influenza
"My 6 yr old son began having flu symptoms on a Saturday afternoon after having been exposed to the flu earlier in the week. He began taking Tamiflu Saturday evening. That Sunday he had a low grade fever most of the day and felt achy and rundown but was still active. By Monday he no longer had a fever, was eating normally and it was as if nothing had ever happened. He said that it tasted bad but he did not experience any unpleasant side effects."