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Influenza (Flu)

Influenza, commonly known as "the flu," is a highly contagious viral infection of the respiratory tract. Although the flu affects both sexes and all age groups, kids tend to get it more often than adults. The illness even has its own season — from November to April, with most cases occurring between late December and early March.

Signs and Symptoms

The flu is often confused with the common cold, but flu symptoms are usually more severe than the typical sneezing and stuffiness of a cold.

Symptoms of the flu may include:

• fever
• chills
• headache
• muscle aches
• dizziness
• loss of appetite
• tiredness
• cough
• sore throat
• runny nose
• nausea or vomiting
• weakness
• ear pain
• diarrhea

Infants with the flu may simply seem sick all of a sudden or "just don't look right." The flu discussed here is not the same strain of virus as the avian flu.

Duration

After 5 days, fever and other symptoms have usually disappeared, but a cough and weakness may continue. All symptoms are usually gone within a week or two. However, it's important to treat the flu seriously because it can lead to pneumonia and other life-threatening complications, particularly in infants, senior citizens, and people with long-term health problems.

Contagiousness

Spread by virus-infected droplets that are coughed or sneezed into the air, the flu is contagious. People infected with the flu are contagious from a day before they feel sick until their symptoms have resolved (usually about 1 week for adults, but can be up to 2 weeks for young kids).

The flu usually occurs in small outbreaks, but epidemics tend to occur every several years. Epidemics (when the illness spreads rapidly and affects many people in an area at the same time) peak within 2 or 3 weeks after the first cases occur

About the Flu Vaccine

The flu Larissa Hirsch, MD
Date reviewed: October 2007

Influenza (Flu)

Influenza, commonly known as "the flu," is a highly contagious viral infection of the respiratory tract. Although the flu affects both sexes and all age groups, kids tend to get it more often than adults. The illness even has its own season — from November to April, with most cases occurring between late December and early March.

Signs and Symptoms

The flu is often confused with the common cold, but flu symptoms are usually more severe than the typical sneezing and stuffiness of a cold.

Symptoms of the flu may include:

• fever
• chills
• headache
• muscle aches
• dizziness
• loss of appetite
• tiredness
• cough
• sore throat
• runny nose
• nausea or vomiting
• weakness
• ear pain
• diarrhea

Infants with the flu may simply seem sick all of a sudden or "just don't look right." The flu discussed here is not the same strain of virus as the avian flu.

Duration

After 5 days, fever and other symptoms have usually disappeared, but a cough and weakness may continue. All symptoms are usually gone within a week or two. However, it's important to treat the flu seriously because it can lead to pneumonia and other life-threatening complications, particularly in infants, senior citizens, and people with long-term health problems.

Contagiousness

Spread by virus-infected droplets that are coughed or sneezed into the air, the flu is contagious. People infected with the flu are contagious from a day before they feel sick until their symptoms have resolved (usually about 1 week for adults, but can be up to 2 weeks for young kids).

The flu usually occurs in small outbreaks, but epidemics tend to occur every several years. Epidemics (when the illness spreads rapidly and affects many people in an area at the same time) peak within 2 or 3 weeks after the first cases occur

About the Flu Vaccine

The flu Larissa Hirsch, MD
Date reviewed: October 2007

Influenza (Flu)

Influenza, commonly known as "the flu," is a highly contagious viral infection of the respiratory tract. Although the flu affects both sexes and all age groups, kids tend to get it more often than adults. The illness even has its own season — from November to April, with most cases occurring between late December and early March.

Signs and Symptoms

The flu is often confused with the common cold, but flu symptoms are usually more severe than the typical sneezing and stuffiness of a cold.

Symptoms of the flu may include:

• fever
• chills
• headache
• muscle aches
• dizziness
• loss of appetite
• tiredness
• cough
• sore throat
• runny nose
• nausea or vomiting
• weakness
• ear pain
• diarrhea

Infants with the flu may simply seem sick all of a sudden or "just don't look right." The flu discussed here is not the same strain of virus as the avian flu.

Duration

After 5 days, fever and other symptoms have usually disappeared, but a cough and weakness may continue. All symptoms are usually gone within a week or two. However, it's important to treat the flu seriously because it can lead to pneumonia and other life-threatening complications, particularly in infants, senior citizens, and people with long-term health problems.

Contagiousness

Spread by virus-infected droplets that are coughed or sneezed into the air, the flu is contagious. People infected with the flu are contagious from a day before they feel sick until their symptoms have resolved (usually about 1 week for adults, but can be up to 2 weeks for young kids).

The flu usually occurs in small outbreaks, but epidemics tend to occur every several years. Epidemics (when the illness spreads rapidly and affects many people in an area at the same time) peak within 2 or 3 weeks after the first cases occur

About the Flu Vaccine

The flu Larissa Hirsch, MD
Date reviewed: October 2007

Influenza (Flu)

Influenza, commonly known as "the flu," is a highly contagious viral infection of the respiratory tract. Although the flu affects both sexes and all age groups, kids tend to get it more often than adults. The illness even has its own season — from November to April, with most cases occurring between late December and early March.

Signs and Symptoms

The flu is often confused with the common cold, but flu symptoms are usually more severe than the typical sneezing and stuffiness of a cold.

Symptoms of the flu may include:

• fever
• chills
• headache
• muscle aches
• dizziness
• loss of appetite
• tiredness
• cough
• sore throat
• runny nose
• nausea or vomiting
• weakness
• ear pain
• diarrhea

Infants with the flu may simply seem sick all of a sudden or "just don't look right." The flu discussed here is not the same strain of virus as the avian flu.

Duration

After 5 days, fever and other symptoms have usually disappeared, but a cough and weakness may continue. All symptoms are usually gone within a week or two. However, it's important to treat the flu seriously because it can lead to pneumonia and other life-threatening complications, particularly in infants, senior citizens, and people with long-term health problems.

Contagiousness

Spread by virus-infected droplets that are coughed or sneezed into the air, the flu is contagious. People infected with the flu are contagious from a day before they feel sick until their symptoms have resolved (usually about 1 week for adults, but can be up to 2 weeks for young kids).

The flu usually occurs in small outbreaks, but epidemics tend to occur every several years. Epidemics (when the illness spreads rapidly and affects many people in an area at the same time) peak within 2 or 3 weeks after the first cases occur

About the Flu Vaccine

The flu Larissa Hirsch, MD
Date reviewed: October 2007

Influenza (Flu)

Influenza, commonly known as "the flu," is a highly contagious viral infection of the respiratory tract. Although the flu affects both sexes and all age groups, kids tend to get it more often than adults. The illness even has its own season — from November to April, with most cases occurring between late December and early March.

Signs and Symptoms

The flu is often confused with the common cold, but flu symptoms are usually more severe than the typical sneezing and stuffiness of a cold.

Symptoms of the flu may include:

• fever
• chills
• headache
• muscle aches
• dizziness
• loss of appetite
• tiredness
• cough
• sore throat
• runny nose
• nausea or vomiting
• weakness
• ear pain
• diarrhea

Infants with the flu may simply seem sick all of a sudden or "just don't look right." The flu discussed here is not the same strain of virus as the avian flu.

Duration

After 5 days, fever and other symptoms have usually disappeared, but a cough and weakness may continue. All symptoms are usually gone within a week or two. However, it's important to treat the flu seriously because it can lead to pneumonia and other life-threatening complications, particularly in infants, senior citizens, and people with long-term health problems.

Contagiousness

Spread by virus-infected droplets that are coughed or sneezed into the air, the flu is contagious. People infected with the flu are contagious from a day before they feel sick until their symptoms have resolved (usually about 1 week for adults, but can be up to 2 weeks for young kids).

The flu usually occurs in small outbreaks, but epidemics tend to occur every several years. Epidemics (when the illness spreads rapidly and affects many people in an area at the same time) peak within 2 or 3 weeks after the first cases occur

About the Flu Vaccine

The flu Larissa Hirsch, MD
Date reviewed: October 2007

Influenza (Flu)

Influenza, commonly known as "the flu," is a highly contagious viral infection of the respiratory tract. Although the flu affects both sexes and all age groups, kids tend to get it more often than adults. The illness even has its own season — from November to April, with most cases occurring between late December and early March.

Signs and Symptoms

The flu is often confused with the common cold, but flu symptoms are usually more severe than the typical sneezing and stuffiness of a cold.

Symptoms of the flu may include:

• fever
• chills
• headache
• muscle aches
• dizziness
• loss of appetite
• tiredness
• cough
• sore throat
• runny nose
• nausea or vomiting
• weakness
• ear pain
• diarrhea

Infants with the flu may simply seem sick all of a sudden or "just don't look right." The flu discussed here is not the same strain of virus as the avian flu.

Duration

After 5 days, fever and other symptoms have usually disappeared, but a cough and weakness may continue. All symptoms are usually gone within a week or two. However, it's important to treat the flu seriously because it can lead to pneumonia and other life-threatening complications, particularly in infants, senior citizens, and people with long-term health problems.

Contagiousness

Spread by virus-infected droplets that are coughed or sneezed into the air, the flu is contagious. People infected with the flu are contagious from a day before they feel sick until their symptoms have resolved (usually about 1 week for adults, but can be up to 2 weeks for young kids).

The flu usually occurs in small outbreaks, but epidemics tend to occur every several years. Epidemics (when the illness spreads rapidly and affects many people in an area at the same time) peak within 2 or 3 weeks after the first cases occur

About the Flu Vaccine

The flu Larissa Hirsch, MD
Date reviewed: October 2007

Influenza (Flu)

Influenza, commonly known as "the flu," is a highly contagious viral infection of the respiratory tract. Although the flu affects both sexes and all age groups, kids tend to get it more often than adults. The illness even has its own season — from November to April, with most cases occurring between late December and early March.

Signs and Symptoms

The flu is often confused with the common cold, but flu symptoms are usually more severe than the typical sneezing and stuffiness of a cold.

Symptoms of the flu may include:

• fever
• chills
• headache
• muscle aches
• dizziness
• loss of appetite
• tiredness
• cough
• sore throat
• runny nose
• nausea or vomiting
• weakness
• ear pain
• diarrhea

Infants with the flu may simply seem sick all of a sudden or "just don't look right." The flu discussed here is not the same strain of virus as the avian flu.

Duration

After 5 days, fever and other symptoms have usually disappeared, but a cough and weakness may continue. All symptoms are usually gone within a week or two. However, it's important to treat the flu seriously because it can lead to pneumonia and other life-threatening complications, particularly in infants, senior citizens, and people with long-term health problems.

Contagiousness

Spread by virus-infected droplets that are coughed or sneezed into the air, the flu is contagious. People infected with the flu are contagious from a day before they feel sick until their symptoms have resolved (usually about 1 week for adults, but can be up to 2 weeks for young kids).

The flu usually occurs in small outbreaks, but epidemics tend to occur every several years. Epidemics (when the illness spreads rapidly and affects many people in an area at the same time) peak within 2 or 3 weeks after the first cases occur

About the Flu Vaccine

The flu Larissa Hirsch, MD
Date reviewed: October 2007

Influenza (Flu)

Influenza, commonly known as "the flu," is a highly contagious viral infection of the respiratory tract. Although the flu affects both sexes and all age groups, kids tend to get it more often than adults. The illness even has its own season — from November to April, with most cases occurring between late December and early March.

Signs and Symptoms

The flu is often confused with the common cold, but flu symptoms are usually more severe than the typical sneezing and stuffiness of a cold.

Symptoms of the flu may include:

• fever
• chills
• headache
• muscle aches
• dizziness
• loss of appetite
• tiredness
• cough
• sore throat
• runny nose
• nausea or vomiting
• weakness
• ear pain
• diarrhea

Infants with the flu may simply seem sick all of a sudden or "just don't look right." The flu discussed here is not the same strain of virus as the avian flu.

Duration

After 5 days, fever and other symptoms have usually disappeared, but a cough and weakness may continue. All symptoms are usually gone within a week or two. However, it's important to treat the flu seriously because it can lead to pneumonia and other life-threatening complications, particularly in infants, senior citizens, and people with long-term health problems.

Contagiousness

Spread by virus-infected droplets that are coughed or sneezed into the air, the flu is contagious. People infected with the flu are contagious from a day before they feel sick until their symptoms have resolved (usually about 1 week for adults, but can be up to 2 weeks for young kids).

The flu usually occurs in small outbreaks, but epidemics tend to occur every several years. Epidemics (when the illness spreads rapidly and affects many people in an area at the same time) peak within 2 or 3 weeks after the first cases occur

About the Flu Vaccine

The flu Larissa Hirsch, MD
Date reviewed: October 2007

Influenza (Flu)

Influenza, commonly known as "the flu," is a highly contagious viral infection of the respiratory tract. Although the flu affects both sexes and all age groups, kids tend to get it more often than adults. The illness even has its own season — from November to April, with most cases occurring between late December and early March.

Signs and Symptoms

The flu is often confused with the common cold, but flu symptoms are usually more severe than the typical sneezing and stuffiness of a cold.

Symptoms of the flu may include:

• fever
• chills
• headache
• muscle aches
• dizziness
• loss of appetite
• tiredness
• cough
• sore throat
• runny nose
• nausea or vomiting
• weakness
• ear pain
• diarrhea

Infants with the flu may simply seem sick all of a sudden or "just don't look right." The flu discussed here is not the same strain of virus as the avian flu.

Duration

After 5 days, fever and other symptoms have usually disappeared, but a cough and weakness may continue. All symptoms are usually gone within a week or two. However, it's important to treat the flu seriously because it can lead to pneumonia and other life-threatening complications, particularly in infants, senior citizens, and people with long-term health problems.

Contagiousness

Spread by virus-infected droplets that are coughed or sneezed into the air, the flu is contagious. People infected with the flu are contagious from a day before they feel sick until their symptoms have resolved (usually about 1 week for adults, but can be up to 2 weeks for young kids).

The flu usually occurs in small outbreaks, but epidemics tend to occur every several years. Epidemics (when the illness spreads rapidly and affects many people in an area at the same time) peak within 2 or 3 weeks after the first cases occur

About the Flu Vaccine

The flu Larissa Hirsch, MD
Date reviewed: October 2007

Influenza (Flu)

Influenza, commonly known as "the flu," is a highly contagious viral infection of the respiratory tract. Although the flu affects both sexes and all age groups, kids tend to get it more often than adults. The illness even has its own season — from November to April, with most cases occurring between late December and early March.

Signs and Symptoms

The flu is often confused with the common cold, but flu symptoms are usually more severe than the typical sneezing and stuffiness of a cold.

Symptoms of the flu may include:

• fever
• chills
• headache
• muscle aches
• dizziness
• loss of appetite
• tiredness
• cough
• sore throat
• runny nose
• nausea or vomiting
• weakness
• ear pain
• diarrhea

Infants with the flu may simply seem sick all of a sudden or "just don't look right." The flu discussed here is not the same strain of virus as the avian flu.

Duration

After 5 days, fever and other symptoms have usually disappeared, but a cough and weakness may continue. All symptoms are usually gone within a week or two. However, it's important to treat the flu seriously because it can lead to pneumonia and other life-threatening complications, particularly in infants, senior citizens, and people with long-term health problems.

Contagiousness

Spread by virus-infected droplets that are coughed or sneezed into the air, the flu is contagious. People infected with the flu are contagious from a day before they feel sick until their symptoms have resolved (usually about 1 week for adults, but can be up to 2 weeks for young kids).

The flu usually occurs in small outbreaks, but epidemics tend to occur every several years. Epidemics (when the illness spreads rapidly and affects many people in an area at the same time) peak within 2 or 3 weeks after the first cases occur

About the Flu Vaccine

The flu Larissa Hirsch, MD
Date reviewed: October 2007

Influenza (Flu)

Influenza, commonly known as "the flu," is a highly contagious viral infection of the respiratory tract. Although the flu affects both sexes and all age groups, kids tend to get it more often than adults. The illness even has its own season — from November to April, with most cases occurring between late December and early March.

Signs and Symptoms

The flu is often confused with the common cold, but flu symptoms are usually more severe than the typical sneezing and stuffiness of a cold.

Symptoms of the flu may include:

• fever
• chills
• headache
• muscle aches
• dizziness
• loss of appetite
• tiredness
• cough
• sore throat
• runny nose
• nausea or vomiting
• weakness
• ear pain
• diarrhea

Infants with the flu may simply seem sick all of a sudden or "just don't look right." The flu discussed here is not the same strain of virus as the avian flu.

Duration

After 5 days, fever and other symptoms have usually disappeared, but a cough and weakness may continue. All symptoms are usually gone within a week or two. However, it's important to treat the flu seriously because it can lead to pneumonia and other life-threatening complications, particularly in infants, senior citizens, and people with long-term health problems.

Contagiousness

Spread by virus-infected droplets that are coughed or sneezed into the air, the flu is contagious. People infected with the flu are contagious from a day before they feel sick until their symptoms have resolved (usually about 1 week for adults, but can be up to 2 weeks for young kids).

The flu usually occurs in small outbreaks, but epidemics tend to occur every several years. Epidemics (when the illness spreads rapidly and affects many people in an area at the same time) peak within 2 or 3 weeks after the first cases occur

About the Flu Vaccine

The flu Larissa Hirsch, MD
Date reviewed: October 2007

Influenza (Flu)

Influenza, commonly known as "the flu," is a highly contagious viral infection of the respiratory tract. Although the flu affects both sexes and all age groups, kids tend to get it more often than adults. The illness even has its own season — from November to April, with most cases occurring between late December and early March.

Signs and Symptoms

The flu is often confused with the common cold, but flu symptoms are usually more severe than the typical sneezing and stuffiness of a cold.

Symptoms of the flu may include:

• fever
• chills
• headache
• muscle aches
• dizziness
• loss of appetite
• tiredness
• cough
• sore throat
• runny nose
• nausea or vomiting
• weakness
• ear pain
• diarrhea

Infants with the flu may simply seem sick all of a sudden or "just don't look right." The flu discussed here is not the same strain of virus as the avian flu.

Duration

After 5 days, fever and other symptoms have usually disappeared, but a cough and weakness may continue. All symptoms are usually gone within a week or two. However, it's important to treat the flu seriously because it can lead to pneumonia and other life-threatening complications, particularly in infants, senior citizens, and people with long-term health problems.

Contagiousness

Spread by virus-infected droplets that are coughed or sneezed into the air, the flu is contagious. People infected with the flu are contagious from a day before they feel sick until their symptoms have resolved (usually about 1 week for adults, but can be up to 2 weeks for young kids).

The flu usually occurs in small outbreaks, but epidemics tend to occur every several years. Epidemics (when the illness spreads rapidly and affects many people in an area at the same time) peak within 2 or 3 weeks after the first cases occur

About the Flu Vaccine

The flu Larissa Hirsch, MD
Date reviewed: October 2007

Influenza (Flu)

Influenza, commonly known as "the flu," is a highly contagious viral infection of the respiratory tract. Although the flu affects both sexes and all age groups, kids tend to get it more often than adults. The illness even has its own season — from November to April, with most cases occurring between late December and early March.

Signs and Symptoms

The flu is often confused with the common cold, but flu symptoms are usually more severe than the typical sneezing and stuffiness of a cold.

Symptoms of the flu may include:

• fever
• chills
• headache
• muscle aches
• dizziness
• loss of appetite
• tiredness
• cough
• sore throat
• runny nose
• nausea or vomiting
• weakness
• ear pain
• diarrhea

Infants with the flu may simply seem sick all of a sudden or "just don't look right." The flu discussed here is not the same strain of virus as the avian flu.

Duration

After 5 days, fever and other symptoms have usually disappeared, but a cough and weakness may continue. All symptoms are usually gone within a week or two. However, it's important to treat the flu seriously because it can lead to pneumonia and other life-threatening complications, particularly in infants, senior citizens, and people with long-term health problems.

Contagiousness

Spread by virus-infected droplets that are coughed or sneezed into the air, the flu is contagious. People infected with the flu are contagious from a day before they feel sick until their symptoms have resolved (usually about 1 week for adults, but can be up to 2 weeks for young kids).

The flu usually occurs in small outbreaks, but epidemics tend to occur every several years. Epidemics (when the illness spreads rapidly and affects many people in an area at the same time) peak within 2 or 3 weeks after the first cases occur

About the Flu Vaccine

The flu Larissa Hirsch, MD
Date reviewed: October 2007

Influenza (Flu)

Influenza, commonly known as "the flu," is a highly contagious viral infection of the respiratory tract. Although the flu affects both sexes and all age groups, kids tend to get it more often than adults. The illness even has its own season — from November to April, with most cases occurring between late December and early March.

Signs and Symptoms

The flu is often confused with the common cold, but flu symptoms are usually more severe than the typical sneezing and stuffiness of a cold.

Symptoms of the flu may include:

• fever
• chills
• headache
• muscle aches
• dizziness
• loss of appetite
• tiredness
• cough
• sore throat
• runny nose
• nausea or vomiting
• weakness
• ear pain
• diarrhea

Infants with the flu may simply seem sick all of a sudden or "just don't look right." The flu discussed here is not the same strain of virus as the avian flu.

Duration

After 5 days, fever and other symptoms have usually disappeared, but a cough and weakness may continue. All symptoms are usually gone within a week or two. However, it's important to treat the flu seriously because it can lead to pneumonia and other life-threatening complications, particularly in infants, senior citizens, and people with long-term health problems.

Contagiousness

Spread by virus-infected droplets that are coughed or sneezed into the air, the flu is contagious. People infected with the flu are contagious from a day before they feel sick until their symptoms have resolved (usually about 1 week for adults, but can be up to 2 weeks for young kids).

The flu usually occurs in small outbreaks, but epidemics tend to occur every several years. Epidemics (when the illness spreads rapidly and affects many people in an area at the same time) peak within 2 or 3 weeks after the first cases occur

About the Flu Vaccine

The flu Larissa Hirsch, MD
Date reviewed: October 2007

Influenza (Flu)

Influenza, commonly known as "the flu," is a highly contagious viral infection of the respiratory tract. Although the flu affects both sexes and all age groups, kids tend to get it more often than adults. The illness even has its own season — from November to April, with most cases occurring between late December and early March.

Signs and Symptoms

The flu is often confused with the common cold, but flu symptoms are usually more severe than the typical sneezing and stuffiness of a cold.

Symptoms of the flu may include:

• fever
• chills
• headache
• muscle aches
• dizziness
• loss of appetite
• tiredness
• cough
• sore throat
• runny nose
• nausea or vomiting
• weakness
• ear pain
• diarrhea

Infants with the flu may simply seem sick all of a sudden or "just don't look right." The flu discussed here is not the same strain of virus as the avian flu.

Duration

After 5 days, fever and other symptoms have usually disappeared, but a cough and weakness may continue. All symptoms are usually gone within a week or two. However, it's important to treat the flu seriously because it can lead to pneumonia and other life-threatening complications, particularly in infants, senior citizens, and people with long-term health problems.

Contagiousness

Spread by virus-infected droplets that are coughed or sneezed into the air, the flu is contagious. People infected with the flu are contagious from a day before they feel sick until their symptoms have resolved (usually about 1 week for adults, but can be up to 2 weeks for young kids).

The flu usually occurs in small outbreaks, but epidemics tend to occur every several years. Epidemics (when the illness spreads rapidly and affects many people in an area at the same time) peak within 2 or 3 weeks after the first cases occur

About the Flu Vaccine

The flu Larissa Hirsch, MD
Date reviewed: October 2007

Influenza (Flu)

Influenza, commonly known as "the flu," is a highly contagious viral infection of the respiratory tract. Although the flu affects both sexes and all age groups, kids tend to get it more often than adults. The illness even has its own season — from November to April, with most cases occurring between late December and early March.

Signs and Symptoms

The flu is often confused with the common cold, but flu symptoms are usually more severe than the typical sneezing and stuffiness of a cold.

Symptoms of the flu may include:

• fever
• chills
• headache
• muscle aches
• dizziness
• loss of appetite
• tiredness
• cough
• sore throat
• runny nose
• nausea or vomiting
• weakness
• ear pain
• diarrhea

Infants with the flu may simply seem sick all of a sudden or "just don't look right." The flu discussed here is not the same strain of virus as the avian flu.

Duration

After 5 days, fever and other symptoms have usually disappeared, but a cough and weakness may continue. All symptoms are usually gone within a week or two. However, it's important to treat the flu seriously because it can lead to pneumonia and other life-threatening complications, particularly in infants, senior citizens, and people with long-term health problems.

Contagiousness

Spread by virus-infected droplets that are coughed or sneezed into the air, the flu is contagious. People infected with the flu are contagious from a day before they feel sick until their symptoms have resolved (usually about 1 week for adults, but can be up to 2 weeks for young kids).

The flu usually occurs in small outbreaks, but epidemics tend to occur every several years. Epidemics (when the illness spreads rapidly and affects many people in an area at the same time) peak within 2 or 3 weeks after the first cases occur

About the Flu Vaccine

The flu Larissa Hirsch, MD
Date reviewed: October 2007

Influenza (Flu)

Influenza, commonly known as "the flu," is a highly contagious viral infection of the respiratory tract. Although the flu affects both sexes and all age groups, kids tend to get it more often than adults. The illness even has its own season — from November to April, with most cases occurring between late December and early March.

Signs and Symptoms

The flu is often confused with the common cold, but flu symptoms are usually more severe than the typical sneezing and stuffiness of a cold.

Symptoms of the flu may include:

• fever
• chills
• headache
• muscle aches
• dizziness
• loss of appetite
• tiredness
• cough
• sore throat
• runny nose
• nausea or vomiting
• weakness
• ear pain
• diarrhea

Infants with the flu may simply seem sick all of a sudden or "just don't look right." The flu discussed here is not the same strain of virus as the avian flu.

Duration

After 5 days, fever and other symptoms have usually disappeared, but a cough and weakness may continue. All symptoms are usually gone within a week or two. However, it's important to treat the flu seriously because it can lead to pneumonia and other life-threatening complications, particularly in infants, senior citizens, and people with long-term health problems.

Contagiousness

Spread by virus-infected droplets that are coughed or sneezed into the air, the flu is contagious. People infected with the flu are contagious from a day before they feel sick until their symptoms have resolved (usually about 1 week for adults, but can be up to 2 weeks for young kids).

The flu usually occurs in small outbreaks, but epidemics tend to occur every several years. Epidemics (when the illness spreads rapidly and affects many people in an area at the same time) peak within 2 or 3 weeks after the first cases occur

About the Flu Vaccine

The flu Larissa Hirsch, MD
Date reviewed: October 2007