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Influenza
Moderate
Influenza is a contagious respiratory illness caused by influenza viruses. It commonly develops suddenly and may cause fever, chills, cough, sore throat, muscle aches, headache, and marked fatigue. Some people, particularly young children, may also experience vomiting or diarrhea. Most healthy people recover without serious complications, but influenza can lead to pneumonia and other severe problems in older adults, young children, pregnant people, and individuals with certain chronic conditions or weakened immunity. Seasonal vaccination and appropriate infection-control measures help reduce illness and transmission.
Body System
Respiratory System
When to Seek Medical Attention
Influenza is often self-limited, but some people develop serious complications. Seek prompt medical assessment for worsening symptoms, dehydration, persistent high fever, or significant weakness, particularly in people at higher risk of complications. Emergency care is needed for severe breathing difficulty, chest pain, confusion, fainting, bluish lips or skin, or rapidly worsening illness.
Symptoms
4
Causes
1
Treatments
5
Diet
3
Overview
Influenza is a contagious respiratory illness caused by influenza viruses. It commonly develops suddenly and may cause fever, chills, cough, sore throat, muscle aches, headache, and marked fatigue. Some people, particularly young children, may also experience vomiting or diarrhea. Most healthy people recover without serious complications, but influenza can lead to pneumonia and other severe problems in older adults, young children, pregnant people, and individuals with certain chronic conditions or weakened immunity. Seasonal vaccination and appropriate infection-control measures help reduce illness and transmission.
Symptoms 4
Dry Cough
Fever
Increased Appetite
Muscle Weakness
Causes 1
Influenza is caused by infection with influenza viruses, particularly influenza A and influenza B viruses responsible for seasonal outbreaks. The viruses spread mainly through respiratory particles released when an infected person coughs, sneezes, talks, or breathes. Transmission can also occur when people touch contaminated surfaces and then touch their mouth, nose, or eyes. Influenza viruses continually change through genetic variation, which contributes to the appearance of different circulating strains and the need for updated seasonal vaccines.
Infection
Risk Factors
The risk of influenza is increased during periods when influenza viruses are circulating widely. Older adults, young children, pregnant people, and individuals with chronic heart, lung, kidney, metabolic, or neurological conditions may have a greater risk of serious complications. Weakened immunity can also increase risk. Close contact with infected people, crowded indoor environments, and inadequate ventilation can facilitate transmission. Lack of seasonal vaccination may increase susceptibility to circulating strains.
Diagnosis
Diagnosis is based on a patient's medical history,
symptoms, physical examination and, when necessary,
laboratory or imaging investigations.
Influenza can often be diagnosed clinically from symptoms and the pattern of illness during periods of active community transmission. Rapid influenza diagnostic tests may provide results quickly, although their ability to detect infection varies. Molecular tests, including rapid molecular assays and other laboratory methods, can provide more sensitive confirmation when testing is indicated. Testing is particularly useful when the result may affect treatment, infection-control decisions, or evaluation of people at higher risk of complications. The diagnosis should also consider other respiratory infections with similar symptoms.
Prevention
Key Prevention Tips
Annual influenza vaccination is an important measure for reducing the risk of influenza and its complications
Good hand hygiene, covering coughs and sneezes, improving indoor ventilation, and avoiding close contact with people who are ill can reduce transmission
People with influenza should stay home when sick when possible and follow local guidance about returning to normal activities
Higher-risk individuals should seek medical advice promptly when significant influenza symptoms develop because antiviral treatment may be most useful when started early
Prevention Guidance
Annual influenza vaccination is an important measure for reducing the risk of influenza and its complications. Good hand hygiene, covering coughs and sneezes, improving indoor ventilation, and avoiding close contact with people who are ill can reduce transmission. People with influenza should stay home when sick when possible and follow local guidance about returning to normal activities. Higher-risk individuals should seek medical advice promptly when significant influenza symptoms develop because antiviral treatment may be most useful when started early.
Reminder: Prevention recommendations should be tailored to your personal health status and risk factors.
Treatment & Management 5
Detailed treatment guidance is currently being prepared.
Detailed treatment guidance is currently being prepared.
Detailed treatment guidance is currently being prepared.
Detailed treatment guidance is currently being prepared.
Detailed treatment guidance is currently being prepared.
Medical Note: The treatment information provided is intended for educational purposes only.
Always consult a qualified healthcare professional before starting,
stopping, or changing any treatment.
Diet & Nutrition 3
Recommended Foods
Warm Soups
Provide hydration and comfort.
Fresh Fruits
Provide vitamins and antioxidants.
Herbal Tea
May soothe throat discomfort.
Foods to Avoid
Alcohol
May worsen dehydration.
Junk Food
Provides poor nutrition during illness.
Medical Nutrition Note: Diet recommendations are intended for general educational purposes and should be tailored to individual health needs by a qualified healthcare professional.
Frequently Asked Questions 5
Influenza is a contagious viral respiratory infection.
Fever, cough, sore throat and body aches are common.
It spreads through respiratory droplets.
Clinical evaluation and laboratory testing are used.
Annual vaccination and hygiene measures help prevention.
Helpful Tip: These answers provide general medical information.
Consult your healthcare provider for advice tailored to your condition.