1st who told you to use Mahalaxmi Vilas Ras.
2nd which one, it's classical reference are also different
if it is prescribed it's okay. But if you are taking it of your own you it's really not good.
3rd What sort of respiratory tract infection you have, again not mentioned.
Next Steps
Consult your Ayurveda Physician Now. Don't take any medication randomly by deciding things your self. Every system of medicine work on its own principle. Let the professional decide what medicine you should take.
Health Tips
When you seek help ask with complete information. Educate yourself completely half knowledge is always dangerous.