My son is on Oseltamivir. Why is he still feeling weak?

Question

Hello doctor,

My son is 19 and came down with a fever, chills, a sore throat, and body pain two days ago. His temperature was 101.6, and he has been sleeping a lot.

We tested him for COVID, and it was negative. The doctor said it is the flu and started Oseltamivir 75 mg twice a day.

He is still feeling very weak and complains of back pain. How long does flu usually take to recover fully in young adults?

His CBC showed a WBC count of 11,200 with a lymphocyte predominance. Is that expected with flu, or should we monitor for something else?

Kindly help.

Answer 1

Hello,

Welcome to icliniq.com.

I read your query and can understand your concern.

Your son is experiencing a fairly typical course of influenza, which can be particularly severe in young adults.

The flu usually comes on suddenly with high fever, chills, sore throat, muscle aches, and profound fatigue, just as your son is experiencing.

With antiviral treatment like Oseltamivir started early, most people begin to feel somewhat better within three to five days, although full recovery can still take up to a week or more.

It is not uncommon for weakness, low energy, and lingering aches, such as his back pain, to persist even after the fever subsides. Extra sleep is the body’s way of recovering.

As for the CBC (complete blood count), a white blood cell count of 11,200 with a predominance of lymphocytes is actually quite consistent with viral infections like influenza.

Bacterial infections tend to show a higher neutrophil count, so the pattern you are seeing does not raise red flags on its own.

However, it is still a good idea to keep an eye out for any worsening symptoms, such as shortness of breath, persistent high fever beyond five days, confusion, or signs of dehydration.

If any of those develop, he should be re-evaluated. Otherwise, continued rest, fluids, and symptom relief will help him recover soon.

I hope this helps.

Thank you and take care.

Regards.