The flu is relatively common—the U.S. Department of
Health and Human Services (DHHS) reports that the seasonal flu affects up to 20
percent of Americans each year. While many people can combat symptoms with
plenty of rest and fluids, certain high-risk groups may experience dangerous
and even life-threatening complications as a result of the flu.
The Centers for Disease Control and Prevention (CDC) estimate that between 3,000 and 49,000 people in the United
States die each year from the flu. The World Health Organization
(WHO) estimates that each year between a quarter to half a million people
worldwide die from flu complications.
According to a CDC study published in the Journal of the American Medical
Association, an average of 200,000 Americans required hospital care each
year (from 1979 to 2001) for respiratory and heart complications due to the flu
The study also found that flu-related hospital visits
increased with each year. One flu season, the number reached 430,960.
Those at High Risk for Flu Complications
The following groups are at
higher risk for the flu. According to the CDC,
these groups should receive first priority when there is a shortage of flu
High-risk individuals include
- between six months and five years of age
- 65 and older
- who are pregnant
- children and teens under 19 who receive aspirin
- with weakened immune systems due to disease (such
as cancer or HIV/AIDS) or long-term steroid medication use
- whose body mass index is 40 or higher
- with asthma
- with heart and lung conditions
- with other chronic health conditions, including
metabolic disorders, kidney disorders, blood disorders (sickle cell anemia),
liver disorders, endocrine disorders (diabetes), and those with neurological
and neurodevelopmental disorders (epilepsy, stroke, cerebral palsy)
Native Americans and Alaskan Natives are also at greater risk for flu
These groups should monitor their flu symptoms
closely. They should also seek immediate medical care at the first sign of
Flu and Those 65 and Over
People 65 and over are at greatest risk for flu-related
complications and death. The CDC estimates that more than 60 percent of flu-related
hospital stays and 90 percent of flu-related deaths occur in this age group.
This is why it is so important for these individuals to
receive a flu shot.
The flu shot’s ability to prevent flu may lessen a bit
with age. This is because the immune system’s response declines as we get
Still, the flu shot remains the best way to prevent flu
and its related complications.
The U.S. Food and Drug Administration (FDA) recently
approved a higher-dose vaccine, FluZone
High-Dose, for those 65 and over.
This vaccine contains four times the amount of antigens
as the normal flu vaccine. Antigens stimulate the immune system’s production of
antibodies, which fight the flu virus.
Complications of the Flu
Complications of the flu will often appear just as main
flu symptoms are subsiding. The flu can also make already-present health
The following complications may develop from the flu:
Pneumonia is a bacterial infection that causes the lungs
to become inflamed. This causes symptoms of cough, fever, shaking, chills, and
other side effects.
It is the most common complication of the flu, and can
be especially dangerous—sometimes deadly—for people in high-risk groups. These
groups include the very young, the elderly, and those with existing medical conditions.
Seek medical treatment immediately if you have any of the following
- severe cough with large amounts of mucus
- trouble breathing
- shortness of breath
- fever higher than 102°F that is not going
away—especially if chills or sweating are also present
- chest pains
- severe chills or sweating
This condition is typically highly treatable, often
with simple home remedies like sleep and plenty of warm fluids. However, the Mayo Clinic
points out that smokers, older adults, and people with heart or lung problems
are especially prone to complications associated with this condition. Further complications
from pneumonia include fluid buildup in and around the lungs, bacteria in the
bloodstream, and acute respiratory distress syndrome.
This complication is caused by irritation of the mucous
membranes of the bronchi in the lungs.
Symptoms of bronchitis include cough (often with mucus),
chest tightness, fatigue, mild fever, and chills.
Most often, simple remedies such as rest, drinking
plenty of fluids, using a humidifier, and taking over-the-counter pain
medications are all that’s needed to treat this complication.
However, contact your doctor if you
have any of the following symptoms:
- a cough that lasts longer than
- a cough that interrupts your sleep
- a cough combined with fever over
- a cough that produces mucus of a
- a cough that produces blood
- a cough combined with wheezing or
More serious conditions such as pneumonia, emphysema,
heart failure, and pulmonary hypertension can develop from untreated, chronic bronchitis.
Sinusitis is the swelling of the sinuses. Symptoms
include nasal congestion, sore throat, postnasal drip, pain in the sinuses,
pain in the upper jaw and teeth, a reduced sense of smell or taste, and cough.
Sinusitis can often be treated with over-the-counter
saline spray, decongestants, and pain relievers. Your doctor may also prescribe
a nasal corticosteroid like fluticasone (Flonase) or mometasone (Nasonex) to
Symptoms that warrant immediate
medical attention include:
- pain or swelling near the eyes
- swollen forehead
- severe headache
- mental confusion
- vision changes, such as seeing
- difficulty breathing
- neck stiffness
These may be signs of sinusitis that has worsened or
Better known as an ear infection, this condition is an
infection and swelling of the ear.
Symptoms include chills, fever, hearing loss, ear
drainage, vomiting, and mood changes.
According to the Mayo Clinic,
an adult with ear pain or discharge should see his or her doctor as soon as
possible. A child should be taken to his or her doctor if:
- symptoms last more than one
- ear pain is extreme
- you notice discharge from the
- your child is not sleeping or
is moodier than usual
This rare condition occurs when a flu virus enters the
brain tissue and causes swelling of the brain, which can lead to destroyed
nerve cells, bleeding in the brain, and brain damage.
Symptoms include severe headache, high fever, vomiting,
light sensitivity, drowsiness, and clumsiness.
Though rare, this condition may also cause tremors and
difficulty with movement.
Seek medical care immediately if you have any of the following
- severe headache or fever
- mental confusion
- severe mood changes
- double vision
- speech or hearing problems
Symptoms of this condition in young children include:
- protrusion in the soft spots
on an infant’s skull
- body stiffness
- uncontrollable crying
- crying that gets worse when
the child is picked up
- loss of appetite
- vomiting and nausea
Worsening of Existing Conditions
The flu can also worsen existing conditions, such as
heart, lung, kidney, or liver disease.
Long-Term Outlook for Those Who Develop Flu-Related Complications
A yearly flu vaccine is the best preventative
measure for those at high risk of flu-related complications. Practicing good hygiene
such as regular hand washing and avoiding or limiting contact with infected
people can also help prevent the spread of the flu.
Early treatment is also key to successfully treatment
of flu-related complications. Most of the complications mentioned above respond
well to treatment. However, many can become more serious without proper
Most flu symptoms resolve within one to two weeks. If
your flu symptoms worsen or do not subside after two weeks, call your doctor.