or even hours after the allergen exposure.

If the exposure enters the body intravenously, for example, penicillin being injected into the body, the onset of symptoms will take place between five and 30 minutes after exposure. A food allergy will normally take longer. 

A study was done at the University of Manitoba in Canada that reported the most commonly affected anaphylaxis areas, listed in order, to be the:

  • Skin
  • Respiratory system
  • Digestive system
  • Cardiovascular system (heart)
  • Central nervous system

In the majority of the cases, two of the above areas will be affected simultaneously.

Skin symptoms of anaphylaxis

Flushing, itchiness and hives in various areas on the body are typical symptoms of anaphylaxis evident on the skin. Angioedema or oedema may also occur. This is when the tissue under the skin swells (it is typically drug-induced). It is also not uncommon to experience a burning sensation. In some cases, the patient’s throat and tongue may also swell.

If the skin rash develops into a bluish colour, this may be indicative of hypoxia, which is a lack of oxygen due to the patient’s throat closing.

Some patients also experience a stuffed or a runny nose. The covering of the front of the patient’s eye, as well as the eyelid, may also swell.

Respiratory symptoms of anaphylaxis

  • Wheezing as a result of the spasms of the bronchial muscles
  • Difficulty in breathing
  • A high-pitched wheezing noise when breathing, known as stridor, which is caused by the upper airways being obstructed due to swelling
  • Hoarseness
  • Coughing
  • Difficulty and pain when swallowing, this is known as odynophagia

Cardiovascular symptoms of anaphylaxis

The muscles in the artery walls can suddenly tighten temporarily as a result of the cells releasing histamine. This is known as a coronary artery spasm. This can sometimes lead to a heart attack, abnormal heart rhythm and even cardiac arrest (when the heart stops beating).

If the patient’s blood pressure drops, this can cause an accelerated heart rate, resulting in the patient feeling dizzy and lightheaded, which can lead to a loss of consciousnesses.

Gastrointestinal symptoms of anaphylaxis

  • Diarrhoea
  • Vomiting
  • Pelvic pain
  • Loss of bladder control
  • Abdominal cramps

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