In its "Take 3" Actions to Fight the Flu campaign, the Centers for Disease Control and Prevention (CDC) put "take time to get a flu vaccine" at the top of the list. According to the CDC, the flu shot can reduce the risk of flu by 70 to 90 percent in healthy adults. However, a flu shot can also cause complications that you should be aware of.
Injection Site Reaction
More than 10 percent of adults and children who receive the flu shot report injection site reactions. Symptoms of injection site reaction include localized muscle pain, tenderness, redness and swelling. In almost all cases, symptoms are mild and resolve without treatment within two days, according to product literature supplied by 2009-2010 Food and Drug Administration (FDA)-approved vaccine manufacturer Sanofi-Pasteur.
Flulike Illness
Mild flulike illness is reported in more than 10 percent of people who receive the flu shot. In clinical studies done by CSL Biotherapies Inc., makers of the Afluria seasonal flu vaccine, approximately 10 percent of adults complained of headache, muscle ache, fatigue and malaise after receiving the vaccine. Children reported a broader range of symptoms, including irritability, rhinitis, fever, cough, loss of appetite, vomiting, diarrhea, headache, muscle aches and sore throat. These symptoms were usually mild and resolved within five days.
Anaphylaxis
In very rare cases, the flu shot can cause a life-threatening allergic reaction known as anaphylaxis. According to MedlinePlus, symptoms of anaphylaxis appear within seconds or minutes of receiving the shot. They include difficulty breathing; abnormal heartbeat; nausea, vomiting and/or abdominal pain; hives or skin redness; and mental confusion or loss of consciousness. Anaphylaxis related to the flu shot may occur in people with allergies to eggs or the antibiotics neomycin, polymixin B and gentamicin, according to Afluria product literature. People with a history of anaphylaxis from flu vaccine should not be vaccinated again.
Guillain-Barre Syndrome
Guillain-Barre syndrome (GBS) is an autoimmune disorder in which the body makes antibodies against the coverings of the nerves. The 1976 swine flu vaccine was associated with an increased frequency of GBS, according to the CDC; about one in a million people who received the seasonal vaccine between 1992 and 1994 developed GBS. According to the National Institute of Neurological Disorders and Stroke, GBS initially presents with muscle weakness and tingling. Weakness gives way to paralysis that moves progressively up the body. Between 5 and 6 percent of people with GBS die, despite supportive care.
