What's the Difference Between Allergies and Colds?

It can be easy to mistake a cold for allergies, and vice versa. Cough, runny nose, stuffiness, for example, are common with both conditions. But while they're similar in many ways, colds and allergies are quite different. Aside from having different causes, subtle nuances in symptoms and how they present can help distinguish one from the other.

What Are Allergies?

Allergies generally occur when your immune system mistakes harmless allergens, such as dust or pollen, for germs and attacks them. When this happens, your body releases histamines and other chemicals into your bloodstream. It's the release of these chemicals that causes allergy symptoms.

One of the most common forms of allergy is seasonal allergic rhinitis (also called hay fever). It often comes along with allergic conjunctivitis, which causes eye-related symptoms.

If you have asthma, it may be triggered by seasonal allergies.

What Is a Cold?

A cold is a viral infection of the upper respiratory tract (nose, throat, and sinuses). Hundreds of viruses can cause a cold, but the most common cause of adult colds are rhinoviruses. Other viruses that cause colds include strains of coronavirus, adenovirus, and respiratory syncytial virus (RSV).

Colds are often spread through droplets in the air when a sick person coughs or sneezes. You can also catch a cold if you touch your eyes, nose, or mouth after handling something (like a doorknob) with cold viruses on it.

The virus infects the cells of the respiratory tract, multiplies, and sets off an inflammatory response that produces the cold symptoms.

After you've been exposed to a cold-causing virus, it typically takes one to three days for you to develop symptoms. These vary from person to person, but tend to be fairly similar. And although most colds go away in about a week, some symptoms (like a runny nose or cough) can take up to two weeks to clear completely.

You usually develop immunity to the specific virus that caused the cold, but with so many different viruses, you are still at risk from those you haven't caught previously. As a result, adults catch two to three colds per year, and children catch even more.

Symptoms

The onslaught of symptoms you experience from a cold or allergies is the result of your immune system fighting off potentially harmful substances (or, in the case of allergies, what the body mistakes as harmful). The cocktail of immune system chemicals your body releases to fight off the invader can cause nasal inflammation (leading to feelings of congestion) and increased mucus production (causing a runny nose and sneezing).

The most common symptoms of allergies (namely, hay fever) and colds have tremendous overlap. They include:

Given this, it can be difficult to tell the difference between the two when symptoms first strike. Thankfully, most of the time, there are a few telltale signs that can help set them apart.

Allergies
  • Itchy eyes, nose, or throat

  • Dry cough

  • Frequent sneezing

  • Runny nose with clear mucus

  • Symptoms all occur at same time

  • Can persistent for months

Colds
  • Fever

  • Cough may be productive

  • Runny nose with yellow or green mucus

  • Symptoms progress one at a time

  • Typically only lasts three to 10 days

Diagnosis

If you consult your healthcare provider, the first step in diagnosis is to take a report of your symptoms, including details on how long they have lasted/when they occur, and your medical history. Your healthcare provider may do a physical examination, checking your vital signs, evaluating your breathing and lung function, and checking your ears, eyes, nose, throat, chest, and skin.

If influenza is suspected, you may get a flu test. If you have a sore throat, you may get a strep test to rule out strep throat (which can be treated with antibiotics). There are no specific tests for colds, so those are mostly diagnosed based on your history and examination.

If observations point towards allergies, your healthcare provider may recommend allergy testing. The aim of allergy testing is to identify which allergens trigger your allergic reaction. For allergies with respiratory symptoms, these are usually skin-prick tests or blood tests.

Of course, it's important to remember that you may very well be dealing with a cold and allergies at the same time.

How to Treat Allergies

Allergy treatment aims to mitigate your response to the allergen and reduce your symptoms. The best allergy "treatment" is to avoid what causes your allergies in the first place. However, this is not always possible. In those instances, there are two types of allergy treatments that can help ease your symptoms: medications and immunotherapy.

Medications

Allergy treatment often includes medications like antihistamines and decongestants to control symptoms.

Common allergy medications include:

An allergist can help you determine which medicines are best for you.

Immunotherapy

Allergy immunotherapy can be a good option if you have severe allergies that you are unable to control. Your doctor may prescribe allergy tablets (a form of sublingual immunotherapy, or SLIT) if you're allergic to ragweed, grass pollen, or dust mites. Over time, this treatment increase your tolerance to pollen and reduce your symptoms.

If this doesn't work, your doctor may recommend allergy shots (also referred to as immunotherapy injections). Allergy shots involve regular injections that contain tiny amounts of the allergen. They reduce your immune system's overreaction to the allergen and, therefore, reduce symptoms.

How to Treat a Cold

Treatment for a cold is aimed at easing your symptoms as your body, over time, naturally gets rid of the cold virus. Self-care includes getting enough liquids to prevent dehydration, rest, and using a humidifier.

Although over-the-counter medications cannot make your cold go away, they can relieve your symptoms and help you feel better while it runs its course.

  • To lower fever and provide pain relief, you can use medications like Tylenol (acetaminophen) and Advil (ibuprofen).
  • Antihistamines, though more commonly associated with allergy treatment, can help relieve a runny nose and watery eyes related to a cold.
  • Decongestants can ease sinus congestion and a stuffy nose.
  • Expectorants thin mucus so you can clear your respiratory passages easier.

Multi-symptom cold formulas combine two or more of these medications.

A Word From Verywell

While some allergy and cold symptoms are similar, these are two very different health conditions. Knowing the differences between the two can help you decide how to treat your symptoms when they start and know whether or not you need to seek medical attention.

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