What Causes a Cold?

Colds come from one of more than 200 viruses. They primarily spread through droplets that enter the air when someone with a cold sneezes, coughs or talks. You can catch a cold by breathing in these droplets or by touching surfaces contaminated with them and then touching your eyes, nose or mouth.

When you experience symptoms of illness, consider whether you’ve been around anyone who was recently ill or if someone with a cold recently touched any items you use, such as your remote control or doorknob. If so, the chances of sneezing, coughing and other symptoms being from a cold are greater.  

What Causes Allergies?

Allergies happen due to immune system activities. When functioning properly, the immune system protects you from illnesses by releasing various chemicals in response to germs. If you have allergies, your immune system mistakes a harmless substance for a germ. It then triggers an inflammatory response to fight the perceived threat.

Allergens are substances that trigger allergies. Some of the most common ones include:

• Dust
• Mold
• Pet dander
• Pollen

Recent exposure to common allergens can indicate your symptoms are due to allergies. For example, you may have allergies if you begin to sneeze after visiting someone who owns a dog or taking a long walk outside.

Differences Between Colds and Allergies

Familiarizing yourself with the following key differences between a cold and allergies can help you distinguish between them.

Specific Symptoms

Colds and allergies do share a few common symptoms, including sneezing, runny nose and nasal congestion. However, some symptoms are more likely to occur with one rather than the other. These include:

• Cough. Colds usually cause coughs. Allergies may lead to coughing, but it’s less common.
• Eye symptoms. Allergies often trigger eye redness, watering and itching, while colds rarely affect the eyes.
• Fever. Allergies usually don’t cause a fever, but a cold can.
• Sore throat. While it’s possible for drainage from allergies to cause scratchiness, a sore throat is more often a symptom of a cold.

Mucus colors can also indicate the cause of your symptoms. With allergies, mucus is usually clear. If you have a cold, you’re more likely to see green or yellow mucus.

Symptom Trends

General characteristics of your symptoms can also help you tell colds and allergies apart. Cold symptoms tend to come on gradually. They begin as mild and grow more severe over a couple of days. Then they wane and resolve in around 1 to 2 weeks.

Allergy symptoms usually start suddenly, and they may be moderate to severe right away. Your symptoms may persist until you no longer have contact with the allergen. For example, tree pollen season in Colorado generally begins in the spring and continues into early summer. If you’re allergic to tree pollen, you may have continual symptoms or symptoms that come and go during this entire period.

What Provides Relief?

Monitoring what relieves your symptoms can also be beneficial when trying to determine whether you have a cold or allergies. Generally, oral antihistamines are the primary treatment for managing allergy symptoms. These over-the-counter drugs usually don't have much of an effect on colds. Before trying one of these medications, be sure to consult your health care provider.

Preventing Colds and Allergies

Although you can’t completely prevent colds or allergies, you can reduce your likelihood of experiencing both. To minimize your risk of catching a cold:

• Wash your hands frequently with soap and water for at least 20 seconds.
• Use hand sanitizer that's at least 60% alcohol when you can’t wash your hands.
• Avoid sharing silverware and drinking glasses.
• Disinfect high-touch surfaces like phones, countertops, doorknobs and light switches frequently.
• Stay away from people who are sick when possible; when not, wear a mask.

To help prevent allergy symptoms:

• Wash your hands after petting animals and when you come in from outside.
• Don’t allow pets in your bedroom.
• Vacuum regularly.
• Regularly wipe down surfaces with soapy water to remove dust.
• Monitor local pollen reports and stay indoors as much as possible when counts are high.
• Close your windows when pollen levels are up.

Colds vs. Allergies: Which Do You Have?

Knowing about the differences between colds and allergies can give you a good idea of what’s causing your symptoms. However, the only way to know for sure is to see your health care provider. They can conduct an examination and run tests to diagnose allergies and colds. If it turns out you have allergies, your health care provider can develop a treatment plan to help you stay active and healthy going forward.