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The Inside Story of Tamiflu: Side Effects & Benefits

What is the bottom line on Tamiflu (oseltamivir) and Xofluza (baloxavir) for influenza? How well do they work? Are there side effects you should know about?
The Inside Story of Tamiflu: Side Effects & Benefits
Photo credit: ahisgett via photopin cc

Have you seen the commercial for Tamiflu (oseltamivir)? A very sick-looking man is seen creeping about in a very small house. He blows his nose with a teeny tissue. He’s so big he has to bend over to get into his tiny bathroom. The voiceover announcer says:

“Suffering from the flu is a really big deal. With aches, fever and chills there’s no such thing as a little flu. So why treat it like it’s a little cold? There’s something that works differently than over-the-counter remedies. Prescription Tamiflu attacks the flu virus at its source, so call your doctor right away.”

Oseltamivir is an oral antiviral medication that works by preventing the influenza virus from multiplying in the body, but there is a major controversy about the drug’s effectiveness.

How Tamiflu Works:

For the virus to penetrate human cells and then spread the infection to other cells throughout the body, it relies on an enzyme called neuraminidase (NA) that has a mushroom-like shape. The virus utilizes this enzyme to bust out of the host cell and spread lots more viruses (and chaos) throughout the body.

Tamiflu is an NA inhibitor. By blocking the NA enzyme the drug makes it harder for the influenza virus to escape a host cell and replicate.

As good as this sounds, you have to take the drug within the first day or two of symptoms. Once the flu takes hold, there are way too many viruses circulating in the body to stop the infection. For Tamiflu to work, you have to keep the number of infected cells under control so that the immune system won’t be overwhelmed.

How Well Does Tamiflu Work?

The Pros:

The crux of the Tamiflu controversy centers on the drug’s effectiveness. The Centers for Disease Control and Prevention (CDC) state that:

“Antiviral medications with activity against influenza viruses are an important adjunct to influenza vaccine in the control of influenza.”

Influenza vaccines are created anew each year, with the aim of matching that year’s circulating influenza virus strains. Flu viruses are notoriously given to mutation, and they change frequently. In 2014, for example, the vaccine against H3N2 (the predominant flu strain that year) was not a good match against the virus. It makes sense for the CDC to encourage other options in addition to vaccine. The public health experts there went on to say:

“Influenza antiviral prescription drugs can be used to treat influenza or to prevent influenza.”

They expected Tamiflu to reduce the severity of both type A and type B influenza and shorten the duration of the illness. Those who take the drug prophylactically (say when a spouse or child gets influenza) are supposed to be able to prevent the flu from taking hold in the first place.

A study published in The Lancet Respiratory Medicine (March 19, 2014) reported that Tamiflu was helpful during the 2009-1010 swine flu epidemic. The researchers evaluated data from dozens of studies involving nearly 30,000 patients who had been hospitalized with H1N1 influenza. These were severely ill people.

Those who received Tamiflu during their hospitalization were 25 percent less likely to die compared to patients who did not get the antiviral medication. If influenza-infected patients got Tamiflu within two days of the onset of symptoms, their likelihood of dying was halved. The lead investigator suggested that the earlier Tamiflu is used during an influenza epidemic, the more effective it will be in reducing severe illness or death.

A more recent study showed that oseltamivir is equally effective as a newer antiviral drug developed against influenza, zanamivir (Marty et al, The Lancet Respiratory Medicine, Feb. 2017). These were patients hospitalized with severe influenza. They responded to the drug in just over five days.

The Cons:

The Cochrane Collaboration is an independent network of health professionals who sift through scientific evidence to determine the safety and effectiveness of various treatments. On April 9, 2014, Cochrane researchers published a report in the BMJ on Tamiflu and another NA inhibitor called Relenza (zanamivir). The Cochrane Collaboration concluded:

“Compared with a placebo, taking Tamiflu led to a quicker alleviation of influenza-like symptoms of just half a day (from 7 days to 6.3 days) in adults, but the effect in children was more uncertain. There was no evidence of a reduction in hospitalisations or serious influenza complications; confirmed pneumonia, bronchitis, sinusitis or ear infection in either adults or children. Tamiflu also increased the risk of nausea and vomiting in adults by around 4 percent and in children by 5 percent. There was a reported increased risk of psychiatric events of around 1 percent when Tamiflu was used to prevent influenza.”

Tamiflu (oseltamivir) Side Effects:

  • Digestive upset (nausea, vomiting, diarrhea, stomach pain)
  • Headache
  • Nosebleeds
  • Psychiatric symptoms (hallucinations, abnormal behavior, self harm)
  • Skin reactions (any rash or allergic reaction must be reported immediately as it could become very serious)

A New Flu Drug: Xofluza (Baloxavir)

There’s a new kid on the block. Baloxavir (Xofluza) is also advertising on television. This treatment for influenza was approved by the FDA in the fall of 2018. The commercials states:

“The flu sucks…everything out of you. The fever, aches and chills can flatten you fast. Prescription Xofluza can help you feel better in just over two days. Over-the-counter medicines just treat symptoms. Xofluza is different. It attacks the flu virus at its source with just 0ne dose…

“The most common side effects are bronchitis, nausea, diarrhea, sinusitis and headache.”

Xofluza is not cheap. Two pills (taken at the same time) could cost around $180. that’s the bad news. The good news is, that’s it! You only have to take one dose (two pills) and y0u are done. It’s still expensive. 

How good is Xofluza? Well, it’s not magic. Here is what Consumer Reports (Oct. 25, 2018) has to say:

“The data from clinical trials suggest that Xofluza, approved for most healthy people over age 12, works about as well as oseltamivir (Tamiflu and generic)—the most commonly used flu treatment currently available—at reducing the length of a flu illness. Overall, both appear to cut the time people have flu symptoms from a little over three days to a little over two days.”

We told you. Xofluza is not a magic pills against influenza. 

People’s Pharmacy Analysis

We are great admirers of the Cochrane Collaboration and we do not doubt that its analysis of Tamiflu was independent and objective. In the clinical trials that were analyzed, the drug only appeared to shorten the duration of the flu by about a day at best, and did not seem to prevent serious complications of influenza. That contradicts the conclusions of the study described above in The Lancet Respiratory Medicine.

We have used Tamiflu ourselves on several occasions and our subjective opinion is that the drug actually does speed healing and lesson symptoms. Personal experience, of course, is not scientific. Here are some other reports from visitors to our website:

D.P. writes:

“Twice in the last 10 years my husband was diagnosed with flu. A few days later I became ill with fever and flu symptoms. I went to the doctor and was given Tamiflu. I never got really sick. I was better in 48 hours; faster than my husband who was not given Tamiflu. (I think he will take it now if he gets it again.)”

Mel offers this story:

“When my son came down with R1N1 a few years ago, he was prescribed Tamiflu. As a child with Juvenile Idiopathic Arthritis he was in the ‘at risk’ category because he was taking immune suppressing drugs. Tamiflu worked well and he was better in about 1 ½ days.

“My daughter and I have asthma, and were also prescribed Tamiflu when we came down with the same virus. It worked well for us, too (2 days-4 days duration). As a mom, it was a big relief.”

J.E.C shared a similar experience:

” I had the same experience a few years ago. While my husband had suffered with severe flu symptoms for about a 2-week period, I called the doctor as soon as I became ill and was prescribed Tamiflu. My symptoms, which were much milder, only lasted about 2 days. I’m a believer – it’s good stuff.”

J.A.S. writes:

“I caught the flu several years back and was prescribed Tamiflu within 48 hours of my symptoms appearing. I absolutely HATE taking any prescription or OTC drugs, but I did take the Tamiflu not knowing anything about it at that time.

“My symptoms lessened promptly and I felt better so quickly I was very surprised. Perhaps I had a mild case of the flu, but I do remember that Tamiflu had a relatively quick response and seemed to have stopped this flu infection dead in its tracks. I doubt if it was a placebo effect because I was soooo reluctant to take it and didn’t exactly have a positive outlook about it.”

Xofluza Stories:

Lonny is pretty cynical:

“The side effects of the flu drugs are the symptoms of the flu. So if you don’t feel bad enough already, you can take a drug to make you feel worse. And pay a small fortune for the drug. Sounds to me like an advanced case of stupidity.”

Linda and her husband weren’t thrilled with the outcome:

“My husband and I returned from a trip to Europe with a strain of the flu apparently not covered by our flu vaccine. We took Xofluza and after three doses, both of us developed diarrhea and abdominal cramping. We stopped taking the meds, and the symptoms stopped. The headache, congestion, and body aches of the flu were bad enough without adding the diarrhea caused by expensive meds.”

The Bottom Line on Tamiflu & Xofluza:

Tamiflu is not a miracle medicine against influenza. Neither is Xofluza. The clinical trial data suggest that these drugs are modestly effective at shortening the duration of the flu. They do have side effects (predominately digestive in nature). According to Cochrane, about 4 to 5 percent of people taking Tamiflu experienced nausea or vomiting and about 1 percent developed psychological side effects when they took the drug to prevent the flu.

That said, there is evidence that people do benefit from Tamiflu and Xofluza, especially when these drugs are taken as soon as possible after developing symptoms. If the vaccine does not live up to expectations, Tamiflu or Xofluza may be worth consideration in the fight against influenza.

If you would like to read about some other options, you may find our Guide to Colds, Coughs & the Flu of interest.

photo credit: ahisgett via photopin cc

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About the Author
Joe Graedon is a pharmacologist who has dedicated his career to making drug information understandable to consumers. His best-selling book, The People’s Pharmacy, was published in 1976 and led to a syndicated newspaper column, syndicated public radio show and web site. In 2006, Long Island University awarded him an honorary doctorate as “one of the country's leading drug experts for the consumer.” .
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