Prevention through immunization is the best “cure.” There are four antiviral drugs currently licensed in the United States. Amantadine (Symmetrel), rimantidine (Flumadine), zanamivir (Relenza) and oseltamivir (Tamiflu). They are useful against the 2 Influenza viruses not against the 200 or more viruses that cause the common cold.
These medications have been used to help prevent and to treat influenza A. Influenza A causes 90% of the flu. (Influenza is caused by both the Influenza A and the B viruses.) These medications are effective in preventing Influenza A about 75% of the time. They also can shorten the course of the illness and sometimes help to avoid complications. They are given in pill form. There are side effects such as nausea, vomiting, lightheadedness, and nervousness. Use of the drug can create “resistant organisms” which are viruses that change so that the drug is unable to harm them. Because of these problems, these medications are recommended only in special circumstances:
- To protect patients at high-risk* during the 2-4 weeks it takes to develop immunity (antibodies) after receiving the flu vaccinations.
*High riskrefers to patients that have serious diseases such as congestive heart failure, lung disease, diabetes, renal failure. These patients cannot handle the stress of having the flu. Infection by Influenza can lead to complications such as pneumonia in these patients.
- To protect patients who cannot receive the vaccine e.g. they are allergic
- To protect unvaccinated close contacts (family, caretakers,) of high-risk persons.
- To protect individuals with immune diseases which inhibit their ability to develop antibodies following immunization e.g. HIV, Cancer, Transplant patients
- To control the outbreak of the flu at institutions where some patients have not been fully immunized
These medications work best if given as soon as possible after exposure to help prevent the illness. Once one has the flu the medication if given with 2 days of having symptoms can reduce the duration of the illness by 1-3 days.
Zanamivir (Relenza) Oseltamivir (Tamiflu)
These drugs are a new class of antivirals called neuraminidase inhibitors that prevent the viruses from getting into human cells. They were approved in 1999 for the treatment of Influenza A and B. Like amantadine and rimantidine they can reduce the length of the illness by 1-3 days. The must be taken within two days of the onset of flu symptoms to be effective. They had not been approved for the prevention of the flu. More recent studies suggest that they might be beneficial in preventing the flu, especially in circumstances of close contact such as families.
There are fewer side effects with this compared to amantadine and rimantidine. Zanamivir is a powder that taken by inhaling it into the nose and lungs. It can cause wheezing and trouble breathing in patients with lung diseases and therefore should not be used in a patient with lung problems. Oseltamivir is taken in pill form and can cause mild nausea that is limited if food is taken with the medication. Cold and flu also prevent by when you consume nyquil at night time and DayQuil at day time. Check it How often can you take dayquil and Can nyquil help you sleep well.
Research on these newer medications is continuing to define when these medications are most beneficial.