Complementary therapies such as herbal medicine, acupuncture and yoga can reduce asthma severity, often allowing patients to reduce dosages or eliminate the need for pharmaceuticals. Asthma sufferers, however, should not stop taking their medications or substitute herbs for them. Rather, they should make changes to their treatment regimen under the supervision of a qualified medical practitioner.
That said, these herbs have either years of traditional use or clinical trials showing they can help people regain respiratory health.
Ginkgo (Ginkgo biloba) has long been used by the Chinese to treat asthma. The leaves contain ginkgolides, which inhibit platelet activating factor, a chemical that mediates asthma and allergies. Small, placebo-
controlled trials show that oral, but not inhaled, ginkgolides (in a formulation called BN52063) significantly reduce bronchoconstriction in response to inhaled allergens  and partially protect against exercise-induced bronchoconstriction. 
Coffee and tea both contain caffeine, which is chemically related to the asthma drug theophylline. A placebo-controlled trial of 13 asthmatics found that 7 mg caffeine per kg of body weight significantly improved baseline lung function and prevented exercise-induced bronchospasm.  Coffee has 135 to 150 mg of caffeine per eight-ounce cup; tea has about 60 mg.
Onion (Allium cepa) has long been used to treat bronchitis and asthma. Lab tests showthat onion extracts can block the enzymes that produce chemicals of inflammation such as thromboxane A2, and inhibit allergen-induced asthmatic responses.  The active ingredients in onion include isothiocyanates, thiosulfinates and the bioflavonoid quercetin.
Licorice (Glycyrrhiza glabra) is an antiviral, expectorant, demulcent, anti-inflammatory and immune stimulantall properties of potential benefit for asthma sufferers. Licorice slows the breakdown of corticosteroids, thus prolonging the anti-inflammatory effects of hormones such as cortisol.  Clients should not add licorice to glucocorticoid treatment unless they are under the supervision of a physician who can adjust their drug dosage. When taken continuously for several weeks, licorice can cause sodium and water retention as well as potassium loss, resulting in elevated blood pressure. Therefore, it is not recommended for people with hypertension. There are other contraindications necessitating that its use be monitored.
Ephedra (Ephedra sinica), or Ma huang, has a 5,000-year history of use in Chinese medicine as an asthma treatment.  One of its active constituents is ephedrine, which is similar in structure to the epinephrine (adrenaline) produced in the body. Actions include bronchodilation and decongestion. Too much ephedra will cause undesirable stimulatory effects such as restlessness, anxiety, tremors, insomnia, headaches and elevated blood pressure and heart rate. Modern beta-adrenergic bronchodilators act in a more specific way, reducing many of these side effects and offering patients a safe and effective treatment.
When used appropriately and under medical supervision, ephedra can safely provide some asthma sufferers relief. Ephedra is not recommended for people with high blood pressure, heart disease, glaucoma, anorexia, hyperthyroidism, diabetes, or for pregnant or lactating women. People on theophylline or monoamine oxidase inhibitors should not take this herb.
Turmeric (Curcuma longa) contains curcumin, which has anti-inflammatory, antiviral, antioxidant and anti-tumor activity. In vitro studies show that curcumin blocks the allergen-
triggered release of inflammatory chemicals in white blood cells taken from asthma patients. [7 ]Although clinical trials have yet to prove so, in vitro studies suggest that curcumin could help control allergic diseases such as asthma.
Other supportive herbs asthmatics may want to discuss with an herbalist or health care provider are astragalus (Astragalus membranaceus), an immune tonic; echinacea (Echinacea purpurea, E. pallida), an immune stimulant; elecampane (Inula helenium) an antiseptic and expectorant; marshmallow (Althaea officinalis), a demulcent and immune stimulant; mullein (Verbascum thapsus), an antispasmodic and anti-inflammatory; nettles (Urtica dioica), an antihistamine; and rosemary (Rosmarinus officinalis), whose volatile oils have been shown to relax tracheal smooth muscle,  which theoretically may block bronchoconstriction.
1. Ginot P. Effect of BN52063, a specific PAF-acether antagonist, on bronchial provocation test to allergens in asthmatic patients. Prostaglandins 1987;34:723-31.
2. wilkens JH, et al. Effects of a PAF-antagonist (BN52063) on bronchoconstriction and platelet activation during exercise-induced asthma. Brit J Pharmacol 1990;29:85-91.
3. Kivity S, et al. The effect of caffeine on exercise-induced bronchoconstriction. Chest 1990;97:1083-5.
4. Dorsch W, Wagner h. Newantiasthmatic drugs from traditional medicine? Int Arch Allergy Appl Immunol 1991;94(1-4):262-5.
5. Homma M, et al. A novel 11-beta-hydroxysteroid dehydrogenase inhibitor contained in Saiboku-To, an herbal remedy for steroid-dependent bronchial asthma. J Pharmacy and Pharmacol 1994;46:305-9.
6. Goodman LS, Gilman A. The pharmacological basis of therapeutics. 5th ed. NewYork: Macmillan; 1975:500-7.
7. Kobyashi T, et al. Curcumin inhibition of dermatophagoides farinea-induced interleukin-5 and granulocyte macrophage-colony stimulating factor production by lymphocytes from bronchial asthmatics. Biochemical Pharmacol 1997;45:819-21.
8. Agel MB. Relaxant effect of the volatile oil of Rosmarinus officinalis on tracheal smooth muscle. J Ethnopharmacol 1991:33;57-62.