Common Symptoms of Flu
Get information about the flu signs, medications, and how to avoid getting the flu this season: vaccinations, hygiene practices, and more.
Written by Dr Shreya Sarkar
Last updated on 3rd Jul, 2025
Flu is a viral infection of the respiratory system that affects people around the world every year. It is caused by the influenza virus, which transmits through saliva when an infected person coughs, sneezes, or even speaks and releases droplets. It leads to significant discomfort and, in severe cases, serious health complications. So, it is important to diagnose flu symptoms early to start treatment and get better.
General Symptoms of the Flu
Flu is associated with numerous symptoms. Identifying these early can make it easy to manage this condition. Some of the key symptoms to watch for:
- Fever and Chills: A sudden fever is one of the most universal symptoms of flu. It is usually associated with chills and shaking, producing an uncomfortable feeling.
- Body Aches and Fatigue: Muscle and joint aches are typical during the flu. Such pains accompanied by weakness can turn even mere activities into a painful endeavour.
- Headache and Sore Throat: Those with the flu are likely to develop severe headaches. Also, a sore throat might make swallowing, speaking, or eating painful.
Respiratory Symptoms
Flu attacks the respiratory system, and people who have the flu find it difficult to breathe. Below are the respiratory problems that one should expect:
- Persistent Coughing and Throat Irritation: Flu usually causes a dry or productive cough. It can be relatively moderate at first but may flare up, causing throat irritation.
- Blocked Nose and Excessive Runny Nose: Flu often results in congestion in the nasal passages and a runny nose, making it hard and uncomfortable to breathe through the nose, especially while sleeping.
Gastrointestinal Symptoms
Though the flu is a respiratory illness, it can also lead to gastrointestinal complications. Here are the common digestive issues associated with the flu:
- Upset Stomach: Some gastrointestinal symptoms associated with flu include nausea and vomiting. These often result in dehydration, especially if accompanied by poor appetite.
- Diarrhoea: Some variations of the flu virus cause diarrhoea, making the flu even more uncomfortable, especially for children. It dehydrates the body. This symptom is rare but not negligible.
- Appetite Loss and Food Aversion: Most people with flu develop anorexia or reduced desire to eat food, implying that they lack the necessary energy to feed themselves adequately. This can worsen the feeling of fatigue and weakness.
Consult Top Doctors for Your Symptoms
Symptoms in Different Populations
Seasonal flu symptoms typically differ among different populations. So, it is important to understand how flu impacts to get early intervention.
Symptoms in Children
In children, the flu can present with certain symptoms that may be more severe or prolonged than in adults. Some key signs to look out for include:
- Consistent fever even after 48 hours and more severe body pains
- Vomiting and diarrhoea are more common
- Getting irritated and tired
- Risk of dehydration caused by gastrointestinal symptoms
Symptoms in Elderly Individuals
For elderly individuals, flu symptoms can be quite different, and complications may develop more rapidly. Watch for the following:
- Confusion or less consciousness
- Pneumonia or respiratory failure
- May have an atypical fever response
- Symptoms in Pregnant Women
- Pregnant women are more vulnerable to complications from the flu, so identifying symptoms early is crucial. Common symptoms in this group include:
- Severe respiratory distress
- Vomiting and diarrhoea
- Extreme body and headache
Differentiating Flu from Common Cold
While the flu symptoms are comparable with those of a common cold, they are not the same illness. Here are the differences:
- Flu: Signs/symptoms include high fever, general body aches and pains, fatigue, and severe headache.
- Common Cold: Symptoms are less severe mainly including a runny nose, mild cough, and nasal congestion.
- Flu: Symptoms appear out of the blue, and they get worse quickly.
- Common Cold: The symptoms begin to appear over a few days as the disease progresses.
When to Seek Medical Attention?
If you're unsure whether symptoms are from the flu or a cold, it’s important to know when to seek medical attention:
- Flu: See a Doctor if the signs such as breathing problems, chest pain, congestion, or high fever persist for more than seventy-two hours.
- Common Cold: No medical treatment is generally necessary except if the symptoms last more than 10 days or worsen.
Complications Arising from Flu
Flu usually resolves with rest and hydration, but it can be fatal, especially for those with chronic conditions.
Increased Risk of Pneumonia
The flu can cause either viral or bacterial pneumonia when in contact with susceptible persons like the elderly or patients with respiratory diseases.
- Symptoms: Excessive coughing, breathing problems, chest pain, very high body temperature, and lack of strength.
- Impact: Potential complications of pneumonia include chronic respiratory problems or deadly illnesses.
Worsening of Existing Chronic Conditions
Flu may make underlying medical conditions such as asthma, diabetes, and heart disease worse than they are.
- Symptoms: Worsening asthma symptoms, low or high blood sugar, or heart conditions.
- Management: Daily check-ups and physicians’ recommendations are required to maintain these risks.
Development of Sinus and Ear Infections
Flu may cause secondary bacterial infections, including sinusitis and ear infections.
- Symptoms: Pressure or pain in the sinuses, earache, drainage, and fever.
- Risk: Uncontrolled infections may cause further complications or take longer to recover.
Diagnosis and Testing for Flu
Early diagnosis of flu infection is important for proper treatment. Below are the key methods used for diagnosis:
- Rapid Influenza Diagnostic Tests (RIDTs): RIDTs pick up flu antigens from nasal or throat swabs. It takes 15 to 30 minutes to produce the results. These tests are very fast but may fail to detect the disease, particularly if used in the early stages of the infection.
- Molecular Flu Tests: The tests like PCR are highly accurate. They visualise the genetic material of the flu virus as opposed to serologic tests. These tests are utilised in healthcare and research facilities to give accurate data and separate flu variations.
- Viral Culture Tests: Viral culture tests involve growing the virus in a laboratory, which takes several days. This method is mostly applied for confirmation and strain differentiation.
Treatment Options
Flu treatment helps decrease the severity of the illness, symptoms, and possible complications. Some of the treatment options are:
- Antiviral Medications: Some drugs like oseltamivir (Tamiflu) and zanamivir (Relenza) may be administered within 48 hours after getting affected by flu to minimise the severity and duration of the flu signs if administered instantly.These medications decrease the possibility of the virus’s ability to multiply in the body.
- Over-the-counter Medications: You can take over-the-counter medications such as acetaminophen or ibuprofen to treat symptoms such as fever, body aches, and headaches. Decongestants and antihistamines can help relieve breathing and nasal congestion while coughing syrups help treat coughing.
- Home Remedies and Supportive Care: Adequate Sleep, water, and nutrition are key to recovery. Use a humidifier and saline nasal spray to clear up the congestion in the nose.
- Hospitalisation and Intensive Care: In extreme conditions, one may need to be hospitalised, primarily for those with comorbidity or those with increased susceptibility to complications. It may require intravenous fluids, oxygen therapy, and other respiratory support.
Prevention of Flu
It is important to avoid getting the flu and to help prevent passing it on to others. Vaccination is the best way to protect from the most common flu strains. However, measures of hygiene, including hand washing, proper mask-wearing when one has the flu or cold, and avoiding close contact with any person exhibiting flu or cold-like symptoms, greatly reduce the chances of getting infected. These preventive measures help prevent the sickness of the particular person and other people.
Conclusion
Recognising flu symptoms early is vital for timely treatment and preventing complications. By understanding its common signs, differentiating it from a cold, and seeking medical attention when necessary, individuals can manage it effectively.
Consult Top General Physicians
Consult Top Doctors for Your Symptoms
Dr. Lakshmi Sindhura Kakani
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10 Years • MBBS, MD (General medicine)
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Dr. Suraja Nutulapati
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(850+ Patients)
Dr. Shamim Anjum
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Dr Nikhat Shamim
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Kolkata
VIP MEDICAL SERVICE, Kolkata
Dr Vishwa Vijeth K.
Pulmonology Respiratory Medicine Specialist
8 Years • MBBS, MD ( Respiratory Medicine)
Bangalore
Apollo Clinic Bellandur, Bangalore
Consult Top General Physicians
Dr. Lakshmi Sindhura Kakani
General Physician/ Internal Medicine Specialist
10 Years • MBBS, MD (General medicine)
Visakhapatnam
Apollo 24|7 Clinic - Andhra Pradesh, Visakhapatnam
Dr. Suraja Nutulapati
General Physician/ Internal Medicine Specialist
10 Years • MBBS, MD (Internal Medicine)
Hyderabad
Apollo 24|7 Clinic, Hyderabad
(850+ Patients)
Dr. Shamim Anjum
Family Physician
15 Years • MBBS, M MED (Family Medicine)
Hyderabad
FAMILY CARE CLINIC, Hyderabad
Dr Nikhat Shamim
General Practitioner
4 Years • MBBS
Kolkata
VIP MEDICAL SERVICE, Kolkata
Dr Vishwa Vijeth K.
Pulmonology Respiratory Medicine Specialist
8 Years • MBBS, MD ( Respiratory Medicine)
Bangalore
Apollo Clinic Bellandur, Bangalore
