A concise reference for common illnesses including influenza (flu), the common cold (rhinovirus), COVID-19, and viral gastroenteritis. This page summarizes typical symptom onset windows and expected durations to help you quickly compare patterns and set expectations for recovery.
Each illness section lists individual symptoms with a short visual distribution and a brief explanatory line to make comparisons quickly; for example, flu commonly presents with rapid fever and body aches, while colds often begin with sore throat and congestion. Use these timelines to identify likely patterns, not to make a diagnosis.
These timelines are approximate and will vary by age, vaccination status, underlying conditions, and available treatments. If symptoms are severe, worsening, or include difficulty breathing, high fever, persistent vomiting, or signs of dehydration, seek medical care promptly.
Information here is for general guidance and not a substitute for professional medical advice. For the latest clinical guidance, consult public health authorities or your healthcare provider.
Influenza (Flu)
Overall illness duration: most people recover within 1-2
weeks; cough and fatigue may linger for several weeks in some
cases.
Fever
1-2 days after exposure; typical duration: 2-5 days (may be higher and longer in severe cases).
Cough
onset: often at symptom start; typical duration: 1-3 weeks, usually improving after the first week.
Sore throat
onset: often early alongside cough; typical duration: 2-5 days.
Body aches and fatigue
onset: early (1-2 days after exposure); typical duration: 3-7 days, though fatigue may persist longer.
Rhinovirus (Common Cold)
Overall illness duration: typically about 7-10 days, though some symptoms (like cough) can persist up to 2 weeks.
Sore throat
onset: commonly one of the first symptoms (within 1-2 days); typical duration: 1-3 days, often mild.
Runny or stuffy nose
onset: 1-3 days after exposure; typical duration: 4-10 days, sometimes longer with postnasal drip-related cough.
Sneezing
onset: early (1-2 days); typical duration: several days to a week.
Cough
onset: may begin a few days in as mucus drains; typical duration: up to 2 weeks, often milder than flu-related coughs.
COVID-19 (SARS-CoV-2)
Fever
Overall illness duration: mild cases often resolve in 1-2 weeks; more severe illness may last several weeks and a minority experience prolonged symptoms (post-acute or 'long' COVID lasting 12+ weeks).
onset: commonly 2-5 days after exposure; typical duration: 3-7 days in mild cases.
Dry cough
onset: often early with other symptoms; typical duration: 1-3 weeks, can persist longer.
Sore throat
onset: early; typical duration: 2-7 days.
Loss of taste or smell
onset: often within the first week; typical duration: days to weeks, sometimes longer.
Fatigue
onset: early; typical duration: 1-4 weeks, though some people experience prolonged fatigue.
Headache
onset: early; typical duration: several days.
Shortness of breath
onset: may occur early or develop later; duration is variable and severe cases require prompt medical attention.
Stomach Bug (Viral Gastroenteritis)
Overall illness duration: usually 1-3 days for most healthy adults; symptoms can last longer (up to a week or more) in young children, older adults, or immunocompromised people.
Nausea and vomiting
onset: typically 12-48 hours after exposure; typical duration: 24-48 hours, sometimes longer in vulnerable people.
Diarrhea
onset: often with or after vomiting; typical duration: 1-3 days, but can last longer depending on the virus and host factors.
Abdominal cramps
onset: concurrent with diarrhea; typical duration: 1-3 days.