Flu symptoms

Overview

Influenza is a viral respiratory illness that hits fast. Unlike a common cold that creeps up, the flu typically arrives within hours: high fever, deep body aches, exhaustion, and a dry cough are the hallmark combination. Most healthy adults recover in 5–7 days, though cough and fatigue can linger 2 weeks.

Symptoms to watch for

• Fever of 100–104°F, often with chills
• Body aches and headache — often severe
• Extreme fatigue that keeps you in bed
• Dry cough and sore throat
• Runny or stuffy nose
• Nausea or vomiting (more common in kids)

What else could this be?

• Common cold — milder, gradual, no severe body aches
• COVID-19 — loss of taste/smell more common, requires testing to distinguish
• Strep throat — throat pain dominates, no cough
• RSV — wheezing more prominent, especially in older adults

How it's diagnosed

A clinician can usually diagnose the flu clinically during flu season based on symptoms and timing. Rapid flu tests (nasal swab) confirm the diagnosis and guide antiviral decisions, especially if you're within 48 hours of onset or at high risk.

Treatment

Antivirals (oseltamivir/Tamiflu, baloxavir/Xofluza) can shorten flu by ~1 day and reduce complications if started within 48 hours. Otherwise: fluids, acetaminophen or ibuprofen for fever, rest, and isolation. High-risk patients (pregnant, over 65, immunocompromised, chronic lung/heart disease) benefit most from antivirals.

Frequently asked