Colds and the Flu - Medications

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Limitations. Drawbacks of M2 inhibitors include:

• They are not effective against the 2010-2011 flu strains.
• Viral resistance to these agents is rapidly increasing.
• M2 inhibitors are not effective against influenza B.
• Neither drug has proven to reduce the risk for complications of the flu, including pneumonia and bronchitis.

Side Effects. Both M2 inhibitors occasionally cause nausea, vomiting, indigestion, insomnia, and hallucinations. Amantadine affects the nervous system and about 10% of people experience nervousness, depression, anxiety, difficulty concentrating, and lightheadedness. Rimantadine is less likely to do so. Rarely, amantadine can cause seizures.

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Note: Amantadine is a standard treatment for Parkinson's disease and should be continued for that condition.

Viral Influenza Vaccines

"Flu Shots." These vaccines use inactivated (not live) viruses. They are designed to provoke the immune system to attack antigens found on the surface of the virus. (Antigens are foreign molecules that the immune system specifically recognizes as alien and targets for attack.)

Unfortunately, the antigens in these influenza viruses undergo genetic changes (called antigenic drift) over time, so they are likely to become resistant to a vaccine that worked in the previous year. Vaccines are then redesigned annually to match the current strain.

• Influenza A. The influenza A virus is further categorized by primary molecular antigens (hemagglutinin and neuraminidase), which serve as the targets for the vaccines. Influenza A is a particular problem, because it can infect other species, such as pigs or chicken, and undergo major genetic changes.
• Influenza B viruses tend to be more stable than influenza A viruses, but they too vary. Although influenza B has been far less common than A, a vaccine for type B is important because experts are concerned that small children will not have developed any immunity to the virus, and will experience severe flu if they are exposed to type B viruses.

Intranasal (inside the nose) vaccine. A live but weakened intranasal vaccine (FluMist) is proving to be effective and safe in healthy, non-pregnant people aged 2 - 49 years and has been approved by the FDA. It is known as a live, attenuated, intranasal influenza vaccine (LAIV). The vaccine is engineered to grow only in the cooler temperatures of the nasal passages, not in the warmer lungs and lower airways. It boosts the specific immune factors in the mucous membranes of the nose that fight off the actual viral infections. FluMist is given using a nasal spray. It should NOT be used in those who have asthma or in children under age 5 who have repeated wheezing episodes.