India
Infectious Diseases · 4 min read

Flu

Learn about Flu, its reported features, relevant specialists, and questions to discuss at a medical consultation.

Also known as: Grippe; Influenza; Seasonal flu

Compiled from public sources
Text selected and arranged from MedlinePlus (US National Library of Medicine) health topic. It describes the condition as those sources do; it has not been rewritten for India.
01 Oct 2026
Not medically reviewed
No registered doctor has reviewed this page. Use it to decide who to see and what to ask — not to diagnose or treat.
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This is not medical advice. If symptoms are severe, sudden or getting worse, call 112 (or 108 for an ambulance) or go to the nearest emergency department.

The sources compiled here do not cover: prevalence. Ask the treating doctor about these.

What is the flu?

From: MedlinePlus, National Library of Medicine

The flu, also called influenza, is a respiratory infection caused by viruses. Each year, millions of Americans get sick with the flu. Sometimes it causes mild illness. But it can also be serious or even deadly, especially for people over 65, newborn babies, and people with certain chronic illnesses.

What causes the flu?

From: MedlinePlus, National Library of Medicine

The flu is caused by flu viruses that spread from person to person. When someone with the flu coughs, sneezes, or talks, they spray tiny droplets. These droplets can land in the mouths or noses of people who are nearby. Less often, a person may get flu by touching a surface or object that has flu virus on it and then touching their own mouth, nose, or possibly their eyes.

What are the symptoms of the flu?

From: MedlinePlus, National Library of Medicine

Symptoms of the flu come on suddenly and may include:

Some people may also have vomiting and diarrhea. This is more common in children.

Sometimes people have trouble figuring out whether they have a cold or the flu. There are differences between them:

Signs and Symptoms Cold Flu Start of symptoms Slowly Suddenly Fever Rarely Usually Aches Sometimes (slight) Usually Fatigue, weakness Sometimes Usually Headache Rarely Common Stuffy nose, sneezing, or sore throat Common Sometimes

Sometimes people say that they have a "flu" when they really have something else. For example, "stomach flu" isn't the flu; it's gastroenteritis.

  • Fever or feeling feverish/chills
  • Cough
  • Sore throat
  • Runny or stuffy nose
  • Muscle or body aches
  • Headaches
  • Fatigue (tiredness)

What other problems can the flu cause?

From: MedlinePlus, National Library of Medicine

Some people who get the flu will develop complications. Some of these complications can be serious or even life-threatening. They include:

The flu also can make chronic health problems worse. For example, people with asthma may have asthma attacks while they have flu.

Certain people are more likely to have complications from the flu, including:

  • Bronchitis
  • Ear infection
  • Sinus infection
  • Pneumonia
  • Inflammation of the heart (myocarditis), brain (encephalitis), or muscle tissues (myositis, rhabdomyolysis)
  • Adults 65 and older
  • Pregnant women
  • Children younger than 5
  • People with certain chronic health conditions, such as asthma, diabetes, and heart disease

How is the flu diagnosed?

From: MedlinePlus, National Library of Medicine

To diagnose the flu, health care providers will first do a medical history and ask about your symptoms. There are several tests for the flu. For the tests, your provider will swipe the inside of your nose or the back of your throat with a swab. Then the swab will be tested for the flu virus.

Some tests are quick and give results in 15-20 minutes. But these tests are not as accurate as other flu tests. These other tests can give you the results in one hour or several hours.

What are the treatments for the flu?

From: MedlinePlus, National Library of Medicine

Most people with the flu recover on their own without medical care. People with mild cases of the flu should stay home and avoid contact with others, except to get medical care.

But if you have symptoms of flu and are in a high risk group or are very sick or worried about your illness, contact your health care provider. You might need antiviral medicines to treat your flu. Antiviral medicines can make the illness milder and shorten the time you are sick. They also can prevent serious flu complications. They usually work best when you start taking them within 2 days of getting sick.

Can the flu be prevented?

From: MedlinePlus, National Library of Medicine

The best way to prevent the flu is to get a flu vaccine every year. But it's also important to have good health habits like covering your cough and washing your hands often. This can help stop the spread of germs and prevent the flu.

Which doctor should you see?

The suggested department for discussing Flu is Infectious Diseases, with a general physician / infectious disease specialist as the relevant type of clinician. General physician / Family Medicine; paediatrician for children. Referral depends on symptoms.

This is an editorial referral starting point. The appropriate clinic depends on the person’s age, symptoms, previous diagnosis and local services. The first clinician can decide whether another specialty or a team is needed; a department label does not confirm the diagnosis.

How to prepare for an assessment

Bring a short timeline of the main symptoms: when they first appeared, whether they are constant or episodic, what seems to change them, and how they affect daily activities. Include previous reports, discharge summaries, current medicines and supplements, allergies, and any relevant family history. A dated record is more useful than trying to match every feature in an online article.

Ask the clinician what is already established and what remains uncertain. If a test is suggested, ask what question it answers, what its limitations are and how the result would change the next step. The information here is not an instruction to arrange every possible test. In children, bring growth, developmental and school information if it is relevant to the concern.

  • Which exposure or organism is suspected, and what evidence would confirm it?
  • Are precautions, vaccination or advice for close contacts relevant to this infection?
  • What should happen if symptoms worsen or do not improve as expected?

Treatment discussions and follow-up

Where the source describes treatments, these are an overview of possible care, not a prescription for an individual. Ask which option applies to the confirmed diagnosis, what benefit is expected, what adverse effects to watch for and how progress will be assessed. Availability, approvals and local practice can differ from the country described in the source.

Before leaving the appointment, clarify the next review date, who will communicate results, and whom to contact if the situation changes. Discuss difficulties with sleep, work, school, mobility, eating or emotional wellbeing when these are relevant. Practical support may require coordination between the treating clinician and other services.

When to seek emergency help

Severe breathing difficulty, collapse, new stroke-like symptoms, a seizure that is prolonged or repeated without recovery, uncontrolled major bleeding, or an immediate risk of self-harm require emergency help. In India, call 112 or reach the nearest emergency department. This is a general, non-exhaustive warning list; it is not a condition-specific triage tool.

Find a doctor for Flu

This condition is usually assessed by an infectious disease specialist. Every profile shows the doctor’s registration and what has been checked.

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Sources

Source: MedlinePlus, National Library of Medicine. Orphadata Science: Free access data from Orphanet. © INSERM 1999; July 2026 data, CC BY 4.0. This product uses the Human Phenotype Ontology (hp/releases/2026-09-01). Only sources listed for this article apply. Source material has been selected and arranged; HPO definitions are reproduced without alteration. No source organisation endorses this compilation. Köhler S et al. The Human Phenotype Ontology project: linking molecular biology and disease through phenotype data. Nucleic Acids Research 2014;42(D1):D966–D974. doi:10.1093/nar/gkt1026.

General information, not advice about your situation. Errors can be reported through the corrections process. Reference TDI-C-0941.