Cold vs Flu vs COVID: Symptoms Compared, When to Test and When Treatment Helps

Written by Naurah Gaspard, DNP, FNP-C, FNP-BC · Medically reviewed by Cherlie Joseph, MSN, FNP-BC · Updated November 2026

A cold usually starts slowly with a sore throat and runny nose and stays mild. Flu hits suddenly with fever, body aches and exhaustion. COVID-19 can look like either, and a new loss of taste or smell points toward COVID. Because symptoms overlap, a test is the only reliable way to tell flu from COVID, and that matters because antiviral treatment works best when started early.

Symptoms side-by-side

Symptom	Cold	Flu	COVID-19
Onset	Gradual	Sudden, often within hours	Gradual or sudden
Fever	Rare or low	Common, can be high (not everyone)	Common
Body aches, chills	Mild	Common, often severe	Common
Fatigue	Mild	Intense, can last weeks	Common, can linger
Sneezing, stuffy nose	Very common	Sometimes	Sometimes
Sore throat	Common, often first	Sometimes	Common
Cough	Mild to moderate	Common, dry	Common
New loss of taste or smell	Rare (from stuffiness)	Rare	More frequent than with flu
Shortness of breath	Uncommon	Possible	Possible

The CDC is clear that symptoms alone can't reliably separate flu from COVID-19. RSV, another common winter virus, also causes cold-like symptoms and can be more serious in adults over 60 and people with heart or lung disease.

How fast they start and how long you're contagious

• Cold: symptoms usually begin 1 to 3 days after exposure and last about 7 to 10 days. You are most contagious in the first few days.
• Flu: symptoms start 1 to 4 days after exposure. You can spread flu about a day before symptoms begin, and adults are most contagious in the first 3 days of illness.
• COVID-19: symptoms usually start 2 to 5 days after exposure, but it can take up to 14 days. Spread can begin 2 to 3 days before symptoms, and people are contagious for about 8 days on average after symptoms start.

A practical rule for all three: stay home while you have a fever and for at least 24 hours after it goes away without fever-reducing medicine and you are feeling better. For the next few days, wear a mask around others and wash your hands often.

When and how to test

Testing is most useful when the result could change what you do, such as starting an antiviral, protecting a high-risk family member, or deciding when to return to work.

• Home combination tests that check for both flu and COVID-19 are sold at pharmacies. They give results in minutes.
• Test early but repeat if negative. Home antigen tests can miss early infection. If your first COVID test is negative and you still have symptoms, test again in 48 hours.
• Pharmacy or lab PCR tests are more sensitive if you need a firm answer.

Having flu and COVID at the same time is uncommon but possible, and combined infection can be more severe.

Treatment: what helps each one

Colds have no antiviral treatment. Rest, fluids, saline spray, honey for cough, and acetaminophen or ibuprofen as the label directs are the mainstays. Antibiotics do not help viral infections.

Flu can be treated with prescription antivirals such as oseltamivir (Tamiflu) or baloxavir (Xofluza). They work best when started within 48 hours of symptoms and can shorten illness by about a day and lower the risk of complications. The CDC recommends treatment as early as possible for people at higher risk, even after 48 hours.

COVID-19 antivirals such as nirmatrelvir-ritonavir (Paxlovid) are for people with mild to moderate illness who are more likely to get very sick. Treatment must start within 5 to 7 days of symptoms, depending on the medicine. Paxlovid interacts with many common medicines, so a provider needs your full medication list.

For all three, avoid oral phenylephrine decongestants, which the FDA found do not work, and check with a provider before using decongestants if you have high blood pressure.

Who should get checked quickly

Contact a provider soon after symptoms start, so treatment can begin in time, if you:

• Are 65 or older
• Are pregnant or gave birth in the last 2 weeks
• Have asthma, COPD, diabetes, heart disease, kidney or liver disease
• Have a weakened immune system
• Have obesity (BMI of 40 or higher is especially high risk for flu complications)

Frequently asked questions

How can I tell if I have the flu or a cold?

Flu usually starts suddenly with fever, chills, body aches and exhaustion. A cold builds slowly with a sore throat, sneezing and a stuffy nose, and you can usually keep going. A flu test confirms it.

Does loss of taste or smell mean COVID?

A new loss of taste or smell is more common with COVID-19 than with flu, but not everyone with COVID has it. A heavily stuffed nose from a cold can also dull smell. Testing is the best way to know.

Can you get antivirals online?

Yes, in many cases. A nurse practitioner can review your symptoms, test results and health history through a telehealth visit and send a prescription to your pharmacy if an antiviral is appropriate.

Sources

• CDC: Similarities and Differences between Flu and COVID-19
• CDC: Influenza Antiviral Medications, Summary for Clinicians

Keep reading

• Sinus infection vs cold: how to tell the difference
• Flu treatment: Tamiflu, Xofluza and what to expect
• Nasal spray guide: which spray to use
• Browse all conditions and treatments A to Z

This article is for general education and is not a substitute for medical advice. Treatment, including any prescription, is decided by a licensed provider after reviewing your health history. OurTopClinic is not for emergencies; if you have a medical emergency, call 911. OurTopClinic serves adults located in Florida, New Mexico, Oregon and Washington. Learn more at ourtopclinic.com.