5 Flu Shot Side Effects You Need To Know About Before You Get One

We get our flu shot to avoid being sick with the flu, so it feels pretty unfair when the flu shot itself gets us sick. But for infants and people over 65, they may be more prone to contracting the illness. And though healthy people don't usually die from influenza, and even though you yourself may not become ill, getting the flu shot can prevent others from getting it!

But before you go to the doctor or a pharmacy that offers a flu shot, there are still some flu shot side effects to keep in mind. Constantine George, MD, who is board certified in Internal Medicine and Pediatrics, says, “Side effects of the flu vaccine are generally mild and go away on their own within a few days.”

But that doesn’t mean there aren’t plenty of additional flu shot reactions and side effects.

Common side effects can include soreness, redness, and/or swelling from the shot, headache, fever, nausea, muscle aches, and like other injections, can occasionally cause fainting. “With any vaccine you should look for any unusual conditions, such as a high fever, behavior changes, or signs of a severe allergic reaction after vaccination,” warns Dr. George.

It's important to be aware of what's happening in your body after getting a flu shot. As Dr. George advises, “Severe allergic reactions can include difficulty breathing, wheezing, swelling around the eyes or lips, hives, paleness, weakness, dizziness or a fast heartbeat. Life-threatening allergic reactions to the flu shot are rare, and the signs would most likely happen within a few minutes to a few hours after the vaccine is given.”

It's clear there's a lot that can happen, but what are the other side effects of a flu shot? Here are some of the most common.

1. Injection bruising

No matter what sort of injection you get, there's bruising or reactions that can sometimes happen at the injection sight. “Side effects of the flu shot can include injection site reaction of redness, pain, and swelling,” says cardiologist Adam Splaver, MD.

It should be nothing to worry about, and the bruising will go away in a week or two.

2. Flu-like symptoms

For some, the reactions to the flu shot feel something like the flu itself. But you shouldn't worry, because it's not actually the flu. Still, it can feel pretty awful.

“Some flu shot recipients may have aches, pains and even spike a fever, as if they are coming down with the flu. But it is only temporary, with the symptoms usually fading away within 24 hours,” Dr. Splaver says.

3. Guillain Barre

For others, though, in very rare cases, the reactions can be very serious. "In very rare circumstances, recipients could come down with Guillain Barre, a serious and potentially neurological disorder,” warns Dr. Splaver.

Guillain Barre is extremely rare, and is a syndrome in which the body's immune system attacks the nerves. See a doctor immediately if you experience tingling moving up your body, choking on your saliva, or having a shortness of breath when lying down, as this disorder is serious.

4. Allergies

Of course, the side effects can include an allergic reaction, meaning your body is rejecting the shot. That's no simple matter, though, and can be very serious.

Dr. Splaver warns, “There are also instances of allergic reactions to the flu shot, with minor symptoms like a rash or hives or a more major reaction like anaphylaxis.” Other symptoms can include dizziness, drop in blood pressure, face swelling, and fever.

5. Racing heart

Flu shots are important if you have heart disease because viruses like the flu can raise your blood pressure and put stress on your heart. However, a rare side effect of a flu shot is a racing heart, so if you do have heart issues, you may want to make sure the shot is administered at your doctor's office and not your local drugstore.

Aly Walansky is a NY-based lifestyles writer. Her work appears in dozens of digital and print publications regularly. Visit her on Twitter or email her at alywalansky@gmail.com.