Is It a Cold or Allergies? 5 Telltale Signs

When you’re sniffling, sneezing, and reaching for the tissues, it can be hard to tell whether you’re dealing with a cold or seasonal allergies. While both can make you feel run-down, the causes (and the best treatments) are very different. 

The team at Internal Medicine of Greater New Haven shares five key ways to spot the difference so you can get the proper care and start feeling better faster.

1. Take a look at how and when your symptoms start

A cold usually begins suddenly. One day you feel fine, and the next, you’re congested and achy. Colds are caused by viruses, which spread through coughing, sneezing, and touching contaminated surfaces.

You might also suspect that you have a cold if your symptoms start shortly after spending time with someone who was sick. The incubation period for a cold is one to three days. This means that if your symptoms appear suddenly, one to three days after you’ve been exposed to the virus, you might be dealing with a cold.

Allergies, on the other hand, tend to develop gradually after exposure to triggers such as pollen, dust, or pet dander. Symptoms often flare up at the same time each year or in specific environments.

2. The length of your symptoms

A cold typically runs its course in about 7–10 days, while allergies can linger for weeks or even months, as long as you’re exposed to the allergen. This is especially true if your allergens are present indoors, such as cat dander or dust mites.

If your symptoms never seem to go away, it’s more likely that you have allergies than a lingering cold.

3. The color of your mucus

It may not be the most glamorous detail, but the color of your mucus can actually reveal a lot.

When you have a cold, your mucus often starts clear and becomes yellow or green as your body fights off the virus. That’s because your immune system releases white blood cells to attack the infection, and as those cells break down, they release enzymes that tint the mucus yellow. This is a sign your body is hard at work healing.

With allergies, however, mucus usually remains clear and watery, as your immune system is reacting to something harmless (such as pollen or pet dander), not fighting an actual infection.

4. Whether you have a fever and body aches

If you have a fever, fatigue, or a sore throat, it’s probably a cold. (Sometimes cold symptoms can overlap with flu symptoms or COVID-19 symptoms, but a quick flu/COVID-19 test can rule that out.) 

Allergies don’t cause fever, chills, or body aches, though severe congestion can make you feel drained.

Instead of a fever, allergies are more likely to cause itchy, watery eyes. In fact, 40% of the population experiences itchy eyes related to allergies, but many people don’t reach out for help, not realizing the source.

5. What makes your symptoms better (or worse)

Pay attention to when your symptoms flare up.

Colds often worsen over the first few days and improve with rest, fluids, and time. You may find that your congestion eases with a steamy shower, and your sore throat dissipates with a hot cup of tea.

Allergies persist or worsen when you’re exposed to triggers. You may notice symptoms indoors with pets or outdoors during high pollen counts, and find relief when you avoid these triggers or take an antihistamine.

When to see a doctor

If you’ve had symptoms for more than 10 days, can’t tell whether it’s a cold or allergies, or have trouble breathing, it’s time to see your doctor. 

Your provider at Internal Medicine of Greater New Haven can perform a physical exam, review your symptoms, and recommend testing to confirm the source of your symptoms. Once we’ve identified the culprit, we can help you get started with treatment, whether that involves allergy management, decongestants, or other care.

Feeling congested? Come visit us

You don’t have to guess what’s behind your congestion. Whether it’s seasonal allergies or a stubborn cold, the team at Internal Medicine of Greater New Haven can help you find relief.

Call 203-848-1803 or book an appointment online to get started at any of our nine Connecticut locations.