Open And Closed Illustration Of Refrigerator

Tamiflu is a commonly prescribed antiviral medication, used to both treat and prevent the flu in those who may have been exposed to it. It is available in two dosage forms, capsules, and liquid suspension.

In terms of how long the liquid the Tamiflu suspension is stable and safe to give when left out of the refrigerator, it depends on which product you have:

  • The commercially available Tamiflu suspension (the product that is made directly by the manufacturer) is stable for 10 days at room temperature (up to 77℉).
  • Compounded versions of Tamiflu suspension (made by your pharmacist using Tamiflu capsules during times of shortage) are only stable for 5 days at room temperature (up to 77℉).

Most individuals will have the Tamiflu product direct from the manufacturer, but it is important to know if you have the compounded version instead since the room temperature expiration date is shorter! I discuss below why there are two different versions of Tamiflu suspension and how to store them safely.

Tamiflu Suspension And Compounded Tamiflu

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There is extensive published data on the stability of Tamiflu suspension, both at room temperature and under refrigeration.

It is extremely important to know, which type of Tamiflu suspension you were dispensed as stability varies based on which product you have.

The vast majority of people will have received the commercially available product, which is supplied directly from the manufacturer as a white powder blend in a glass bottle. With this product, your pharmacist will add water to reconstitute it when you pick it up.

There have been numerous times recently, however, where there has been a significant shortage of Tamiflu suspension (2013 was a particularly bad year, which was widely reported).

There was such a shortage in 2013 that the CDC (Centers for Disease Control) provided instructions for pharmacists on how to compound a suspension out of Tamiflu capsules (as they were more often available) when the commercially manufactured Tamiflu oral suspension formulation was not readily available.

Shortages of the liquid Tamiflu suspension happen often enough that, in 2013, the prescribing information for the drug was revised to add specific instructions for pharmacists on how to compound it if necessary.

In the next sections, I discuss how long both the commercially available Tamiflu suspension, and compounded version, are safe at room temperature and in the refrigerator.

Tamiflu Suspension (Manufacturer Labeled Product) Storage Requirements

If you accidentally left your bottle of Tamiflu (oseltamivir) suspension out of the refrigerator, that is okay! The reconstituted suspension (after the pharmacist adds liquid to the powder), is stable at room temperature (up to 77℉) for 10 days.

Since the length of dosing of Tamiflu is generally between 5 and 10 days, it is safe to simply store it in the refrigerator or leave out at room temperature for the duration of therapy.

There is no stability data after 10 days, so if the prescribed time you are supposed to be using Tamiflu is over 10 days, it should be refrigerated. When refrigerated, it is good for up to 17 days.

Below is an excerpt from the 'Storage and Handling' section from the prescribing information for Tamiflu that summarizes the storage conditions:

"Store constituted oral suspension under refrigeration for up to 17 days at 2℃ to 8℃ (36℉ to 46℉). Do not freeze. Alternatively, store constituted oral suspension for up to 10 days at 25℃ (77℉); excursions permitted to 15℃ to 30℃ (59℉ to 86℉)"

Compounded Tamiflu Refrigerator Requirements

A Tamiflu suspension can be compounded by your pharmacist from Tamiflu capsules if the commercially available product is undergoing a supply shortage.

There are three different liquid vehicles your pharmacist can use to make the suspension:

  • Cherry Syrup (manufactured by Humco)
  • Ora‐Sweet SF (sugar‐free) (manufactured by Paddock Laboratories)
  • Simple syrup (which is a 1:1 mixture of sugar and water)

Regardless of the liquid vehicle your pharmacist uses to make the compounded Tamiflu suspension, the prescribing information states that they are only stable at room temperature for 5 days (which is less than the 10 days for the commercially available suspension).

Per the prescribing information:

"Store the prepared oral suspension in glass or PET bottles either: In a refrigerator [2℃ to 8℃ (36° to 46°F)]: Stable for 5 weeks when stored in a refrigerator. At room temperature [25℃ (77°F)]: Stable for 5 days when stored at room temperature."

Even though the prescribing information states a 5-day expiration date for compounded Tamiflu suspension, there are numerous studies that have tested the stability of it with the various liquid vehicles amd report longer stability periods.

One of the largest studies on the matter, published in the Journal of the American Pharmacists Association, reported the following stability times for the various liquid vehicles:

  • Cherry Syrup Tamiflu Preparation: Stable for up to 35 days under refrigeration (5℃; 41℉) and up to 5 days at room temperature (25℃; 77℉)
  • Ora-Sweet SF (Sugar-Free) Preparation: Stable for up to 35 days at 5℃ (41℉) or 25℃ (77℉) and for up to 13 days at 30℃ (86℉) in either

The study didn't test the 'simple syrup' version of the preparation, but since it contains high amounts of sugar, we can assume that it has similar stability to the cherry syrup preparation (35 days under refrigeration, 5 days at room temperature).

It is important to note that even if your pharmacist used Ora-Sweet SF to make your compounded Tamiflu suspension, your prescription will likely still have a 5 days expiration date at room temperature label, even though studies say it is likely stable for a longer period of time, since that is what the manufacturer recommends in the prescribing information.

Summary Graphic

Below is an image that summarizes the recommended storage conditions from the manufacturer of Tamiflu:

Tamiflu Suspension And Compounded Tamiflu Suspension Stability At Room Temperature And Refrigeration

Answer Summary

The commercially available Tamiflu suspension is stable for 17 days under refrigeration and 10 days at room temperature. The compounded version of Tamiflu suspension is stable for 5 weeks under refrigeration and 5 days at room temperature.