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Differences Between Allergies, Colds, and the Flu

Carola is a freelance writer who enjoys writing about health topics and current social issues.

Allergies, the common cold, and the flu have an equal impact on us—they make us physically miserable. Our bodies ache, sneeze and cough. We long for some chicken soup, a hot cup of tea, and some bed rest. Although a number of the symptoms of these three conditions are similar, the National Institutes of Health says that we need to distinguish which one is plaguing us in order to determine if it is contagious and whether intervention by a medical professional is required.

It is difficult for medical professionals to diagnosis which is which, say experts at Texas A&M University. Doctors make decisions based on supportive diagnostic data and the symptoms. Here are the main characteristics of each malady.

Common Symptoms of Colds, Flu & Allergies


Congestion – chest, head, or nasal



Mild to moderate cough

Dry cough, can be severe

Cough, wheezing, chest tightness

Mild fever

Fever over 101 degrees F


Runny nose

Runny nose

Itchy, runny nose

Mild fatigue

Fatigue, may be severe



Occasional stuffy nose or sneezing


Sore throat

Sometimes a sore throat

Sore throat from post-nasal drip

Watery nose or eyes


Watery, red, and itchy eyes

Mild body aches

Aches all over the body, may be severe







swollen tongue, lips, eyes or face




The common cold

Colds are caused by viral infections. Colds can happen at anytime, but are more prevalent during the winter months, when The only treatment is good nutrition, plenty of fluids, and lots of rest. Certain medications such as over-the-counter decongestants, cough remedies, and nasal sprays can ease the symptoms, but antibiotics are not effective against colds. The condition will go away within a week and does not require medical intervention. Sometimes a cough can linger for up to a month.

Symptoms are severe and continue past a week, the patient may have a more serious chronic illness such as asthma, allergies, or other problems. Colds usually do not last more than two weeks.


The flu, also called influenza, is also a viral inflection that can be prevented by a yearly vaccine. The condition has similar symptoms, but some distinct differences. The patient should get medical treatment fast.

Anti-viral medications can be prescribed within 48 hours of the onset of symptoms to reduce their intensity and the risk of complications. Colds and the flu can both lead to conditions such as pneumonia, bronchitis, or sinusitis but are more likely to develop with the flu than with colds. Treating the symptoms and being well rested can reduce the risk of complications.

Differences Between Colds And The Flu

The symptoms of colds run their course in predictable ways, while the flu can attack suddenly. For example, sufferers will feel fine in the morning, and then be miserable with a fever and body aches in the afternoon. Both cold and flu suffers have aches and pains, but these conditions differ in intensity. Aches during a cold are generally mild and caused by congestion. Muscle pain during influenza can be present deep in large muscles such as the back and legs.

Cold and flu viruses are contagious, so it is best to stay home to avoid spreading the contagion to others. The viruses can be spread when infected people cough or sneeze, or through physical contact such as shaking hands. With the flu, it is best to take a day’s dosage of prescribed medication or make sure you have been free of fever of 24 hours.

Seasonal and Food Allergies

Pollen blowing in the air can trigger the body’s immune system, causing itchy or runny noses or eyes. The body’s overactive defence systems mistake harmless elements such as pollen or dust as germs and launch an attack against them.

Seasonal allergies are easier to diagnose because the symptoms only exist when allergens are present and lack some characteristics of colds and flu. Severe allergic reactions can cause nausea and diarrhea. The most severe reaction, known as anaphylaxis, can be life-threatening and requires immediate treatment.

Differences Between Allergies, and Colds and Flu

Unlike colds or flu, there are tests that can identify the things that trigger allergic reactions such as certain foods, insect stings, animal dander, dust mites, molds, pollen, and some medicines. According to the American College of Allergy, Asthma & Immunology, there are skin and blood tests available that are done by qualified allergy specialists. Allergy skin tests involve pricking a drop of suspected allergen on the skin. This may trigger symptoms such as swelling and itchiness at the site if allergies are present.

Blood tests may cause bleeding or pain at the needle mark. Some people faint during the blood test. The results of both types of tests usually appear within 20 minutes and symptoms usually disappear within one or two days. Any signs of swelling or redness within a few hours of a test should be reported to the medical professional.

Allergies get worse in the spring and summer while respiratory illnesses are more prevalent in the fall. Influenza usually occurs from late fall, then through the winter, and early spring.

Treatment Similarities and Differences

According to the Centers for Disease Control and Prevention, it can be difficult or even impossible for medical professionals to identify whether a patient has a cold or flu based on symptoms alone. Other factors such as the duration of the condition must be considered.

Colds, flu, and allergies can be treated with over-the-counter medications such as decongestants, and antihistamines. Hydration, and lots of rest help cold and flu sufferers. Nasal irrigation systems that are used properly with previously boiled or filtered water can help to prevent sinus infections.

Influenza may require prescription medication that should be taken as indicated. A pharmacist or health care provider can provide information that will prevent double-dosing on medications.

If allergy symptoms are severe, a medical professional may recommend the use of an epinephrine autoinjector, a device that injects a dose of epinephrine (adrenaline). The medication is injected into the thigh muscle to treat a severe allergic reaction known as anaphylaxis.

Signs That Medical Intervention is Needed

A persistent fever, difficulty breathing, and/or difficulty keeping food down may be signs of rare complications, such as pneumonia. These symptoms should be treated by a medical professional.

This content is accurate and true to the best of the author’s knowledge and does not substitute for diagnosis, prognosis, treatment, prescription, and/or dietary advice from a licensed health professional. Drugs, supplements, and natural remedies may have dangerous side effects. If pregnant or nursing, consult with a qualified provider on an individual basis. Seek immediate help if you are experiencing a medical emergency.


Dora Weithers from The Caribbean on December 01, 2016:

Thanks for the explanations and the information you list showing difference between allergies, colds and the flu. It helps us identify and treat the symptoms effectively.