Quercetin is a bioflavonoid found in onions, apples, black tea, and grapefruit. Quercetin has antiallergic, antioxidant, and anti-inflammatory activity. Mast cells contribute to the inflammatory process in allergic reactions, where immunologic stimulation leads to degranulation of the mast cell, as well as to the generation of numerous cytokines and inflammatory mediators. Quercetin is an effective treatment option for allergies, as it has been shown to inhibit mast-cell secretions and has the ability to downregulate histamine production via inhibition of the enzyme histidine decarboxylase (HDC) mRNA from human mast cells. Quercetin also causes a decrease in the release of IL-6 and tryptase, and is known to inhibit phospholipase A2 and 5-lipoxygenase, thereby reducing synthesis of leukotrienes and the series-2 prostaglandins via the arachidonic–acid pathway. The anti-inflammatory properties of quercetin were explored in a double-blind, placebo-controlled study on men with chronic prostatitis syndromes. The study found that after one month of treatment, 67% of men in the treatment group reported at least a 25% improvement in their pain levels.

Bromelain is a proteolytic enzyme derived from the stem of the pineapple plant. Bromelain has been found to be a mucolytic agent effective in respiratory disorders, and functions as an anti-inflammatory agent. Bromelain counteracts the fibrin and kinin pathways, which stimulate plasmin. Plasmin blocks endogenous arachidonic-acid mobilization and reduces prostaglandin synthesis, which reduces localized inflammation and edema. This is thought to be the mechanism by which bromelain helps reduce symptoms of allergic rhinitis. Bromelain may also enhance the effectiveness of quercetin.