Brief Answer:
it depends...

Detailed Answer:
Hello,

there is no such thing as a "best" drug. The choice depends on the diagnosis and patient's history. Doxycycline is a broad spectrum drug that works for most patients and most respiratory tract infections but it's not the best drug for every patient or every diagnosis. For example patients with COPD can be prescribed quinolones. Quinolones are not the most appropriate choice for patients without serious medical history though.

The diagnosis is another factor the doctor has to take into account. Pneumonia is a more serious disease than pharyngitis or a simple upper respiratory tract infection.

If you've got pneumonia then the best choice depends on its severity. For example pneumonia with more than one focus of infection requires hospital treatment with intravenous drugs, tuberculosis requires special treatment, risk for resistant pathogen requires hospital admission, etc.

Common community pneumonias can be treated with drugs like doxycycline. Sometimes it may take 4-5 days to see substantial improvement. If there is no improvement then reassessment is required first.

Regarding nebulized drugs, it also depends on the patient's history. A patient with COPD would require a b2-bronchodilator like salbutamol and ipratropium. Corticosteroid treatment may help sometimes.

Can you please provide more information about your medical history and current condition? Have you done any tests? An X-ray? Oxygen saturation? Anything else?

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