Why Do I Feel Tired After A Flu Shot? It’s A Common But Not Serious Side Effect

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This flu season has hit the United States hard, and there are still more weeks to come in this particularly dangerous season. Thus far, the CDC reports that 37 children have died from flu complications. There’s also been 11,965 laboratory-confirmed flu-related hospitalizations reported between Oct. 1 and Jan. 20, and that number doesn't include all the people who get sick but don't visit a doctor. If you’re thinking about getting a flu shot, you’re in good company. A flu shot can make you less likely to get sick, make your illness more mild if you do get sick, and prevent others around you who aren't able to get the flu shot from getting ill, thanks to herd immunity. But there are certain side effects of getting a flu shot: many people complain of feeling tired after getting a flu shot, but that isn't a cause for worry (or a reason not to get vaccinated).

Dr. Gustavo Ferrer, the founder of the Cleveland Clinic Florida Cough Center, tells Bustle that the tiredness some people feel is a result of “the body’s defenses (immune system) responding to the dead virus present in the vaccine." He further explains, “The symptoms are the result of the antibodies produced by our body in order to build up an immune response. In essence, a foreign substance (dead virus) ​entering our body that our defenses recognize and respond with fatigue, tiredness, low-grade fever, and lousiness. These symptoms last a couple of days.”

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Some folks on Twitter are experiencing the exact symptoms Dr. Ferrer describes. Isabel Marcus tweeted, “I got the flu shot, which is good, but my head hurts and my arm hurts, and I feel so tired I might fall out of my bed right now.”

CDC officials state, “The most common side effects from the influenza shot are soreness, redness,and tenderness or swelling where the shot was given,” and emphasize that “the risk of a flu shot causing serious harm or death is extremely small.” But the actual flu can cause serious harm or potentially lead to death.

For a typical year, the CDC estimates 9 million to 35 million flu-related illnesses, 140,000 to 710,000 hospitalizations, and 12,000 to 56,000 deaths in the United States. Worldwide, flu statistics are even more dire. The World Health Organization estimates that the flu is responsible for 3 to 5 million cases of severe illness, and around 290,000 to 650,000 deaths.

The CDC estimates that one in five people get the flu each year, so the odds that you or someone you’re close with will get the flu are pretty high. The CDC also estimates that flu vaccinations can decrease flu-related visits to medical facilities by about 60 percent, but some people refuse to get a flu shot due to its potential side effects, like feeling tired or sore afterwards. Feeling tired and sore isn't pleasant, but the benefits of the flu shot definitely outweigh the risks.

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There are some ways to combat that tired feeling, according to Dr. Ferrer. First, he recommends that you take it easy. “This is the time to rest. Don’t push through. You need time to restore your energy.” He also suggests drinking plenty of fluids. “Keep yourself hydrated. The body loses a lot of fluid while mounting the immune response. Keep the muscle hydrated.” Dr. Ferrer says the best things to drink are plain water, coconut water, and tea, and emphasizes you shouldn’t drink “sugary drinks or sodas.”

The flu is a serious virus that is making a lot of folks sick and even killing some people, so it’s really important to protect yourself and those you’re around by getting the flu shot. There may be some negative side effects, but don’t let that stop you from giving yourself a better chance of staying healthy this flu season.