Don’t Count on These
The Database cites insufficient evidence for the use of stinging nettle, echinacea, vitamin C, capsaicin, cat’s claw, goldenseal, MSM, quercetin and spirulina for treating allergic rhinitis; it is even less enthusiastic about grape seed extract. Other sources have a more favorable view of some of these remedies, including spirulina, quercetin and grape seed extract, citing some evidence of effectiveness—though still not enough to recommend them.