Allergy Symptoms

Allergy is a condition in which the immune system responds to a substance that is, in itself, harmless. The immune system is programmed to give a physiological response to any substance entering the body (or produced within it) which it considers to be ‘foreign’. When these substances are harmful, like bacteria, toxins, viruses and cancer cells, then the immune response does a good job of protecting the body. However, when it produces an allergic response to an otherwise harmless substance, like pollen and house dust mite, the allergic person experiences various symptoms. The presence of the allergen causes the immune system to produce molecules known as Immunoglobulin E (IgE) and these, in turn, react with immune cells called mast cells, causing them to produce a chemical called histamine. It is histamine which acts on cells, producing allergy symptoms like sneezing and itching. So allergic reactions occur after you have come into contact with an allergen, however, exposure to allergens produces no immune response in a person who is not allergic.

Why allergic symptoms occur is not completely understood, but allergies do tend to run in families and there is likely a strong genetic component. A person who has a predisposition to allergic disease is said to be atopic and it is this condition of atopy which is inherited, rather than a specific allergy.

Inhalation, ingestion or skin contact can produce allergic symptoms. In the UK, the most common inhaled allergens (in order) are:

1. House dust mite
2. Grass pollen
3. Cat Dander
4. Tree pollen

Common food allergens include:

• Shellfish
• Peanuts
• Tree nuts
• Strawberries
• Cow's milk
• Eggs

Other common triggers for allergy symptoms are:

• Mould spores
• Bee and wasp venoms
• Latex
• Chemicals

Allergy symptoms can also be caused by the use of certain drugs.

The most common allergic symptoms include:

• Sneezing
• Coughing
• Skin rash
• Blocked nose
• Itching
• Watery eyes

These symptoms may have non-allergic causes, however, the doctor and patient should look for patterns in the symptoms which may suggest allergy – that is, a clear connection between exposure to a potential allergen and the appearance of symptoms. If necessary, skin prick tests or blood tests can be carried out to confirm the diagnosis of allergic disease.

Allergic symptoms can also be examined in terms of the underlying allergic condition. Rhinitis symptoms, for instance, are very different from the symptoms of asthma. However, the underlying immune response is broadly the same in all allergic conditions:

Coughing, Wheezing and difficulty breathing are key traits of asthma. To learn more about the symptoms of asthma please visit our asthma symptoms page.

Itchy eyes, coughing, sneezing, runny nose, and nasal blockage are some of the main symptoms of rhinitis. To learn more about the symptoms of rhinitis please visit our Rhinitis page.

Redness, discharge, and itching are all symptoms of eye allergy. To learn more about the symptoms of eye allergy please visit our Sore Eyes page.

Itchy skin, rashes, redness and weals on the skin are some of the symptoms of Urticaria (nettle rash).

Itchy skin is also a key hallmark of eczema. To learn more about the symptoms of eczema please visit our Eczema page.

The first step in preventing allergy symptoms is to know your allergen! However, an air purifier fitted with a HEPA filter will help remove all particulate contaminants including allergens, such as house dust mite allergen and pollen, from the air inside your home or place of work.

House dust mite: Try mite-proof mattress covers and wash bedding regularly at a high temperature. Vacuum regularly with a vacuum that is fitted with a High-Efficiency Particulate Air (HEPA) filter, damp dust and get rid of dust-accumulating clutter. Consider replacing carpet, which is a reservoir for house dust mite, with wooden flooring.

Mould spores: Ventilate the home well. At the very least open windows after bathing or showering and after cooking to get rid of steam. Tackle damp patches with a bleach solution.

Pollen: Be alert to daily pollen counts. Change your clothes, shower and wash your hair when coming in from outdoors. Wear wraparound sunglasses to stop pollen grains coming into contact with your eyes.

Pet dander: Unfortunately, often the most effective way to control allergy symptoms caused by pet dander, is to find a new home for the pet. Obviously, that is not always possible, as many pets are considered part of the family. The use of allergy-friendly cleaning products (such as PET+ Pet Shampoo), a HEPA equipped cat & dog vacuum cleaner and the right air purifier will go a long way in limiting your day to day exposure to allergens and thus control your allergy symptoms.

Allergy symptoms may pose no more than an occasional nuisance. However, people with severe allergies such as asthma do need to manage their condition carefully because an asthma attack is potentially fatal. Another allergic condition that can be very serious is anaphylaxis, which is a severe allergic reaction involving the whole body. Signs and symptoms of anaphylaxis include:

1. Raised blood pressure  

2. Swelling of the tissues (angioedema)  

3. Asthma attack 

4. Upset stomach

The onset of these allergy symptoms is usually rapid and may escalate into a life-threatening condition known as anaphylactic shock, which must be promptly treated by an adrenaline injection. This can be self-administered. For example, people with severe peanut allergies tend to carry one with them as they know they are prone to anaphylactic shock.

Urticaria, which is also known as nettle rash (the word 'urtica' is Latin for stinging nettle), is a skin condition which may have an allergic origin (though the majority of cases are not allergic). Allergens causing urticaria include:

Bee and wasp stings Foods like shellfish, fruit, nuts and dairy products Some drugs

Urticaria appears as an itchy rash consisting of small weals on the skin, having the appearance of multiple insect bites. Sometimes the weals are larger and raised, appearing red at the edge and white in the middle. The rash does not leave any scars but the skin may feel slightly numb following an attack.