In its "Take 3 Actions to Fight the Flu" campaign, the Centers for Disease Control and Prevention (CDC) lists take time to get a flu vaccine as the number one thing individuals can do to reduce their risk of getting the flu. In healthy adults, the flu injection may reduce the risk of flu by 70 to 90 percent. However, educated consumers often want to know about flu injection symptoms.
Injection Site Symptoms
Following the flu injection, many people have symptoms at the injection site. In clinical trials for the FDA-approved vaccine Afluria, the most common symptoms were tenderness (60 percent), pain (40 percent), redness (16 percent), swelling (9 percent) and bruising (5 percent). In 99 percent of cases, these symptoms were rated as "mild" or "moderate" and did not interfere with activities. Similarly, with the exception of bruising, almost all symptoms resolved within two days.
Systemic Symptoms
A smaller number of people report systemic symptoms similar to those of the flu. In clinical studies for FDA-approved injection Flulaval, the most common symptoms were headache (18 percent), fatigue (17 percent), generalized muscle pain (13 percent), fever (11 percent), malaise (10 percent), sore throat (9 percent), eye redness (6 percent), cough (6 percent), chills (5 percent), chest tightness (3 percent) and facial swelling (1 percent). As with injection site symptoms, 99 percent of symptoms were rated as "mild" or "moderate" and, in almost cases, symptoms resolved within two days. Symptoms were less common in the elderly than they were in younger adults and children. Children experience more diverse symptoms including irritability, nasal irritation, loss of appetite, nausea, vomiting and diarrhea.
Symptoms of an Allergic Reaction
The flu injection occasionally triggers allergic reactions. Symptoms of an allergic reaction may include itching, rash, hives, wheezing/asthma and swelling in places other than the injection site. According to product literature supplied for each of the FDA-approved flu injections, each of the vaccines has also been associated with more serious allergic syndromes including angioedema and anaphylaxis.
The main symptom of angioedema is the sudden appearance of swelling below the skin, according to MedlinePlus. Commonly affected areas include eyes, lips, hands, feet and throat. Swelling may be painful and sometimes itchy. In most cases, angioedema resolves without treatment. However, sometimes swelling of the throat can lead to life-threatening breathing problems or angioedema may be a precursor to anaphylaxis.
Anaphylaxis is a life-threatening, whole-body allergic reaction that often begins within seconds or minutes of exposure to an allergen. According to MedlinePlus, symptoms of anaphylaxis include abdominal pain or cramping, anxiety, confusion, cough, diarrhea, breathing problems, fainting, light-headedness, dizziness, hives or itchiness, nasal congestion, nausea or vomiting, heart palpitations, slurred speech and wheezing. Without emergency medical care, anaphylaxis can progress rapidly to respiratory failure and cardiac arrest. People who have an allergic reaction to the flu injection should always inform their health care providers.
