Nigella seed (Nigella sativa), also known as black seed or black cumin, has been traditionally used in various cultures for a range of ailments, including respiratory issues. More recently, there has been a growing body of scientific research exploring its potential anti-allergic and anti-inflammatory effects, particularly in relation to respiratory allergies such as allergic rhinitis and asthma.

Several clinical studies have evaluated the effects of Nigella sativa on allergic symptoms. For example, a double-blind, randomized, placebo-controlled trial published in Phytotherapy Research (2013) found that supplementation with Nigella sativa oil significantly reduced symptoms of allergic rhinitis compared to placebo. Other studies, including a trial published in Annals of Saudi Medicine (2003), demonstrated improvements in asthma symptoms and pulmonary function in patients using Nigella sativa extract.

The proposed mechanisms for these benefits include inhibition of histamine release, modulation of immune responses (such as balancing Th1/Th2 cytokines), and antioxidant effects. The active constituent thymoquinone is thought to play a key role in these activities.

While these results are promising, the number of high-quality human trials remains limited, and sample sizes have generally been small. Thus, although there is scientific evidence supporting the use of Nigella seed for respiratory allergies, further large-scale studies are needed to strengthen these findings and determine optimal dosing and safety.