How Long Does It Take To Recover From Viral Fever?

my wife suffering from fever since last 8 days. Fever going upto 101F. she is talking tylenol ( extra strength)and Motrin, 2 tablet each, alternatively every six hours. fever starts rising after every 4-5 hours.Her flu test, soar throat test have come negative, chest x-ray clear.How long the viral fever can last? What is your advice?
Ramesh Saini
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