How can I tell the flu from a cold?

The flu usually starts suddenly with fever, body aches and strong fatigue. Colds tend to come on gradually and are milder. A test can confirm the flu.

How long does a sinus infection last?

Many improve within about 10 days. Symptoms that last longer, or that get better and then worse again, should be checked.

Do I need antibiotics for a sinus infection?

Not always. Most are caused by viruses and clear on their own. A clinician decides whether antibiotics are appropriate.

Can I go to work with a cold or the flu?

It is best to stay home while you have a fever and until you feel well enough to function. Follow guidance from your clinician and employer.

When should I seek emergency care for flu symptoms?

Call 911 for trouble breathing, chest pain, confusion, blue lips or face, or severe symptoms that do not improve.

Cold, Flu, or Something Else?By Kel Healthcare TeamOctober 28, 2026Updated October 28, 2026

Flu, Cold, or Sinus Infection? How to Tell the Difference

Stuffy nose and aching all over? Compare flu, cold and sinus infection symptoms, how long each usually lasts, and the signs that mean it is time to see a clinician.

Cold & Flu Sinus Infection Acute Care Same-Day Care

Medically reviewed by Dr. Karl E. Latortue, MD6 min read

Illustration of a person with a tissue and thermometer next to a tissue box and tea cup

Introduction

Stuffy nose, sore throat, headache, tired all over. Is it a cold, the flu or a sinus infection? The symptoms overlap, which is why so many people guess wrong and either rush in too early or wait too long.

This guide compares the three conditions, explains how long each usually lasts and lists the signs that mean it is time to get care. It builds on our guide to cold, flu or something else, and when to seek acute care.

Side-by-Side Comparison

	Cold	Flu	Sinus infection
Onset	Gradual over a day or two	Often sudden	Often follows a cold or allergies
Fever	Uncommon or low	Common, sometimes high	Sometimes low-grade
Body aches and fatigue	Mild	Often significant	Mild to moderate
Nasal symptoms	Runny or stuffy nose, sneezing	Sometimes	Congestion, thick discharge, facial pressure
Cough and sore throat	Common	Dry cough common	Cough and postnasal drip
Typical course	About a week	Several days to two weeks, fatigue can linger	Often improves in about 10 days; longer or worsening needs a check

Only a clinician can tell for sure, and a test can confirm the flu. Use this table to decide how quickly to seek care.

Clues Pointing to the Flu

Sudden fever, chills and aching muscles
Strong fatigue that makes you want to stay in bed
Dry cough and headache
Others around you with flu, or it is flu season

Antiviral medicines work best when started early, so call promptly if you suspect flu, especially if you are older, pregnant or have a chronic condition. See the CDC's flu information.

Clues Pointing to a Sinus Infection

Facial pain or pressure around the cheeks, forehead or eyes
Thick yellow or green nasal discharge with congestion
Symptoms that last more than about 10 days without improving
Symptoms that improve, then get worse again
Reduced sense of smell and tooth or ear pressure

Most sinus infections are viral and clear on their own, so antibiotics are not always needed. A clinician can decide whether yours is likely to benefit.

A Sore Throat That Might Be Strep

A sore throat without cough or runny nose, especially with fever and swollen glands, can be strep, which needs testing. The CDC has a helpful page on group A strep. Our guide on flu, strep and sinus infections in Brooklyn explains when to seek same-day care.

What You Can Do at Home

Rest and drink plenty of fluids.
Use saline rinses or a humidifier for congestion.
Ask a pharmacist or clinician which over-the-counter medicines are safe with your other medicines and conditions.
Stay home while you have a fever, and cover coughs and wash hands.
Monitor symptoms and seek care if they worsen or last longer than expected.

For more tips, see our post on recovering from the flu faster.

When to Get Care

Fever that lasts more than a few days or keeps returning
Symptoms that improve and then suddenly worsen
Sinus symptoms lasting more than 10 days, or severe facial pain
Ear pain, a painful sore throat or a cough that will not go away
Symptoms in older adults, pregnant people or anyone with asthma, COPD, diabetes, heart disease or a weakened immune system

KEL Healthcare's acute care team treats sudden, non-emergency illness such as colds, flu and sinus or ear infections, and walk-ins are welcome. Confirm hours at your location first.

Call 911 or Go to the ER If

You have trouble breathing or shortness of breath
You have chest pain or pressure
You are confused or very hard to wake
You have a stiff neck with fever and severe headache
Lips or face turn blue, or a child cannot drink or is unusually limp

Conclusion

Colds, flu and sinus infections look alike, but timing, severity and a few key symptoms can help you choose the right next step. When in doubt, check in with a clinician.

If you need a same-day visit, schedule an appointment or see our locations. This article is for general information only and is not medical advice. In an emergency, call 911.