Massage the oil or balms directly on the chest, neck, and sinus area during cold-flu-allergy- congestion. Repeat as needed.
Recommended of course to use in conjunction with drinking lots of fluids - teas, broths, water, increasing nutrition especially with immune supporters like garlic, avoiding dairy products as those tend to gunk things up, take the rest!
Combine with drinking Mullein herb, dry or fresh, alone or with other Plants, or Mullein tincture, for expectorant effect, if indicated by wet cough. If cough is dry, explore more moistening herbs like Calendula, Marshmallow, Slippery Elm.