Every fall and winter, the same question comes up after the first sneeze or sore throat: is this just a cold, or something more? Colds, the flu and COVID-19 are all caused by viruses that infect the nose, throat and lungs, and their symptoms overlap a lot. You cannot always tell them apart by symptoms alone, but there are some general patterns, and knowing them helps you decide when to rest at home, when to test and when to see a doctor.
The usual patterns
Common cold
- Comes on gradually.
- Sneezing, runny or stuffy nose and sore throat are the main symptoms.
- Fever is uncommon in adults and usually mild.
- You feel unwell but can usually carry on with daily life.
- Usually improves within about a week to ten days.
Flu (influenza)
- Comes on suddenly, often within hours.
- Fever, chills, body aches, headache and extreme tiredness are common.
- Cough and sore throat are common too.
- You often feel too unwell to get out of bed.
- Most people recover in one to two weeks, but tiredness can linger.
COVID-19
- Can come on gradually or quickly.
- Symptoms range from very mild to severe and can include fever, cough, sore throat, congestion, tiredness, headache and body aches.
- Loss of taste or smell can happen, though it has become less common with newer variants.
- Some people have long-lasting symptoms.
Because the symptoms overlap, testing is the only reliable way to know. Home tests for COVID-19, and combined tests for COVID-19 and flu, are widely available. The CDC has up-to-date guidance on respiratory viruses.
When to see a doctor quickly
Seek medical care right away if you or someone you care for has:
- Trouble breathing or shortness of breath.
- Chest pain or pressure.
- Confusion or difficulty staying awake.
- Bluish lips or face.
- Severe dehydration, such as not urinating.
- A fever that improves and then returns with a worse cough.
- Symptoms in an infant, an older adult or someone with a serious health condition that are getting worse.
Antiviral treatments for flu and COVID-19 work best when started early, usually within the first few days. If you are at higher risk because of age, pregnancy or a health condition, contact your doctor soon after symptoms start.
What actually helps at home
- Rest. Your body fights infection better when you are not pushing through.
- Fluids. Water, broth, herbal tea and oral rehydration drinks, especially with fever. See hydration and electrolytes.
- Honey for cough. Honey has reasonable evidence for easing coughs in adults and children over one year old. Never give honey to babies under one.
- Saltwater gargles for a sore throat.
- Humidifier or steam for congestion.
- Fever and pain relievers such as acetaminophen or ibuprofen, following the label and checking with your doctor if you have other conditions.
- Stay home to avoid spreading it, and wash your hands often.
What about supplements?
- Zinc lozenges, started within 24 hours of cold symptoms, may shorten a cold for some people. They can cause nausea and a bad taste. Avoid zinc nasal sprays, which have been linked to loss of smell. See zinc supplements guide.
- Vitamin C taken regularly may slightly shorten colds, but starting it after you get sick does not seem to help much.
- Vitamin D may slightly reduce the risk of respiratory infections in people who are low. See vitamin D and your immune system.
- Elderberry and echinacea have mixed evidence.
None of these treat the flu or COVID-19. See "immune support" supplements for the full rundown.
Prevention
- Vaccines for flu and COVID-19 are the most effective way to reduce severe illness. Talk to your doctor or pharmacist about what is recommended for you each season.
- Wash your hands often.
- Sleep well, stay active and eat a varied diet.
- Stay home when sick, and consider a mask in crowded places during peak season if you are at higher risk.
The bottom line
Colds usually come on slowly and stay mild, flu tends to hit suddenly and hard, and COVID-19 can look like either. Testing is the only way to be sure. Rest, fluids and honey help most people feel better, and zinc lozenges may shorten a cold. Know the warning signs, and do not hesitate to call a doctor if symptoms are severe or you are at higher risk.