The flu affects roughly 8 percent of Americans every year. In the majority of cases, flu is self-limited and the symptoms resolve within a couple of weeks, without lasting effects. However, some people- especially those at high risk may develop complications, which can be severe, life-threatening at times. As per the Centers for Disease Control and Prevention (CDC), between 3000-49,000 Americans die yearly from complications of the flu. Read on to learn more about the possible complications of flu, including common and rare, but serious conditions.
Potential complications of flu
- Ear infections following a flu affect the middle ear and cause ear pain, troubles hearing and drainage of fluid from the affected ear. Children can also experience fever, loss of balance, ear pain and become more irritable and fussy. In very rare cases, ear infections can spread to the membrane that surrounds the brain, causing meningitis.
- Sinus infections. In normal conditions, sinuses are filled with air. However, they can become inflamed and filled with fluid following a flu. These changes promote bacterial growth. Symptoms of sinusitis include pain around the face and eyes, headaches, stuffy nose with a mucus that can be thich, yellow and smelly, postnasal drip, fever and cough.
- Acute bronchitis or chest cold is the infection of the airways and can complicate a common cold or a flu. Symptoms include a persistent hacking cough, with or without mucus, chest congestion and discomfort, sore throat, fatigue, headache, muscle aches and pains. More details about chest cold in this article .Bronchitis, sinus and ear infections are considered “moderate” complications of a flu.
- Pneumonia is the infection of the lungs, and one of the most serious complications of a flu. Pneumonia can be caused by the virus or a secondary bacterial infection. Typical symptoms include cough , fever, chest discomfort, fever and chills. In elderly, pneumonia can cause confusion, digestive symptoms like nausea and vomiting and lower than normal body temperature. If left untreated, pneumonia can further complicate with sepsis (bacteria in the bloodstream) and organ failure. It is important to seek medical treatment right away if the cough becomes severe with excessive mucus, if there is significant breathing difficulty, chest pain and fever higher than 102°F .
- Acute respiratory distress syndrome (ARDS). ARDS is a rare, but life threatening complication. It is more likely to develop in very ill, hospitalized individuals after a flu or pneumonia. Significant shortness of breath, rapid, labored breathing, low blood pressure, confusion and extreme fatigue are the common symptoms of ARDS. This condition has to be treated promptly in the hospital with supplemental oxygen, IV fluids and medication.
- Myocarditis. Myocarditis is the inflammation of the heart muscle. It is a rare, but potentially serious complication of the flu and other viral infections. Symptoms can mimic a heart attack and include shortness of breath, heart palpitations, chest pain and lightheadedness. Severe myocarditis is associated with increased risk of heart failure, heart attacks and strokes. Overall, myocarditis is the reason behind 45% of heart transplants in the US and a leading cause of sudden death in children and young adults, according to Myocarditis Foundation.
- Encephalitis is another serious complication of flu. Headache, fever, aches and pains and fatigue are experienced in mild forms of encephalitis. In babies and young children, encephalitis can cause bulging of the fontanels, body stiffness, poor feeding, nausea and vomiting. Severe forms are associated with confusion, agitation, seizures, muscle weakness and even loss of consciousness.
- Other possible, serios complications of flu include inflammation of the muscle tissue, including a severe, life threatening form called rhabdomyolysis. Another serious complication is so called multiorgan failure, with severe lung and kidney damage, as well as sepsis. Furthermore, a flu can trigger flare ups of preexisting conditions like asthma, chronic obstructive pulmonary disease (COPD) or heart diseases.
Who is at risk to develop complications of flu?
For young and healthy individuals, the flu usually does not cause serious complications. The symptoms may be severe for a few days, and gradually improve and completely resolve in a week or two. However, certain groups of people need to be cautious and seek medical treatment if the flu symptoms are getting worse or new symptoms suggest a flu complication.
As per CDC, there are certain risk factors including age and pre-existing conditions that increase the chances of getting complications after the flu. Older adults over 65 and children age 5 or younger and those with chronic diseases like asthma, heart diseases, diabetes, liver and kidney diseases. Individuals with weakened immune systems due to a disease or immunosuppressant drugs, and those with excess weight and body mass index over 40 are also at increased risk. Keeping a chronic condition well managed (for example keeping blood sugar levels under control in case of diabetes) can greatly reduce the risk of complications. Flu vaccines are widely available in the US- more details about different types of flu vaccines are in this article.