Flu Overview: Symptoms, Treatment, Prevention, and How to Avoid Dehydration

Flu Signs & Symptoms

Many people get the flu every year, and everyone can consequently become dehydrated. The flu (short for “influenza”) is a common viral infection. You can recognize signs of the flu when feeling stuffed up, dizzy, lethargic, and hot/cold all at the same time. To determine the difference between common cold and flu, pay attention to symptoms like fever and physical aches which make self-diagnosing easier. Other signs and symptoms of the influenza virus may include:

  • Sore throat
  • Runny and/or stuffy nose
  • Intermittent or incessant coughing
  • Headache
  • Muscle and/or joint aches
  • Weakness and fatigue
  • Dehydration

Additionally, children with the flu may experience:

*Seek immediate medical help if your child is suffering from severe diarrhea or vomiting.

Flu Treatment & Prevention


If you already have the flu, take the following measures to accelerate recovery:

  • Stay hydrated by drinking plenty of fluids (explained below)
  • Get plenty of rest and sleep
  • Avoid physically taxing activities
  • Put a cool, damp cloth on your forehead to reduce fever
  • Use cough suppressants to treat cough

If symptoms persist and/or worsen, you may want to take OTCs and/or antiviral medication such as:

  • Tylenol or Advil: the umbrella drug that treats most common illnesses, including flu and fever.
  • Tamiflu or Relenza: these antiviral medications are used to treat/prevent the flu and shorten illness time. They’re most effective when taken within 48 hours of getting the flu. Tamiflu is taken orally, while Relenza is taken through an inhaler. Both of these require a prescription from your doctor.

*Be sure to seek medical clearance from your doctor before taking any medication.

Prevention before and during flu season

The best way to be flu-free during flu season (October to May with a peak in February) is to get a vaccination, or the “flu shot.” Most health insurance plans include free flu shots and many pharmacies or local clinics can give flu shots quickly and easily.

It’s also always recommended you follow basic hygiene practices like washing/soaping your hands regularly and avoiding physical contact with infected people.

Flu and Dehydration

Having the flu also puts you at increased risk of dehydration. Dehydration occurs when your body loses more water than it takes in. The importance of water to our health and bodies goes without saying, so to be at an imbalance is no small issue.

But first, what exactly is the correlation between having the flu and dehydration?

The science of flu and dehydration

The flu often brings about a change in body temperature (e.g. fever), which typically leads to an increased metabolism (i.e. the sum total chemical reactions in your body’s cells). A fever of 101 degrees Fahrenheit (F) means a metabolic rate spike of ~10%.

Why is that important? An increased metabolism means two things:

  1. Your body expels i.e. loses more water.
  2. You breathe faster, thereby releasing more moisture.

In combination, losing too much water and moisture together can create an imbalance in your body, ultimately leading to dehydration. Additionally, signs and symptoms of different flu strains, like vomiting and diarrhea, can lead to a rapid loss of fluids and electrolytes as well.

The flu and dehydration in children

Like most illnesses and ailments, the flu affects children more severely than it does adults. In turn, children are also more likely to suffer from dehydration. This is due to a number of reasons:

  • Children have higher metabolisms than adults, which means they use and expel more water.
  • Their bodies aren’t strong enough or fully developed to fight infections, which increases the likelihood and/or frequency of diarrhea and vomiting.
  • Their kidneys don’t process fluid as well as an adult.
  • Their bodies are made up of more water than adults’ (a baby is ~75% water, while an adult is only ~60%).

Whether it’s you or your child, it’s important to take measures to stay hydrated while fighting the flu.

Read more about managing dehydration in children

Did You Know?

Kids are more likely to experience vomiting & diarrhea during the flu than adults.

Best (and worst) fluids to drink when you have the flu

With an increased metabolic rate from the flu, the loss of water can create an imbalance in your body, leading to dehydration. To restore balance and stay hydrated, it’s important to drink plenty of fluids.

But not every drink is created equal; while some liquids help, others won’t keep you hydrated very well. It’s important to be able to understand which is which, so you know exactly what to ingest.

What to Drink When You Have the Flu

  • Water: When in doubt, drink water. As mentioned above, our bodies are mostly water and due to higher metabolic rate during the flu we lose lots of water in the chemical reaction process. Water keeps you hydrated while combating stuffiness and congestion.
    • Too much water? Make sure, however, that you don’t overdo it, as there is such a thing as excessive water consumption. Too much water can dilute your blood, thereby offsetting your body’s electrolyte balance. In extreme cases, drinking too much water could lead to hyponatremia, when sodium levels plummet, possibly resulting in brain swelling and potential coma or death.
  • Lemons: Though not technically a drink, lemons are great enhancers to other helpful drinks on this list because of their vitamin/nutrient-filled properties. Your immune system takes a hit when you have the flu, but the high vitamin C content in lemons helps boost your immune system back up. Lemons also contain antibacterial and antiviral properties like calcium, citric acid, magnesium, bioflavonoids, and pectin, all which help fight infection.
  • Decaf tea: Heat is a great soother to many flu symptoms including sore throat, sinus congestion, and upset stomach. Herbal teas also help relax the body (and mind) while boosting your immune system. Adding honey can also help soothe coughing during a flu.
  • Soup or veggie broths : As with tea, hot soup is an excellent soother/healer, and the heat is also good for breaking up mucus. During a flu, you may not have much of an appetite; soup is a great way to get proteins and minerals without having to eat too much. While soup may be high in sodium, when you have the flu you risk losing not just water but essential sodium as well. Eating soup can help replenish both.
  • Electrolyte solution drinks: Electrolyte solution drinks (or oral rehydration solutions) promote a proper balance between water, glucose, and sodium. They typically contain less sugar than sports drinks, making them an overall healthier option. Hydralyte electrolyte solution drinks are designed to rapidly replace fluids and electrolytes in your body to relieve dehydration caused by vomiting, diarrhea, fever, or heavy sweating.

Drinks that exacerbate dehydration

Sugary drinks: Sugar in high amounts can suppress the immune system and cause inflammation, which can stimulate nerves and cause pain.

Caffeinated drinks: To drink or not to drink coffee when you’re sick? Widely debated, while some say caffeine isn’t so bad, there’s a host of other studies claiming otherwise. While the jury may still be at an impasse, what can be said is this: there are plenty of other liquids that help fight the flu and dehydration better than caffeinated drinks.

Alcohol: Alcohol promotes diuresis, which increases urine production and naturally dehydrates the body. Drinking alcohol with the flu will most likely exacerbate present symptoms, including headache, body ache, and nausea.

Ultimately, when you have the flu, make sure to get plenty of rest and stay hydrated. Hydralyte electrolyte solution drinks can help rapidly rehydrate your body just when you need it most and relieve the dehydration caused by symptoms of the flu.

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