Influenza (Flu)

Overview

The flu, or influenza, is a respiratory infection caused by influenza viruses that target the nose, throat, and lungs. This virus differs from the so-called “stomach flu,” which causes gastrointestinal symptoms like vomiting and diarrhea. While most people recover from the flu on their own, complications can sometimes make it a serious or even life-threatening condition, particularly for individuals at higher risk, such as older adults and young children.

To reduce the risk of severe flu complications, an annual flu shot is recommended. Although not entirely foolproof, the flu vaccine significantly lowers the chance of experiencing severe illness from influenza. In addition to vaccination, preventive measures like disinfecting surfaces, practicing good hand hygiene, and maintaining good airflow can help decrease the risk of contracting and spreading the flu.

What Causes The Flu?

The flu, or influenza, is caused primarily by various strains of the influenza virus, which can spread easily and widely. In addition to the viral infection itself, environmental and individual health factors play important roles in influencing the spread and severity of flu outbreaks. Here are the main causes of the flu:

Viral Infection

The primary cause of the flu is the influenza virus, which spreads through respiratory droplets when an infected person coughs, sneezes, or talks. Common symptoms include a runny or stuffy nose, which can contribute to the spread of the virus. These droplets can be inhaled by individuals nearby, leading to infection. The symptoms of flu A and B are more severe and are seasonal, with the majority of cases occurring in the winter, commonly referred to as the seasonal flu.

Environmental Factors

Cold weather and low humidity levels create an environment conducive to the survival of the flu virus. During fall and winter, people tend to spend more time indoors, increasing the likelihood of transmission. Flu seasons typically occur from October to May, with peak activity in the winter months.

Weakened Immune System

Individuals with compromised immune systems—such as the elderly, young children, and those with chronic health conditions—are more susceptible to flu infections due to their body’s reduced ability to fend off viruses.

What Are the Types of Flu?

There are four main types of influenza viruses: Influenza A, B, C, and D, each with distinct characteristics and impacts on human and animal health. Here’s a look at each type:

Influenza A

One of the most prevalent and possibly dangerous forms of the flu is influenza A. This particular influenza virus can spread swiftly and change into several subtypes because it infects both people and animals, including pigs and birds. Large-scale seasonal flu outbreaks and sporadic pandemics are frequently caused by influenza A viruses, which can cause mild to severe symptoms.

Influenza B

Another prevalent flu that mostly affects people is influenza B, which is especially harmful to young people. Influenza B does not cause pandemics and does not infect animals like Influenza A does. Seasonal flu outbreaks can still result from it, though, particularly in the winter months. Similar to influenza A, but usually less severe, are the symptoms..

Influenza C

Influenza C is less prevalent and mostly affects children, causing minor respiratory illnesses. This kind usually causes mild symptoms that are similar to a cold and lacks the seasonal fluctuation found in Influenza A and B. Influenza C outbreaks occur less frequently and are not linked to widespread epidemics.

Influenza D

There is no evidence that influenza D can infect people; it mostly affects animals. Generally speaking, this form of influenza is thought to have less of an influence on public health than other forms and has received less research. Even while it doesn’t directly endanger people, it can have an impact on the health of cattle and may have ramifications for animal agriculture.

How Does the Flu Spread?

Contact with an infected person, whether direct or indirect, can spread the influenza virus. Here are some common ways to contract the flu:

• From a cough, sneeze, or conversation coming from someone close by. Either droplets can land on your hands or they can go through the air and land in your mouth or nose. Your lungs are then affected by the flu.

• By coming into contact with an infected surface and then touching your eyes, mouth, nose, or face. This covers items such as desks, phones, computers, and door knobs.

• By contacting a person who has the flu and then touching your face, nose, mouth, or eyes.

What Are the Symptoms of the Flu?

Flu symptoms can come on quickly and often leave you feeling exhausted. Here’s a closer look at each common symptom and why it appears:

Sudden Onset of Fever

A fever is your body’s natural response to fighting off the flu virus. When the immune system detects the virus, it raises your body temperature to make the environment less hospitable for the virus, helping to slow its spread.

Chills

Chills often accompany fever as your body tries to reach its higher temperature set point. These shaking or shivering sensations are caused by muscle contractions, which help generate heat to warm the body as it fights the infection.

Body Aches

Body aches are a common flu symptom due to your immune system’s response to the infection. Chemicals released to combat the virus can cause inflammation in muscles and joints, leading to widespread soreness and discomfort.

Fatigue

The body requires energy to fight off infections, so you may feel extremely tired or weak during the flu. Fatigue is also your body’s way of encouraging rest so it can focus on healing and recovery.

Sore Throat

A sore throat often results from inflammation caused by the flu virus in the respiratory tract. This inflammation can make swallowing painful and irritating, and it’s common as the body’s immune response kicks in.

Headache

Headaches can occur due to a combination of factors, including dehydration, congestion, and the release of inflammatory chemicals as the body fights off the flu. The increased pressure in the sinuses can also contribute to the pain.

Cough

A cough helps clear the respiratory passages of mucus and viral particles. While it can be uncomfortable, coughing is the body’s way of clearing the airways, which are often irritated by the flu virus.

Vomiting or Diarrhea (in children)

Children with the flu may experience vomiting or diarrhea as the virus affects their digestive system. This is more common in children than in adults and can lead to dehydration if fluids aren’t replaced.

How Do You Diagnose the Flu?

To diagnose the flu your healthcare professional does a physical exam, looks for symptoms of flu and possibly orders a test that detects flu viruses. 

Rapid Influenza Diagnostic Tests (RIDT)

RIDTs are simple tests that detect influenza viral antigens in respiratory specimens. The process typically involves swabbing the nose or throat and obtaining results within 15-30 minutes. While quick, these tests may not always provide accurate results.

PCR Tests

Polymerase chain reaction (PCR) tests are more sensitive and specific for diagnosing influenza. This test amplifies viral genetic material in a sample, providing results within a few hours to a day. PCR tests are particularly useful during peak flu season when accurate diagnosis is crucial. 

What Are the Stages of Flu Recovery?

Incubation (1-4 Days After Exposure)

The incubation period for the flu lasts about 1-4 days after exposure. During this time, the symptoms may not yet be noticeable, but the virus is actively replicating. Individuals may start to feel slightly fatigued or have a minor sore throat, but symptoms haven’t fully set in. 

Sudden Onset of Symptoms

The flu  can begin unexpectedly with symptoms that seem to come on unexpectedly. The initial symptoms include fever, chills, headaches, and body aches, along with coughing and sore throat. The body’s immune reaction to fight the virus starts with these early symptoms, which can be severe. 

Peak Symptoms (Days 2-3)

Days 2-3 are typically the most severe, with symptoms reaching their peak intensity. This period can last several days, and individuals often experience extreme fatigue and significant discomfort. Cough and sore throat can also be more intense. This is the phase where your immune system is fully engaged in fighting off the virus, resulting in heightened symptoms.

Recovery (Days 4-7) 

The symptoms gradually begin to go away by day four. The fever frequently goes down, and the severity of the chills, body aches, and exhaustion starts to lessen. Rest and hydration are crucial during this time since the body is still trying to eradicate the virus entirely. Mild weariness and a persistent cough may continue even after symptoms are improving. Seasonal flu tends to have worse outcomes for young children, particularly those under 2 years old, as well as for older adults aged 65 and above.

Post-Recovery  (Lingering Cough or Fatigue)

Some aftereffects, such as a slight cough or persistent exhaustion, may persist for a few weeks after the major symptoms have subsided. As the body fully recovers lung function and immunological balance, these post-recovery symptoms are a natural part of the healing process. 

How Long Does the Flu Last?

The flu generally lasts about one to two weeks. However, symptoms can be more severe in the first few days and gradually improve as the immune system combats the virus. Some individuals may continue to feel fatigued or have a lingering cough for several weeks. The duration of the flu is mostly determined by an individual’s general health and immune system strength. A longer illness may be experienced by those with compromised immune systems, such as elderly people or those suffering from long-term medical issues.

How Long After Exposure Do Flu Symptoms Appear?

Flu symptoms typically appear about 1 to 4 days after exposure to the virus. This period can vary depending on the individual’s immune response and the specific strain of the virus.

Can You Get the Flu Twice in One Season?

Yes, it is possible to get the flu more than once in a single season. This can occur if an individual is exposed to a different strain of the virus that their immune system has not yet encountered.

What Is Flu Season, and When Does It Occur?

Flu season usually occurs in the fall and winter months, peaking during colder weather. This season can vary, but flu activity often increases in October and can last until May, with the highest levels typically seen from December to February.

What Groups Are at Higher Risk for Severe Flu Complications?

Young Children

Children under five, especially those under two years old, are at higher risk due to their developing immune systems.

The Elderly

Individuals aged 65 and older often have weakened immune systems, making them more susceptible to severe complications.

Pregnant Women

Pregnant women experience changes in their immune system, increasing their risk of severe illness and complications from the flu.

People with Chronic Conditions

Individuals with chronic conditions like asthma, diabetes, or heart disease are at higher risk for flu complications due to their compromised health.

What Are the Possible Complications of the Flu?

Pneumonia

The flu can lead to pneumonia, a serious lung infection that can be life-threatening, especially in high-risk groups.

Bronchitis

Inflammation of the bronchial tubes can occur, leading to bronchitis, which can cause persistent coughing and difficulty breathing.

Sinus Infections

The flu can cause inflammation in the sinuses, potentially leading to bacterial sinus infections that may require antibiotics.

Worsening of Chronic Conditions

Individuals with chronic health issues may experience exacerbated symptoms, leading to serious complications if not managed properly.

How Effective Are Antiviral Medications for the Flu?

 Antiviral drugs such as Tamiflu can shorten the duration and intensity when taken within 48 hours of the start of flu symptoms. They reduce the recovery period by one to two days, particularly for high-risk individuals, by preventing viral multiplication. These remedies, however, cannot take the place of the flu vaccine, which provides more comprehensive protection. For proper use, it’s crucial to speak with medical professionals, particularly for people who are more likely to experience difficulties.

What’s the Difference Between the Flu and a Cold?

While both the flu and the common cold are respiratory illnesses, they are caused by different viruses and have distinct symptoms. The flu typically presents with a sudden onset of high fever, body aches, and extreme fatigue, while a cold usually develops gradually and involves milder symptoms like a runny nose and sore throat.

How Is the Flu Different from COVID-19?

Despite being respiratory diseases brought on by distinct viruses, the flu and COVID-19 differ in several important ways:

1. Loss of Taste and Smell

The possible loss of taste and smell is one of the most notable characteristics that sets COVID-19 apart. The flu is not frequently linked to this symptom. This can happen anywhere from two days after catching the virus to fourteen days after symptoms start, while not all patients will experience it (between 38 and 55 percent report losing their taste, and about 40 percent report losing their scent). It can be crucial to identify this symptom in order to distinguish between the two conditions.

2. Duration and Severity of Symptoms

Coughing and dyspnea are common symptoms of both diseases, but COVID-19 symptoms can be more severe and stay longer. According to Dr. Wong, shortness of breath may appear later and frequently worsen than in flu instances, and COVID-19 symptoms can last for several weeks or even months.

Is the Stomach Flu the Same as Influenza?

No, the “stomach flu” is not the same as influenza. The term typically refers to viral gastroenteritis, which affects the stomach and intestines, causing diarrhea and vomiting, unlike influenza, which primarily affects the respiratory system.

How Can I Prevent the Flu?

Get Vaccinated

Annual flu vaccinations are recommended to protect against the most common strains of the virus. Flu vaccination is crucial for reducing the spread of the virus and protecting vulnerable populations. The nasal spray flu vaccine is an option for individuals aged 2 to 49 and offers an alternative to the traditional flu shot. The vaccine is updated each year to ensure effectiveness. Flu vaccines are available in various forms, including shots and nasal sprays, to accommodate different age groups and medical conditions.

Wash Hands Frequently

Washing hands regularly with soap and water for at least 20 seconds helps prevent the spread of germs. Hand sanitizer can also be used when soap and water are unavailable.

Avoid Close Contact with Sick Individuals

Keeping a safe distance from those who are ill can reduce your risk of contracting the virus.

Cover Your Coughs and Sneezes

Using a tissue or the inside of your elbow to cover your mouth and nose when coughing or sneezing helps prevent the spread of respiratory droplets.

Can I Get the Flu Shot if I’m Sick?

Cases of the flu start to increase in winter time, making annual flu vaccination one of the most important means to prevent getting sick.

A person with a moderate sickness, like a cold or sinus infection, can still receive the flu vaccine. However, if someone is ill and should get the flu shot, they should consult a physician. People may occasionally need to wait until they are well before getting vaccinated.

A person can discuss their symptoms or concerns with a doctor if they are unsure about having the flu shot.

What Should I Do If I Get Sick?

Rest and Hydrate

Getting plenty of rest and staying hydrated can help your body recover more quickly.

Consult a Healthcare Provider

If symptoms are severe or if you belong to a high-risk group, seek medical advice promptly for possible antiviral treatment.

Monitor Symptoms

Keep track of your symptoms and watch for any complications, particularly if you have underlying health conditions.

What Foods Should I Avoid During the Flu?

When recovering from the flu, it’s important to avoid certain foods and drinks that can hinder your recovery:

Foods to Avoid

• Processed Foods: These are high in sugars and unhealthy fats, which can increase inflammation and weaken your immune system.

• Dairy Products: Dairy may thicken mucus for some, worsening congestion and sore throats.

• Spicy Foods: They can irritate your throat and exacerbate coughing.

Drinks to Avoid

• Sugary Drinks: Sodas and high-sugar juices can promote inflammation and hinder immune response.

• Caffeinated Beverages: These can lead to dehydration, counteracting the need for hydration during illness.

• Alcohol: It can dehydrate you and interfere with flu medications.

What Should I Avoid After Getting the Flu Shot?

Although there aren’t any exact guidelines following a flu shot, the following should be taken into account:

Strenuous Activity

If you have mild side effects, especially arm soreness, give your body 24 to 48 hours to recuperate.

Alcohol

Drinking alcohol might weaken your immune system and perhaps cause dehydration, which exacerbates any negative consequences.

Junk Food 

It’s always best to nourish your body with nutritious foods, particularly when your immune system is most in need of support.

Can You Get Rid of the Flu in 24 Hours?

The phases of flu recovery are pretty predictable, but each person’s experience with the flu (influenza) is slightly different. In most cases, symptoms appear rapidly and persist for three to seven days. Most recover in two weeks.

What Medicine Is Best for the Flu?

When treating the flu, several medications can help manage symptoms, but it is better to consult a primary care doctor for personalized advice. Common options include:

Antivirals

Medications like Oseltamivir (Tamiflu) can shorten flu duration if taken early.

OTC Medications

Pain relievers (e.g., acetaminophen, ibuprofen) help reduce fever and aches, while decongestants relieve nasal congestion.

Home Remedies

Staying hydrated with fluids like broth and herbal teas can support recovery.

What Should I Do If My Flu Symptoms Worsen?

You must get medical help right once if your flu symptoms get worse. Keep an eye out for symptoms like confusion, chest pain, or trouble breathing, as these could be signals of pneumonia or other serious problems. Additionally, you should see your doctor if you have a high fever that doesn’t go away or if your symptoms persist longer than expected.

What Are Some Common Flu Myths?

Myth 1: The flu shot can give you the flu.
Many think that the flu vaccine can cause illness, but this is false. The shot contains inactivated or weakened virus, which cannot cause the flu. Mild side effects, like soreness or low-grade fever, indicate the body is building immunity, not that you have the flu.

Myth 2: You don’t need to get vaccinated every year.
Some believe one vaccine lasts a lifetime, but flu viruses mutate frequently. Annual vaccination is essential to protect against new strains, as the vaccine is updated yearly to match circulating viruses.

What Are the Side Effects of the Flu Vaccine?

The majority of the flu vaccine’s adverse effects are minor, and it is generally safe. Typical side effects include muscle aches, low-grade fever, and injection site soreness. These often disappear in a few days as your body develops immunity. Since there are rarely any serious adverse effects, vaccination is an essential part of avoiding the flu. 

Conclusion

It’s important to comprehend the flu’s causes, symptoms, and preventative actions in order to manage it properly. You can greatly reduce your risk of catching the virus by being vaccinated annually, practicing excellent hygiene, and getting medical help as soon as possible. It’s critical to put your health first if you start to feel like you have the flu. Rest and see a doctor if necessary.

For additional guidance on flu management and preventive care, resources like Manhattan Medical Arts provide valuable information to help you navigate this seasonal illness effectively. Stay informed and take the necessary precautions to protect yourself and your community.

Disclaimer

This information is intended for educational purposes only and should not be considered a substitute for professional medical advice. If you have concerns about influenza or any other medical condition, please see a doctor for an accurate diagnosis and personalized treatment suggestions.