Is Influenza the Same as a Cold?

Both are viral respiratory illnesses, but influenza (the flu) is not a “bad cold.” Influenza tends to start abruptly with high fever, chills, prominent muscle and body aches, severe fatigue, headache, and dry cough. Colds usually come on gradually with milder symptoms, runny/stuffy nose, and rarely cause high fever or serious complications.

Who Is at Higher Risk for Severe Flu?

• Adults ≥65 years, infants and young children
• Pregnant and postpartum people
• Chronic conditions (heart, lung, kidney, liver, diabetes, neurologic disease)
• Immunocompromised individuals
• Residents of long-term care facilities; people with obesity

Clinical Spectrum of Influenza

1) Mild influenza
– Mild–moderate fever and respiratory symptoms; most recover in 2–3 days with rest and fluids.

2) Influenza virus pneumonia
– Begins like typical influenza, then worsens within 1–3 days with high fever, worsening cough, chest pain, and breathlessness.
– May progress to respiratory failure and multiorgan dysfunction; antibiotics are ineffective unless there’s bacterial coinfection.
– More common in the very young, older adults, people with chronic disease, and the immunocompromised.

3) Neurologic involvement (meningitis/encephalitis)
– Altered consciousness, severe headache, vomiting, neck stiffness, seizures; rare but serious.

4) Cardiac involvement (myocarditis/pericarditis)
– Chest tightness or pain, palpitations; abnormal cardiac enzymes or ECG; can progress to heart failure.

5) Myositis and rhabdomyolysis (more common in children)
– Muscle pain and weakness, tenderness; dark/brown urine; markedly elevated CK and myoglobin.

6) Severe or critical influenza
– Severe disease: any of the following — persistent high fever >3 days with severe cough/sputum or chest pain; rapid breathing, dyspnea, cyanosis; altered mental status (slow reaction, drowsiness, agitation, seizures); severe vomiting/diarrhea with dehydration; pneumonia; marked worsening of underlying disease.
– Critical disease: respiratory failure; acute necrotizing encephalopathy; septic shock; multiorgan failure; or any condition requiring ICU-level care.

Red Flags — Seek Urgent Care

• Trouble breathing, rapid breathing, blue/gray lips
• Chest pain or pressure, new confusion, seizures, fainting
• Persistent high fever (>3 days) or sudden worsening after initial improvement
• Severe dehydration (very little urine, dizziness), inability to keep fluids down
• In infants: poor feeding, lethargy, irritability, apnea

Diagnosis

• Clinical assessment plus testing when available: rapid antigen tests, or preferably molecular (RT‑PCR) tests for higher sensitivity.
• Consider chest imaging and labs in severe presentations or high‑risk patients.

Treatment

• Start antivirals as soon as possible in hospitalized, severe, or high‑risk patients, even if >48 hours after onset. Options include neuraminidase inhibitors (e.g., oseltamivir; inhaled zanamivir when appropriate) or baloxavir in select cases.
• Supportive care: rest, fluids, antipyretics/analgesics (avoid aspirin in children and teens due to Reye syndrome).
• Monitor closely for complications. Use antibiotics only if there’s evidence of bacterial coinfection (e.g., secondary bacterial pneumonia).

Prevention

• Annual influenza vaccination for everyone eligible; critical for high‑risk groups and healthcare workers.
• Hand hygiene, respiratory etiquette, and staying home when febrile.
• Consider masks and improved ventilation during outbreaks or for vulnerable individuals.
• Post‑exposure antiviral prophylaxis may be considered for high‑risk exposures per local guidelines.

Return to Normal Activities

• Return once fever has resolved for at least 24 hours without fever‑reducing medicines and symptoms are improving.

Educational information only; not a substitute for medical advice. Seek care promptly for red‑flag symptoms or if you’re in a high‑risk group.