The flu is a viral respiratory infection. It’s similar to the common cold but more severe, with both upper respiratory (nose/throat) and lower respiratory (lung) symptoms, along with general symptoms like fever, chills, aches, lethargy, nausea/vomiting, stomach aches, etc. This page will discuss what causes it, how to manage it, and when to make an appointment or seek urgent medical attention.
What causes it? The flu is caused by one of several different strains of the influenza virus. The strains change year to year, with usually a couple strains that predominate on any given year. Influenza viruses infect about 15-20% of the population each year. This means that most years you won’t catch the flu; on average you should get it once every 5-6 years. There are also many other viruses that cause “flu-like” illnesses, meaning they give you all the symptoms of the flu but they’re not the actual influenza virus.
Every decade or so there is a pandemic strain of influenza that circulates the globe (such as H1N1 in 2009/2010). During these times many more people catch the flu than in typical seasons because our immune systems have no experience with the new strain. Because we are naturally less protected, complication rates tend to be higher.
What causes flu symptoms? As with the common cold, most of the actual symptoms are not caused by the virus itself, but by your body’s attempt to fight the virus. This is an important point because it impacts how we treat the infection. The difference with the flu and the common cold, though, is that the flu virus infects the body more strongly than common colds do, causing both a stronger immune response as well as more bodily harm. This means that we need to monitor the flu more closely, and make sure that your child is tolerating the infection well.
Natural course of the flu. The flu usually has a pretty abrupt onset of fever and cough, accompanied soon by chills, aches, nausea, stomach aches, and low energy. This “acute phase” of the virus usually lasts just 3-5 days, after which point the fever breaks and it may be followed by several days to even weeks of drawn-out mild symptoms, such as nasal drainage, cough, and low energy.
How to treat the flu. The flu generally resolves on its own in most children, but children less than 2 years of age and those with certain medical conditions may need antiviral medications and often require close monitoring (see below). The mainstay of therapy revolves around keeping your child hydrated, and treating the symptoms of the illness to keep your child comfortable. The details of this can be found throughout my website (see the common cold, fever, and hydration/vomiting pages).
When is prescription medication indicated? Unlike with the common cold, we actually do have antiviral medications available for influenza. These medications do have side effects and aren’t 100% effective, so they are often not used for routine cases of the flu in healthy young adults and older children. They are indicated for children less than two years of age, children with pre-existing medical conditions (see below), and severe cases. In order to be effective, the medications need to be started within the first two days of illness, so if your child falls into one of these groups you’ll want to seek medical attention as early as possible.
Some conditions put children at increased risk for influenza-related complications. If your child has any of the following conditions, they should receive antiviral medication on contracting influenza, and should be monitored closely:
- asthma or other lung problems
- heart conditions
- weakened immune systems
- severe prematurity
- neurologic/neuromuscular conditions
- moderate to severe developmental delay
- significant metabolic or endocrine disorders
- disorders of the blood or kidneys
Complications of the flu are relatively common, and include ear infections, sinus infections, and pneumonia to name a few. Such complications are often treated with antibiotics. Children who are unable to breathe well or remain hydrated on their own may need to go into the hospital to receive oxygen, fluids, and medication.
While this may all sound frightening to you, remember that influenza is common, the vast majority of cases in children resolve on their own, and with diligent supportive care we are able to prevent lasting complications in most children. So watch your child closely, provide a lot of vitamin L (love), maintain good hydration, and contact our office if you need any help.
Monitoring your child.
If your child presents with a relatively rapid onset of fever, cough, and body aches in the middle of flu season, chances are they caught the flu. Most cases can be safely monitored at home, but we are always happy to evaluate your child in the office whenever you would like confirmation or are unsure what's going on. Use the following as a rough guide for when you need to call urgently or bring your child in to be seen by us:
Call for an appointment right away if:
- Child less than 2 years of age.
- High-risk child/pre-existing medical condition (see above for details).
- “Acute phase” (fever + heavy cough) lasting more than 3-4 days or particularly severe.
- Lingering milder symptoms after acute phase that take more than a week to resolve.
- Severe or progressive symptoms. (Usually the flu is full-blown by day 1-3 of illness, then starts to resolve several days later. If you note symptoms that instead get progressively more severe day by day, this may indicate a developing complication.)
- Not in acute distress, but respirations are becoming a bit labored.
- Difficulty staying hydrated.
Call urgently or go into ER if:
For urgent needs, same-day appointments are available Monday through Friday. Please call as early in the day as possible, the more notice we have the easier it is to fit everyone in.
Need help outside of office hours?
Firstly, if your child has an emergency, please call 911 or go directly to the ER - they will contact us if needed once your child has been evaluated.
Urgent Care centers can also be helpful when something needs to be seen outside of office hours but it's not an emergency.
For our list of preferred Urgent Cares and ERs, see our resources page.
And if you have something that might need urgent attention but you're not sure/don't know what to do, we can help: