What are the symptoms of allergies?

What are the symptoms of allergies?

The symptoms of allergies depend on the substance involved and the manner in which one is exposed to it, as this dictates the area of the body affected and how symptoms will manifest.

 Affected areas may include the airways, nasal passages and sinuses or the digestive system. The level of allergic reaction experienced can 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 build-up 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.

There are some types of allergies which result in severe allergic reactions. These predominantly include insect bites and certain foods, which can lead to a potentially life-threatening situation if left untreated. This is known as anaphylaxis and can result in the affected person 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 blood pressure
  • 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 affected person has come into contact with an allergen.

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

If the exposure occurs intravenously, for example, penicillin being injected into the body, the onset of symptoms will take place within five to 30 minutes. A food allergy will normally take longer to manifest symptoms. 

A study conducted at the University of Manitoba in Canada detailed the most commonly affected anaphylaxis areas, listed in order of prevalence, as:

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

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

Skin symptoms of anaphylaxis

Flushing, itchiness and hives in various areas of the body are typical symptoms of anaphylaxis evident on the skin. Some patients also experience a stuffy or a runny nose.  Angioedema or oedema may also occur. This is when the tissue under the skin swells and is typically drug-induced. The covering of the front of the patient’s eye, as well as the eyelid, may also swell. It is also not uncommon to experience a burning sensation and in some cases, the patient’s throat and tongue may also swell.

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

Respiratory symptoms of anaphylaxis

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

If the affected person’s blood pressure drops, this can cause an accelerated heart rate. The patient may feel dizzy and lightheaded and may result in a loss of consciousnesses.

Gastrointestinal symptoms of anaphylaxis

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

How to prevent allergy symptoms

There is no specific way to prevent allergies, but there are a number of ways to stop the symptoms from occurring. These include the following:

  • Avoid triggers – This is specifically vital in the case of food allergies and these can be avoided by simply steering clear of trigger foods and examining food labels to check ingredients before consuming specific products. Airborne allergies such as pollen may be more difficult to avoid, however, if a person is aware of the periods when there is increased pollen in the air, they can stay indoors as far as possible to minimise the effects.
  • Keep an allergy diary – Identify and record certain triggers and inform the treating doctor of these as this will aid him/her in administering the most effective treatment.
  • Wear a medical band or bracelet – If a severe allergic reaction to a certain allergen such as penicillin has been experienced in the past, these bracelets can be very helpful. A bracelet may even save one’s life as they help doctors in emergency situations know what the patient is allergic to and can or can’t have.
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