What you need to know about the Flu.

What is the flu?

The flu is caused by the influenza virus (so please don’t ask for an antibiotic). There are 3 different influenza viruses that cause illness in humans, Influenza A, B, and C. Unless you are a cow reading this you probably won’t care about Influenza D. Influenza A and B are responsible for seasonal outbreaks. Of the 2 (flu A and B), think of A as the slightly worse and more common type. Flu A has the ability to cause pandemics, whereas flu B cannot. Flu C typically causes less severe symptoms than A and B.

What about H1N1?

If you remember the news talking about Influenza H1N1 you probably know they were talking about Swine Flu. The H and the N stand for proteins that are attached to the Influenza A virus and therefore give it different subtypes. H1N1 however was important because it was the first pandemic the world had seen in over 40 years.

Flu symptoms

The flu is generally a respiratory virus. You will likely suffer from headache, congestion, sore throat and cough. Fevers, fatigue, and body aches typically accompany these symptoms and last 5-7 days. Many have had the flu in their lives and are familiar with the complete loss of energy and relentless body aches. While the body aches and fevers generally dissipate after 5-7 days, a lingering cough, congestion or sore throat may stick around for a week or two.

In your google searches you may come across articles that deny any gastrointestinal involvement with the flu. This is false. Although it is to a lesser degree, there are many patients that experience diarrhea and vomiting with the flu. This is not to be confused with the Stomach Flu, which is not caused by the influenza virus.

How to prevent the flu

The most obvious answer is to stay away from others with the flu. You may be smacking your head right now, but I cannot begin to tell you how many patients pack my waiting room for 1 day of sinus congestion, at the same time exposing themselves to the flu. During the winter, especially in the Northeast, I guarantee in an urgent care, there is a nearby patient with the flu sitting next to you.

Flu vaccine

The next preventative measure is the famous/infamous flu shot. Should you get it? Will it make you sick? The CDC recommends every one 6 months of age or older to receive the flu vaccine. But why? The reason is because the benefits greatly outweigh the risks.

The flu vaccine will cause your body to make antibodies to the influenza A and B viruses thereby equipping your natural defenses should you come in contact with the viruses.

Yes, it can be dangerous in patients with certain allergies (especially eggs) or a history of Guillan-Barre’ Syndrome. Becoming infected with the flu however is potentially life threatening especially in the young and elderly. The hardest statistic to measure is how many times an event does not happen. How many times did I personally avoid the flu because of the vaccine? I couldn’t tell you, but I examine infected patients almost daily during flu season, and have only had a mild case of flu A once over the last 3 years.

Won’t the flu vaccine cause me to become sick?

More than likely, no! You most likely will receive the inactivated vaccine. Oculorespiratory syndrome has been reported occasionally 24 hours after administration of the inactivated influenza vaccine. It is a self limiting reaction characterized by bilateral conjunctivitis, facial swelling, and/or respiratory symptoms (wheezing, cough). While first described in the 2000-2001 season in Canada, the incidence has dropped substantially after manufacturing and formulation changes have been made.

The live vaccine (which you are less likely to receive) can cause a runny nose, congestion, headache and sore throat.

A true story

I once was feeling sick with cold symptoms myself. Unfortunately I had one day off from work and that was the day I planned on getting the flu vaccine. I decided not to tell the nurse (I don’t recommend) at CVS how I was feeling and received the shot any way. An hour later I felt like a million bucks, healthy as a horse for the rest of the day. Does that mean the flu shot made me better? No!

My point is that my experience was anecdotal. Just because I had a positive experience after receiving the flu shot does not mean the flu shot cures a sore throat and congestion. Likewise, just because one person becomes sick after receiving the flu shot, does not meant that the flu vaccine is responsible.

Why do I need the flu shot every year?

Like many viruses, the influenza viruses are highly mutable, meaning they mutate. The same vaccine this year is unlikely to work next year. Based on world wide surveillance of the virus, vaccine experts create a forecast for the most likely influenza viruses to circulate. If they are correct, there is a low incidence of the flu. If they are wrong, there is a “bad” flu season and patients groan.

“I have the flu? But I got the shot.”

Unfortunately you still may get the flu even though you were vaccinated. Is it an evil ploy by the pharmaceutical companies? It isn’t. It just means that the experts were off in their forecast and created a less effective vaccine that doesn’t match the circulating influenza viruses. Still many speculate that should you become infected with the flu during the same season you received the vaccine, it is likely a less severe case.


Tamiflu is a prescription antiviral medication for influenza A and B. It can be given either to treat or prevent the flu. The prophylactic dose may be taken by a household member of a patient who has been diagnosed with the flu. I have mixed feelings about Tamiflu.

Diagnosing the flu

Rapid flu test

It’s going to get a little gross, but that swab needs to to go deep up your nostril. You might feel like there is a little brain matter on the end of it but I swear it’s just boogers. While there are numerous rapid flu tests for flu A and B that can be done in 15 minutes or less, they are inaccurate. Their sensitivity is low and there specificity at most is mediocre. This means that even though a rapid test is negative, that does not mean that one is not infected with the flu.

There are other non rapid test for the flu that are a bit more accurate. But by the time the results are back, you likely do not have the flu anymore, or are out of the window for treatment.

The flu is still diagnosed clinically. If the history and physical is consistent with the flu but the rapid test is negative, guess what? You have the flu. If you are sick with flu symptoms and your younger brother has the flu, but the test was negative, guess what? you have the flu.

Flu treatment


Tamiflu (Oseltamivir) is likely the most common prescription medication for the influenza A and B only. For treatment of the flu it is given within 48 hours from onset of symptoms and taken twice daily for 5 days. The benefit of taking Tamiflu is that it knocks off about a day of duration of the flu. It is generally well tolerated but can cause some gastrointestinal discomfort, mainly nausea. There are also very rare but serious side effects that include seizures, convulsions, and abnormal behavior, especially in children.

Xofluza (Boloxavir marboxil) is relatively new in the U.S. It will also lessen the duration of the flu and likely will do nothing for the severity. Like Tamiflu it is given within the first 48 hours from onset of symptoms. Unlike Tamiflu it is taken as a one time dose. It has similar gastrointestinal side effects which appear to be to a lesser degree than Tamiflu. Your insurance coverage unfortunately will likely dictate which antiviral is available for you.

Chicken soup and time

Of course you probably had the flu at one point in your life. You suffered, waited it out, kept up on your fluids, and here you are now, healthy and educating yourself as a patient. The flu is self limiting. It will improve with a little TLC.

Antivirals are not necessary. Antipyretics for fevers and aches, fluids, and rest are likely all you need. Warm fluids like tea with honey and chicken soup have effects on relieving airway irritation and preventing coughing.

How does the flu kill people?

As said before, the young and elderly are most at risk from the flu. There are 2 ways in which the flu can kill you. Like any infectious disease, the flu causes an immune response. By receiving the vaccine you are already ahead of the game should you become infected with the flu.

Fortunately our immune systems are fine tuned fighting machines. Unfortunately they get carried away sometimes and overreact. A reaction of the immune system causes inflammation in the body which leads to symptoms. An overreaction of the immune system can be deadly. In its efforts to eliminate the virus, immune cells can destroy healthy tissue, particularly the lungs where influenza likes to reside. Compromised lungs lead to less oxygen which ultimately can be fatal

Secondary infections are the other way in which the flu can kill. A bad infection with the flu can tie up the bodies defenses, leaving it open to other secondary infections. For this reason, it is not atypical to see a secondary bacterial pneumonia infect the lungs. Without proper antibiotic treatment, pneumonia can become fatal.


All this talk about flu can be nerve-racking. Remember the best treatment is to never become ill. If that still makes you anxious, remember that if you are a healthy adult, the odds are in your favor that you will survive another flu season and can come back to read some of my summer posts.

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