Possibly Effective:

(Sent by Vicky. Thank you!)
ELDERBERRY (Possibly Effective)
Influenza
Clinical research shows that some elderberry extracts might reduce flu-like symptoms. A specific syrup formulation of elderberry fruit extract (Sambucol, Nature's Way) 15 mL (1 tablespoon) 4 times daily seems to reduce the symptoms and duration of influenza infection when given within 48 hours of initial symptoms. Significant symptom relief seems to occur within 2 to 4 days of treatment for most patients. On average, this elderberry extract seems to reduce the duration of symptoms by about 56%.

NASAL IRRIGATION (Possibly Effective)
Upper respiratory tract infection (URTI)
Clinical research shows that isotonic saline nasal irrigation significantly reduces symptoms of the common cold including rhinitis, sore throat, cough, and nasal obstructor and secretion in children with the common cold or flu. Nasal irrigation also reduced the use of other medications including antipyretics, decongestants, mucolytics, and anti-infectives.

VITAMIN D (Possibly Effective)
Influenza
Some clinical research shows that taking vitamin D (cholecalciferol) 1200 IU daily during the winter significantly reduces the risk of developing seasonal flu by about 42% in school aged children compared to placebo.