Using acetaminophen to treat the flu may not help improve symptoms, despite guidelines suggesting use of the anti-fever drug to treat the virus, a new study shows.

The study found patients with the flu who received four daily doses of acetaminophen had no signs of reduced flu levels and no difference in other clinical symptoms compared to patients who received a placebo. Patients on acetaminophen also showed no decrease in fever, despite the drug’s anti-fever properties.

Reducing fever — one of the body’s adaptive responses to infection — during the flu could actually exacerbate flu symptoms by allowing virus levels to stay higher for longer, researchers noted.

Acetaminophen’s lack of effect on the flu virus directly contradicts several international guidelines which suggest taking the drug to combat flu symptoms. Results of the study, which were conducted by the Medical Research Institute of New Zealand, appear in Respirology.