What Are the Most Common Side Effects of a Flu Shot?

7 answers | Last updated: Nov 04, 2015
A fellow caregiver asked...

What are the most common side effects of a flu shot?

Expert Answers

Dr. Leslie Kernisan is a senior medical editor at Caring.com and a clinical instructor in the University of California, San Francisco, Division of Geriatrics. She also provides housecalls and geriatric consultations in San Francisco.

The possible side effects depend on which type of vaccination you get. There are two ways to be vaccinated against the seasonal flu: You can get the intramuscular injection (commonly called the flu shot) of inactivated influenza, which contains killed virus. Or you can get the nasal spray vaccine (also known as FluMist), which contains live but weakened influenza vaccine.

The flu shot can cause a sore arm, and it sometimes causes mild fever, achiness, and fatigue that can feel like a mild case of flu to some people. But those symptoms generally don't last for more than a day or two. The nasal vaccine has been linked to symptoms such as runny nose, cough, and sore throat.

Both vaccine types contain traces of chicken eggs, which can be a problem for those with egg allergies.

You should know that only the inactivated influenza vaccine (the shot) is recommended for adults older than 50, or for those with known weakened immune systems (such as those with HIV).

Keep in mind that even though it's not uncommon to notice some mild side effects in the days after you get a flu vaccine, the risks associated with not getting vaccinated -- and getting the flu -- are quite serious. On average, every year 36,000 Americans die from seasonal influenza.

If you're younger than 50, talk to your doctor to help you decide which form of vaccination makes the most sense for you.

Community Answers

A fellow caregiver answered...

on oct.19,2010. i went to my dr.i was in good health on the visit i was offered the flu shot and was givin n1h1 vaccination in my left arm. shortly after i felt stiffness in my right elbow and excruciating pain where i could not extend my arm. i also had a burning sensation and soreness on the bottom of my feet.this continued for two days,i started having aches and pains thru out my body severe cough with thick mucus sweating, severe headache vomiting,fever,loss of appetite, chills.i took cold medicines over the counter thinking i just developed a bad cold and it would go away with rest.eventually the cough became stronger and persistant i started hearing ringing in my ears and i couldnt sleep at night.finally my mom said i should go to the hospital.i went to the emergency room nov.7,2010 dr. said i had the flu.i was puzzled because i had the shot.i was givin i.v. fliuds for dehydration narcotic meds for cough and pain.i immediatly felt some relief and after several days i returned to my dr. he examined me and told me i had an adverse reaction to the shot.and after doing my research and talking with other people there are others that suffered taking this vaccine.while i am recovering at this time this is the worse ive ever experienced i hope i still have a job cause i been out sick so long.this is the worse experience ever and if i had to go back to oct.19, i would say no to n1h1

Jady answered...

I received the injection on October 6, 2010. I've received the flu vaccine every year but this one was different. I experienced the "mild side affects" for the first time (i.e. fever, aches, chills) but it was the horrible arm pain that I still have to this day that concerns me. I can hardly use the injected arm due to extreme muscle weakness and pain. Some days are better than others but it has yet to go away.

A fellow caregiver answered...

Dr, thanks for the informative answer.

Sharon king answered...

Sorry to say this, but from the self-reports I am reading, it sounds like there was more a problem with the way in which the injection was administered than with the content itself. It is possible that the personnel who administer can vary in experience doing this: I have seen some pretty poor phlebotomists who cannot draws blood. So there should be some micromanagement over those who administer.

Ggravitas answered...

"On average, every year 36,000 Americans die from seasonal influenza." ... Where did you get that number? The CDC states it can't substantiate an exact number of deaths actually resulting from influenza. In fact, in its most recent study, the best it could do is provide a range, and that range is for 30 years. From 1976 to 2007 the CDC estimates 3,000 to 49,000 flu-related deaths. That's over 30 years!

The CDC also states it can more accurately estimate the number of hospitalizations each year, but not deaths. Nevertheless, in the H1N1 pandemic of 2009-2010, the CDC estimated--in one of the worst flu seasons we've had, 12,469 deaths of Americans that year. So I'm curious as to your source for that 36,000/year number.


A fellow caregiver answered...

I got a flu shot Oct 2015 which is the type that protects against four types of flu. Afterward I was OK, until the next morning when suddenly I felt so weak and tired, like extreme exhaustion, that I slept for a straight 14 hours.I woke up with soreness, and feel asleep again three hours later for another 12 hours. The second day I woke up nauseous and still tired. My left arm is very sore moreso than in past years, and I'm still recovering. It does not feel like the flu at all, it feels like side effects of the vaccination for sure, as I was fine before that.