Flu or cold? How to tell them apart and when to see a doctor
The differences between flu and a cold, who should get treated early, why antibiotics do not work for flu and the emergency warning signs.
At this time of year, almost everyone ends up with a stuffy nose at some point. The question is whether it is a cold that will pass on its own or a flu worth getting checked. The difference matters, especially for some people.
How to tell them apart
According to the CDC:
| Flu | Cold | |
|---|---|---|
| How it starts | Suddenly | Gradually |
| Fever | Common, lasts about 3 to 4 days | Rare |
| Body aches | Common and often severe | Slight |
| Headache and fatigue | Common | Less common |
| Sneezing and stuffy nose | Sometimes | Typical |
Other flu symptoms include chills, cough and sore throat. Vomiting and diarrhea are more common in children. And note: not everyone with flu has a fever.
Who should get treated early
The CDC recommend treating people with flu who are at higher risk of complications, such as those with asthma, diabetes or heart disease, as soon as possible with antivirals, which need a prescription.
Antivirals work best when started early, ideally within the first two days of symptoms. So if you are in a higher-risk group, do not wait to see whether it passes: call your doctor.
Most healthy people who get the flu have a mild illness and do not need antivirals.
Antibiotics do not work for flu
Flu and colds are caused by viruses, and antibiotics only work against bacteria. Taking them when you do not need them does not help and can cause side effects, such as allergic reactions or a gut infection called C. diff.
Stay home
If you have the flu, stay home and avoid contact with others except to get medical care. According to the CDC, you can go back to your activities once your symptoms are improving and you have gone at least 24 hours without a fever without using fever-reducing medicine.
Emergency warning signs
Get medical care right away if an adult has:
- Trouble breathing or shortness of breath.
- Ongoing pain or pressure in the chest or abdomen.
- Persistent dizziness, confusion or trouble waking up.
- Seizures, or is not urinating.
- Severe weakness, unsteadiness or muscle pain.
And if a child has:
- Fast or difficult breathing, or bluish lips or face.
- Signs of dehydration, such as no urine for 8 hours.
- Seizures, or is not alert when awake.
- Any fever if they are younger than 12 weeks.
At any age, also if fever or cough gets better and then comes back or gets worse.
How we handle it at the clinic
We treat flu, COVID, colds and infections, with same-week appointments. And the best protection is still the yearly vaccine: ask us about it at your next visit. In English or Spanish.
Sources
- Centers for Disease Control and Prevention (CDC). Signs and Symptoms of Flu.
- Centers for Disease Control and Prevention (CDC). Treatment of Flu.
This article is general information about our clinic and about flu and colds. It is not medical advice and does not replace a consultation with a professional. If you have a medical emergency, call 911.