Antiviral Therapy in Patients With Influenza

Marie Welch, PharmD; Casey Mabus, PharmD; John A. (Jake) Galdo, PharmD, BCPS, BCGP


US Pharmacist. 2017;42(4):32-36. 

In This Article

Clinical Course

The symptoms associated with the influenza virus resemble those of bacterial infections and the common cold; the differential diagnosis is an important consideration in caring for patients. Unlike the common cold, influenza symptoms are usually abrupt, with the first signs being a quick-onset fever (100–104°F) and cough.[14] The cough is usually dry and severe, causing chest discomfort. Other symptoms include severe myalgia, arthralgia, fatigue, malaise, decreased appetite, and headache. Nasal congestion, sneezing, and sore throat are more prevalent in patients with the common cold, and influenza's severe dry cough and fatigue typically instigate treatment.[14]

For influenzas A and B, diagnosis is usually made with a nasopharyngeal or nasal swab. Rapid influenza diagnostic tests (RIDTs) detect viral antigens and are among the most commonly used diagnostic tools because results are available rapidly (<15 minutes). However, the test's sensitivity of 50% to 70% leads to many false-negatives, and specimens used for RIDTs should be collected within 3 to 4 days (or sooner) of symptom onset.[15,16]

The reverse transcription polymerase chain reaction (RT-PCR) test remains the gold standard for influenza diagnosis because of its high specificity and sensitivity.[16] In addition to nasopharyngeal swabs, several specimens—including throat swabs, bronchial wash, and sputum—may be used. Samples from the lower respiratory tract can detect a positive diagnosis after 4 days post symptom onset; however, it may take 1 to 8 hours to get results.[15]

Once influenza is diagnosed, nonpharmacologic and pharmacologic treatment options should be considered to manage symptoms and decrease the duration and severity of the virus.