Colds and the Flu - Complications

Complications

Colds rarely cause serious complications. In about 1% of cases, a cold can lead to other complications, such as sinus or ear infections. It can also aggravate asthma and, in uncommon situations, increase the risk for lower respiratory tract infections.

Ear Infections. The rhinovirus infection, a major cause of colds, also commonly predisposes children to ear infections, possibly by blocking the Eustachian tube, which leads to the middle ear. Viruses may even attack the ear directly.

Sinusitis. Between 0.5 - 3% of people with colds develop sinusitis, an infection in the sinus cavities (air-filled spaces in the skull). Sinusitis is usually mild, but if it becomes severe, antibiotics generally eliminate further problems.

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Lower Respiratory Tract Infections. The common cold poses a risk for bronchitis and pneumonia in nursing home patients, and in other people who may be vulnerable to infection.

Aggravation of Asthma. Rhinovirus infections can aggravate asthma in both children and adults. In fact, rhinovirus has been reported to be the most common infectious organism associated with asthma attacks. Problems with wheezing may persist for weeks after a cold.

Complications of Influenza

The flu is usually self-limited. However, each year in the United States, more than 200,000 people are hospitalized due to complications of the flu. An estimated 36,000 people die each year of influenza-related complications. People at highest risk for serious complications from seasonal flu are those over 65 years old and those with chronic medical conditions. Influenza A is the most severe strain. Influenza B tends to be milder.

Unlike the seasonal flu, children younger than 5 years old, especially those younger than age 2, with H1N1 (swine) flu are also at risk for more serious complications. Pregnant women with H1N1 influenza are also at increased risk for complications.

Pneumonia. Pneumonia is the major serious complication of influenza and can be very serious. It can develop about 5 days after the flu. More than 90% of the deaths caused by influenza and pneumonia occur among older adults.

Flu-related pneumonia nearly always occurs in high-risk individuals. It should be noted that pneumonia is an uncommon outcome of influenza in healthy adults.

Complications in the Central Nervous System in Children. Influenza increases the risk for complications in the central nervous system of small children. Febrile seizures are the most common neurologic complication in children. The risks decline after a child turns 1 year old, but are still high in children aged 3 - 5 years old.

Review Date: 01/29/2011
Reviewed By: Harvey Simon, MD, Editor-in-Chief, Associate Professor of Medicine, Harvard Medical School; Physician, Massachusetts General Hospital. Also reviewed by David Zieve, MD, MHA, Medical Director, A.D.A.M., Inc.

A.D.A.M., Inc. is accredited by URAC, also known as the American Accreditation HealthCare Commission (www.urac.org).