This post gives an elaborate explanation of the flu symptoms and the early warning signs that can warn you that you have been infected with influenza or the flu virus.

It tells you of those symptoms that manifest in adults, children, and infants of the impending flu fever. This becomes especially significant in children and infants who are unable to express what they feel, making diagnosis difficult because variations in symptoms do occur. For example, you can have influenza or the flu even without symptoms such as no fever, cough, or body ache.

You could have a cold as a symptom. In such a case how do you differentiate the common cold from the flu infection?

This post also tells you how soon you can develop those first symptoms after you have been exposed to the influenza virus, during which months the influenza virus is most active, and how long the symptoms last.

The influenza symptoms can be severe or mild. They can last for weeks or may disappear within one week.

The duration and severity of the flu illness symptoms depend on two things:

  1. Your overall health, which is governed by your nutrition, lifestyle habits, and any other risk factors that make you more prone to catching the flu.
  2. The virulence of the flu virus means how strong and dominant, the virus is.

Flu Symptoms

Following are the common symptoms of flu that may be seen in the patient. Not all symptoms may be present, but you could have any one or more of these.

  • High fever with rigors – meaning high fever accompanied by shivering due to feeling very cold. In children, below 5 years and in people over 65 years, fever may not be seen. Fever usually lasts for 3 to 5 days and the patient feels better after that. Fever is found in about 70% of flu patients.
  • A running or a blocked nose. A running nose is more common in children. The mucus can turn yellow indicating that bacterial infection has set in. The doctor may then prescribe antibiotics as well.
  • Headache
  • Red, watery and painful eyes
  • A sore throat causing pain
  • Dry cough
  • Generalized bodyache more so in the back and legs
  • Pain in the muscles and joints
  • A feeling of fatigue
  • Loss of appetite
  • Not wanting to drink fluids
  • Dark-colored urine due to low intake of fluids or water
  • An upset stomach leads to nausea, persistent vomiting, and diarrhea. You will see these symptoms more in children.
  • Sudden bouts of dizziness
  • Red or purple colored spots may develop on the skin, especially on the lips, which are due to minor hemorrhages from broken blood capillaries under the skin.
  • Seizures are due to high fever, which accompanies the flu illness. They are, therefore,  called febrile seizures and are seen more commonly in children. Temperatures of 102 degrees Fahrenheit and higher can cause such febrile seizures.
  • In babies, diagnosis is difficult but usually excessive crying can be the first clue in the differential diagnosis of influenza.

Early recognition of the flu symptoms will help in taking treatment early. This reduces the severity and duration of the illness.

Early warning signs and symptoms of flu

In infants

  • Being unable to eat
  • Has trouble breathing
  • Has no tears when crying.
  • Significantly fewer wet diapers than normal due to decreased intake of water.

In children

  • The skin acquires a bluish tinge
  • Fever with skin rash
  • Not wanting to eat or drink anything
  • Fewer wet diapers due to low intake of water
  • Fast and troubled breathing
  • Being so irritable that the child does not want to be held
  • Excessive crying
  • Not waking up easily and not interacting

In adults

  • Fast breathing that requires extra effort
  • Pain or pressure in the chest or abdomen
  • Irritability
  • Not being able to concentrate leading to confusion
  • Severe and frequent vomiting
  • Fever may go and return

How soon can you get the flu symptoms after being exposed to the virus?

After you have been exposed to the flu virus, you can fall sick and the symptoms can appear quickly within one to four days. Usually, it is for two days. This is called the incubation period of influenza or flu disease.

The symptoms come on suddenly like out of nowhere. You feel like being suddenly hit by something. You could be fine one moment and within an hour or so, you could be down and miserable with the symptoms. That is why some people tend to call flu the “overnight sickness”.

These symptoms should be taken seriously, especially in children, as complications can occur, which can be serious.

How long do flu symptoms last? 

A bout of flu with no complications can last for one to two weeks. The symptoms peak in just two to three days and the severe symptoms can subside as suddenly as they had come after that.

However, weakness, fatigue, a dry cough, and a low appetite can still bother you for a few days or weeks more, depending on the severity of the illness.

According to the Centers for Disease Control and Prevention (CDC), you can resume your duty 24 hours after your fever has subsided. Till then you should refrain from attending work or school.

If you develop complications, things become different and the duration of the illness will depend on the complication that has set in.

Symptoms that can last longer

Even if you are a healthy individual with no flu complications, you may still be daunted with some mild symptoms that can linger for weeks. They include:

  • Fatigue due to weakness
  • Low appetite
  • Dry cough
  • Irritation in the throat
  • Loss of sense of smell and taste, which returns within two to three days but in rare cases, can last for months

The way to get rid of these symptoms as quickly as possible is to take adequate rest, drink plenty of fluids, persist with your medication if any, and keep physical activity at a minimal level.

Asymptomatic flu 

Not all patients with influenza or flu have the symptoms. One in three influenza-infected individuals is asymptomatic. You could have the flu, but no fever or cold, or weakness. About 33% of patients do not present any symptoms. And those that do, present the symptoms 1 to 4 days after getting infected.

The patient can pass on the virus a day before he or she develops the symptoms and for up to a week after the symptoms have developed. Even the patients without symptoms can pass on the virus and infect others.

Why your flu symptoms may not improve?

At times, some people may experience flu symptoms that don’t go away. They just do not improve.

Flu is a viral disease and, therefore, self-limiting — meaning it should go away even without medication.

Your doctor gives you medication to manage your symptoms so that you suffer less. The virus runs its course and as mentioned above, some mild symptoms persist for weeks

But, if your symptoms persist and do not go away, it means there is something else your doctor will consider.

You may not be taking adequate rest and nutrition and fluids or you may have developed certain complications, which require further treatment.

Taking adequate rest will help your body to rejuvenate and will prevent you from causing and spreading the flu infection to others

When should you see the doctor?

You should see the doctor under the following conditions:

  • The presence of fever in an infant, even if the fever is mild as in 100 degrees F.
  • The presence of high fever in a child of up to 5 years. High fever is a fever above 100 degrees Fahrenheit.
  • The presence of fast breathing and difficulty in breathing in a child or adult
  • Fever persists even after five days in a child or adult
  • A child with a fever who refuses to eat and drink fluids
  • If signs of dehydration set in such as no passing of urine
  • You have a fever that goes away and then returns. This could be a sign of bacterial infection requiring further treatment.
  • The presence of fever in an adult or child accompanied by a severe headache or stiff neck, confusion, and difficulty in waking up.