Misleadingly known as black cumin, Nigella sativa has a variety of potentially active compounds, including the powerful anti-inflammatory thymoquinone,
which is also in thyme. A 2011 study showed that supplementing with this herb can reduce allergic symptoms such as congestion and itching, likely because of its ability to reduce histamine secretion, a primary driver for allergic symptoms.
A 2008 study found that taking a small amount of spirulina, a blue-green algae grown in tropical to subtropical waters, appears to greatly reduce symptoms of hay fever. High in protein as well as iron, B vitamins, and minerals, it has a long list of other health benefits, including working as an antioxidant and helping to improve heart health.
Proponents of this traditional ayurvedic medicine (also known as guduchi) say it has several immune-boosting properties. One 2005 study found it significantly decreased all symptoms of patients suffering from allergic rhinitis and increased immune cell response
in 69% of them.
A component of many herbs, including rosemary and the sedative lemon balm, rosmarinic acid is used to treat asthma, nausea, and muscle spasms. It also has antiallergic properties and is antiviral, antibacterial, anti-inflammatory, and an antioxidant. A 2005 Japanese study found that an extract of the herb Perilla frutescens enriched with rosmarinic acid significantly reduced symptoms of an itchy nose and watery and itchy eyes for those with seasonal allergic rhinoconjunctivitis.
Most of the focus on stinging nettle (also known as Urtica dioica) derives from its ability to treat urinary problems and joint pain. But researchers also believe that its stinging hairs allow the herb to act as an antihistamine by reducing levels of inflammatory chemicals. A 2009 study in Phytotherapy Research reported stinging nettle extract has compounds that may inhibit several key inflammatory pathways causing the symptoms of seasonal allergies.
“It seems to provide mild benefits and can also be ingested as a medicinal tea,” Patel says.