Fever

Fever is a temporary increase in body temperature that commonly occurs when the immune system responds to an infection or illness. Respiratory infections such as pneumonia, influenza, and tuberculosis can cause fever, sometimes along with cough, chills, sweating, or breathing difficulties.

Medically Reviewed
Dr. Nabila Zaheer Consultant Pulmonologist
Last Updated
Sep 03, 2026
Fever
2 min estimated read

Overview

Fever is a common symptom in which body temperature rises above the normal range. It is usually a response to an infection, although inflammation, certain medications, heat-related illness, and other medical conditions can also cause fever. In respiratory conditions, fever may occur when the body is fighting an infection such as pneumonia, influenza, bronchitis, or tuberculosis. The presence of fever together with cough, chest discomfort, shortness of breath, or other symptoms can help a healthcare professional determine the possible cause. The severity and duration of fever, as well as the symptoms occurring alongside it, are important when deciding whether medical evaluation is needed.

Causes

Common causes of fever include: Viral respiratory infections Influenza (flu) COVID-19 Pneumonia Bronchitis Tuberculosis Bacterial infections Other infections Inflammatory conditions Certain medications Heat-related illness Other underlying medical conditions

Risk Factors

Factors that may increase the likelihood of developing fever include: Exposure to people with infections Close contact with someone who is ill A weakened immune system Chronic medical conditions Recent surgery or medical procedures Travel to areas where certain infections are common Exposure to respiratory infections Poor infection-control practices

Diagnosis

A healthcare professional may measure body temperature and ask about the duration of the fever and other symptoms. Depending on the suspected cause, evaluation may include: Physical examination Temperature monitoring Blood tests Urine tests Chest X-ray Respiratory infection testing Tuberculosis testing when appropriate Other imaging or laboratory tests based on symptoms The appropriate tests depend on the person's age, symptoms, medical history, and suspected cause.

Treatment

Treatment depends on the underlying cause of the fever. General measures may include: Drinking adequate fluids Getting sufficient rest Wearing comfortable, lightweight clothing Treating the underlying infection or condition Using fever-reducing medication when appropriate and recommended If a bacterial infection is diagnosed, antibiotics may be prescribed when medically appropriate. Viral respiratory infections generally require supportive care unless specific antiviral treatment is indicated.

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Prevention

Some causes of fever can be reduced by: Washing hands regularly Avoiding close contact with people who are sick Covering coughs and sneezes Staying home when ill when possible Keeping recommended vaccinations up to date Avoiding smoking and respiratory irritants Following appropriate food and water safety practices Managing chronic medical conditions appropriately

Complications

Most short-term fevers resolve without complications. However, prolonged or very high fever can contribute to: Dehydration Weakness and fatigue Increased heart rate Increased breathing rate Worsening of an underlying medical condition The underlying cause of the fever may present more serious complications if left untreated.

When to See a Doctor

See a doctor if: Fever persists or repeatedly returns Fever is accompanied by a persistent cough You develop shortness of breath or chest discomfort You experience night sweats or unexplained weight loss You have persistent weakness or worsening symptoms You have a weakened immune system or significant underlying medical condition Seek urgent medical care if fever occurs with severe difficulty breathing, confusion, fainting, severe dehydration, seizures, severe chest pain, or other serious symptoms. For infants and young children, fever may require earlier medical assessment depending on age and associated symptoms.

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Frequently Asked Questions

Fever is a temporary rise in body temperature, often occurring when the immune system responds to an infection or illness. It is a common symptom of many respiratory and other medical conditions.

Fever can be caused by viral or bacterial infections, including influenza, COVID-19, pneumonia and other infections. It can also occur with inflammatory conditions, certain medications and heat-related illness.

Yes. Respiratory infections such as influenza, COVID-19, pneumonia and some other lung infections can cause fever, often along with symptoms such as cough, sore throat, fatigue or breathing difficulties.

No. Although infections are a common cause, fever can also occur because of inflammation, certain medications, heat-related illness and other medical conditions.

You should seek medical advice if fever persists or keeps returning, particularly if it occurs with persistent cough, shortness of breath, chest discomfort, night sweats, unexplained weight loss, significant weakness or worsening symptoms.

Yes. Fever is a common symptom of pneumonia. It may occur together with cough, phlegm, chest discomfort, fatigue or difficulty breathing.

Yes. Tuberculosis (TB) can cause fever, particularly when it affects the lungs. Other possible symptoms include a persistent cough, night sweats, fatigue and unexplained weight loss.

Yes. Fever and cough commonly occur together with respiratory infections such as influenza, COVID-19 and pneumonia. The combination and duration of symptoms can help a doctor determine the possible cause.

A doctor may review your symptoms and medical history and perform a physical examination. Depending on the situation, investigations may include blood tests, urine tests, chest X-ray, respiratory infection testing or tests for tuberculosis.

Rest, drink adequate fluids and avoid excessive clothing or overheating. Fever-reducing medicines may be appropriate for some people when used according to medical advice and the product instructions. Treatment should also address the underlying cause when identified.

Seek urgent medical attention if fever is accompanied by severe difficulty breathing, confusion, fainting, seizures, severe chest pain, severe dehydration or a rapid deterioration in overall condition.

Some causes of fever can be reduced through good hand hygiene, avoiding close contact with people who are sick, practicing cough and sneeze etiquette, staying home when ill, keeping vaccinations up to date and following appropriate food and water safety practices.

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