Well im no expert here... but flu is basically 90% of times an allergic reaction, it gets triggered due to ur sensitivity to an allergen.
Arinac is an effective tablet but again works for a limited time. It has an anti allergy agent in it too thats why its effective. Likewise any anti allergy pill like piriton, zyrtec etc is helpful.
The key to treating flu is.. take an anti allergy pill as soon as u feel flu is started, its triggering and ur body is reacting to an allergen.
Once u delay taking anti allergy, then the pill only works for a limited time as a relief from runny nose etc but flu would settle on its own with time.
Immediately taking anti allergy ensures that u dont get congestion and clogged nose. It get settled quickly.