# Is it a cold or the flu?

*The Centers for Disease Control and Prevention says the two illnesses share symptoms, so it can be difficult to tell them apart on symptoms alone, and that tests can show whether a person has flu.*

- Type: Explainer
- Section: Health
- By: Health Desk
- Published: 2026-11-12T01:24:40-05:00
- Updated: 2026-11-12T01:24:40-05:00
- URL: https://factsdesk.com/health/is-it-a-cold-or-the-flu/

Topics: [CDC](https://factsdesk.com/topic/cdc/)

## Key facts

- The CDC says flu is in general worse than the common cold, with symptoms that are typically more intense and begin more abruptly, while cold symptoms are usually milder. Source: [Centers for Disease Control and Prevention](https://www.cdc.gov/flu/about/coldflu.html). Confirmed 2026-11-12T01:24:00-05:00. Cite: https://factsdesk.com/health/is-it-a-cold-or-the-flu/#the-cdc-says-flu-is-in-general-worse-than-the-common-cold
- Flu and the common cold have similar symptoms, so it can be difficult to tell the difference between them based on symptoms alone, according to the CDC. Source: [Centers for Disease Control and Prevention](https://www.cdc.gov/flu/about/coldflu.html). Confirmed 2026-11-12T01:24:00-05:00. Cite: https://factsdesk.com/health/is-it-a-cold-or-the-flu/#flu-and-the-common-cold-have-similar-symptoms-so-it-can-be
- The CDC's comparison lists the onset of a cold as gradual and the onset of flu as abrupt, and lists fever as rare with a cold and common with flu. Source: [Centers for Disease Control and Prevention](https://www.cdc.gov/flu/signs-symptoms/index.html). Confirmed 2026-11-12T01:24:00-05:00. Cite: https://factsdesk.com/health/is-it-a-cold-or-the-flu/#the-cdc-s-comparison-lists-the-onset-of-a-cold-as-gradual
- The CDC says people with colds are more likely to have a runny or stuffy nose than people who have flu. Source: [Centers for Disease Control and Prevention](https://www.cdc.gov/flu/about/coldflu.html). Confirmed 2026-11-12T01:24:00-05:00. Cite: https://factsdesk.com/health/is-it-a-cold-or-the-flu/#the-cdc-says-people-with-colds-are-more-likely-to-have-a
- Testing is the only way to know if a person has flu, the CDC says, though a health care provider may diagnose flu based on symptoms. Source: [Centers for Disease Control and Prevention](https://www.cdc.gov/flu/testing/index.html). Confirmed 2026-11-12T01:24:00-05:00. Cite: https://factsdesk.com/health/is-it-a-cold-or-the-flu/#testing-is-the-only-way-to-know-if-a-person-has-flu-the-cdc

Flu is in general worse than the common cold, with symptoms that are typically more intense and begin more abruptly, while cold symptoms are usually milder, according to the [Centers for Disease Control and Prevention](https://www.cdc.gov/flu/about/coldflu.html). The agency says the two illnesses have similar symptoms, so it can be difficult to tell the difference between them based on symptoms alone. This page reports what the CDC states and is not personal medical advice.

## How the CDC compares the symptoms

The CDC's page on the [signs and symptoms of flu](https://www.cdc.gov/flu/signs-symptoms/index.html) carries this comparison of a cold and flu:

| Sign or symptom | Cold | Flu |
| --- | --- | --- |
| Symptom onset | Gradual | Abrupt |
| Fever | Rare | Common; lasts 3 to 4 days |
| Aches | Slight | Common; often severe |
| Chills | Uncommon | Fairly common |
| Fatigue, weakness | Sometimes | Usual |
| Sneezing | Common | Sometimes |
| Chest discomfort, cough | Mild to moderate; hacking cough | Common; can be severe |
| Stuffy nose | Common | Sometimes |
| Sore throat | Common | Sometimes |
| Headache | Rare | Common |

The agency's [Cold Versus Flu](https://www.cdc.gov/flu/about/coldflu.html) page says people with colds are more likely to have a runny or stuffy nose than people who have flu. For the full list of flu symptoms and the emergency warning signs the CDC names, see [What are the symptoms of the flu?](/health/what-are-the-symptoms-of-the-flu/)

## Different viruses cause them

The CDC [says](https://www.cdc.gov/flu/about/coldflu.html) flu and the common cold are both contagious respiratory illnesses, but they are caused by different viruses. Flu is caused by influenza viruses only. The common cold can be caused by a number of different viruses, including rhinoviruses, parainfluenza and seasonal coronaviruses.

The agency's [About Common Cold](https://www.cdc.gov/common-cold/about/index.html) page says more than 200 respiratory viruses can cause colds, and that rhinoviruses are the most frequent cause of colds in the United States. The same page says the viruses that cause COVID-19, flu and RSV can also cause cold-like symptoms but do not cause colds, and that those viruses are more likely to cause severe illness.

## What the CDC says about a cold

The CDC's [About Common Cold](https://www.cdc.gov/common-cold/about/index.html) page says colds usually last less than a week. It says the signs and symptoms of a cold usually peak within 2 to 3 days of infection and can include:

- Runny nose
- Nasal congestion
- Cough
- Sneezing
- Sore throat
- Headache
- Mild body aches
- Fever, which the page says is usually low grade in older children and adults

The same page says adults in the United States have an average of two to three colds every year, and children often have more.

## How serious each one can be

The CDC's [Cold Versus Flu](https://www.cdc.gov/flu/about/coldflu.html) page says colds generally do not result in serious health problems, such as pneumonia, bacterial infections or hospitalizations. It says flu can have serious associated complications.

For how long flu illness runs, see [How long does the flu last?](/health/how-long-does-the-flu-last/) For when flu circulates, see [When is flu season?](/health/when-is-flu-season/)

## How flu is diagnosed

The CDC [says](https://www.cdc.gov/flu/about/coldflu.html) special tests can tell if a person is sick with flu. Its page on [flu diagnosis](https://www.cdc.gov/flu/testing/index.html) says testing is the only way to know if a person has flu, though a health care provider may diagnose flu based on symptoms.

That page says a number of tests are available to detect influenza viruses in respiratory specimens. It says rapid influenza diagnostic tests can provide results within approximately 10 to 15 minutes but may not be as accurate as other flu tests.

The CDC's [About Common Cold](https://www.cdc.gov/common-cold/about/index.html) page tells people who have cold-like symptoms and suspect they have COVID-19 or flu to get tested. For how much flu is circulating now, see [Is flu and respiratory illness high in my state?](/health/is-flu-and-respiratory-illness-high-in-my-state/)

## Sources

1. [Cold Versus Flu](https://www.cdc.gov/flu/about/coldflu.html), Centers for Disease Control and Prevention, 2024-08-08 (primary source)
2. [Signs and Symptoms of Flu](https://www.cdc.gov/flu/signs-symptoms/index.html), Centers for Disease Control and Prevention, 2024-08-26 (primary source)
3. [About Common Cold](https://www.cdc.gov/common-cold/about/index.html), Centers for Disease Control and Prevention, 2026-02-19 (primary source)
4. [Diagnosis for Flu](https://www.cdc.gov/flu/testing/index.html), Centers for Disease Control and Prevention, 2026-03-10 (primary source)