How to Distinguish Allergies from Other Common Conditions

The way the body reacts to illness, infection and some common conditions can occasionally share characteristics with allergic reactions and food allergies. Treatment varies significantly from one condition to another, so identifying the differences will enable you to choose the best course of action. Below, we’ve outlined some of the conditions that can be mistaken for an allergic reaction (or vice versa) and highlighted symptoms specific to each.

Allergic reactions

An allergic reaction is an immune system response triggered by exposure to an allergen such as pollen, mould, or a food protein¹ whereas common medical complaints that may resemble an allergy can be triggered by genetics (e.g. eczema)² or a virus (e.g. flu)³. But at times it can be challenging to identify whether what you’re experiencing is a virus or allergies.

If you tend to develop symptoms at the same time every year, it’s possible you have seasonal allergies such as hay fever or allergic rhinitis, which is more common during the warmer months.¹² One of the key differences is that these symptoms are likely to last for several weeks or months, unlike a cold or flu, which will usually disappear inside one or two weeks.⁴

Symptoms of an allergic reaction usually develop within a few seconds or minutes of exposure to a particular allergen.⁵ So if you’re experiencing symptoms shortly after eating or drinking a particular food, interacting with an animal or being exposed to mould or pollen, you’re most likely experiencing an allergic reaction.

Is it a virus or an allergy?

Cold & Flu

The common cold and flu are both infections of the upper respiratory system, which affect the nose, mouth, throat, and lungs. Both infections are caused by viruses. There are over 200 viruses that can cause a cold; however, flu is caused by the influenza virus.³ Due to the similarity of certain symptoms, people with a common cold or flu may question whether it’s a virus or allergies. Below, we have listed the symptoms to help your diagnosis.

Cold and flu symptoms include:^3,4,12

• Blocked or runny nose
• Sore throat
• Headaches
• Muscle aches
• High temperature
• Loss of taste or smell
• Fever
• Dry Cough
• Muscle aches
• Tiredness
• Diarrhoea or stomach pain
• Loss of appetite

Allergic rhinitis

Allergic rhinitis is inflammation of the inside of the nose caused by allergens such as pollen, dust, mould, or flakes of skin from certain animals. It affects 10-15% of children and 26% of adults in the UK. If symptoms are left untreated it can affect the sinuses, voice-box, throat, and lower airways, as well as the eyes and middle ear.⁶

Allergic rhinitis symptoms include:⁶

• Sneezing
• Itchy nose/itchy palate/itchy throat
• Blocked nose/stuffy nose/nasal congestion
• Runny nose (usually with clear fluid)/nasal discharge
• Red/itchy/watery eyes (that can become very sore or infected with frequent rubbing)
• Postnasal drip (the sensation of mucus running down the back of the throat)
• Cough
• Wheezing/asthma symptoms/tight chest/breathlessness
• Sinus inflammation/pain
• Feeling of an itch in ear/ear blockage
• Nose bleeds – this may be due to the lining of the nose being itchy and is often rubbed or scratched

Dust mite allergies

Dust mites are tiny creatures that live off human skin scales that have been partially digested by moulds. They thrive in a humid environment. Dust mites are commonly found in bedding, carpets, soft furnishings, and clothing.⁷

Dust mite allergy symptoms include:⁸

• Sneezing
• Runny nose
• Itchy, red, or watery eyes
• Nasal congestion
• Itchy nose, roof of mouth or throat
• Postnasal drip
• Cough
• Facial pressure and pain
• Swollen, blue-coloured skin under your eyes
• In a child, frequent upward rubbing of the nose

Food allergies

Food allergies occur when the immune system mistakenly treats proteins in food as a threat, releasing chemicals which trigger the symptoms of an allergic reaction.¹

Symptoms include:⁹

• Tingling or itching in the mouth
• A raised, itchy red rash.
• Skin turning red and itchy, but without a raised rash
• Swelling of the face, mouth, throat, or other areas of the body
• Difficulty swallowing
• Wheezing or shortness of breath
• Feeling dizzy or lightheaded
• Nausea or vomiting
• Abdominal pain or diarrhoea
• Hay fever symptoms, such as sneezing or itchy eyes

There are a variety of treatments that can help control symptoms, such as antihistamines and adrenaline.¹⁰

Identifying food allergies

As a parent it’s very important to be aware of food that could potentially trigger an allergic reaction in children and what to look out for. The foods that most commonly cause allergic reactions are:¹

• Milk
• Eggs
• Peanuts
• Tree nuts
• Fish
• Shellfish
• Some fruit and vegetables

Most children with a food allergy will have experienced eczema during infancy. The worse the child’s eczema and the earlier it started, the more likely they are to have a food allergy. Most food allergies affect children under the age of 3. Children who are allergic to milk, soy, eggs, and wheat in early life are most likely to grow out of it by the time they start school.¹ Check out our allergy tips for parents for further guidance.

Allergy testing

There are several methods of allergy testing.¹¹ We have listed the various methods below.

Skin prick testing

Skin prick testing is one of the most common allergy tests. It involves putting a drop of a potential allergen onto your forearm. The skin under the drop is then gently pricked. If you are allergic, an itchy, red bump will appear within 15 minutes.¹¹

Blood test

A sample of blood is removed and analysed for specific antibodies produced by your immune system in response to an allergen.¹¹

Patch test

Patch tests can be used to identify skin allergies such as contact dermatitis. A small amount of the suspected allergen is added to a special metal disc, which is then taped to your skin for 48 hours and monitored for an allergic reaction.¹¹

Elimination diet

If you have a suspected food allergy, you may be advised to avoid eating a particular food to see if your symptoms improve. After a few weeks, you need to re-introduce the food into your diet to see if you have an allergic reaction.¹¹