- Oseltamivir Phosphate (Tamiflu)
- Zanamivir (Relenza)
What Do They Do in the Body?
Both drugs are neuraminidase inhibitors. They inhibit enzyme activity in flu viruses, which in turn inhibits their growth and spread. Relenza is inhaled and Tamiflu is taken as a pill. They have to be taken within 36 to 48 hours of the onset of flu symptoms to be effective. Even when taken within this time frame, studies show only a one to one and a half day shortening of the illness’ duration on average.
Keep in mind that these medications do not prevent you from passing the flu on to others.
Although Tamiflu has been approved for preventing the flu, studies suggest only a small benefit of neuraminidase inhibitors for prevention, if any at all.
What Are They Used For?
Treatment or prevention of influenza.
What Are the Possible Side Effects/Adverse Effects?
Tamiflu: Nausea, vomiting, insomnia, and vertigo. Rarely, unstable angina, anemia, colitis, pneumonia, and tonsil abscesses have occurred. Additional side effects have been reported in children, including abdominal pain, nosebleed, ear disorders, and conjunctivitis.
Relenza: Malaise, fever, abdominal pain, muscle pain, joint pain, itching, and dizziness. In children without the flu who received the drug as a preventive, far more adverse effects were reported, including nasal symptoms, throat/tonsil discomfort or pain, and cough.
Tamiflu and Children
A few years after its approval by the FDA, 25 people under the age of 21 had been reported to have died while using Tamiflu. Around 600 reports came in about abnormal behavior, hallucinations, and convulsions in people between the ages of 10 and 19 who were taking this oral neuraminidase inhibitor. (Most of these took place in Japan, where these medicines are much more widely used.) In two separate instances, a 12-year-old and a 13-year-old jumped out of a second-floor window after taking Tamiflu; others fell from windows or balconies or ran into traffic.
Relenza has been the subject of at least 115 reports of psychiatric side effects as well.
CAUTION! Think Twice About Taking These Drugs If…
You have been symptomatic for more than 40 hours. No studies have shown that neuraminidase inhibitors work once flu has progressed this far.
You have asthma or other chronic lung disease. In some asthmatics, zanamivir (Relenza) caused their airways to constrict. Adverse events are more common in people with pulmonary disease, and the drug has not been shown to help them.
Some strains of flu are not affected by these drugs. If you happen to be infected with one of these strains, the drugs will not help treat it.
Excessive use of these drugs, both individually and in the general population, will encourage the growth of drug-resistant flu viruses. Remember, a virus can mutate into a weaker version or a stronger version. Widespread use of flu drugs tends to create viruses that are resistant to the drugs.
The research on the effectiveness of these drugs is very mixed. According to a 2006 Cochrane review that examined the effectiveness of these flu drugs, “compared to placebo, [these drugs] have no [significant] effect against influenza-like illnesses.”
To find out more about how to prevent and treat the flu naturally, please read Flu Fighters.
Jefferson T, Demicheli V, Di Pietrantonj C, Jones M, Rivetti D, “Neuraminidase inhibitors for preventing and treating influenza in healthy adults,” Cochrane Database of Systematic Reviews 2006, Issue 3.
This article was excerpted in part from the book Prescription Alternatives by Earl Mindell and Virginia Hopkins