Materia Medica

Lobelia inflata, Campanulaceae.  The common names include lobelia, pukeweed and Indian tobacco.

Lobelia has traditional use by Native Americans and was introduced into Western medicine in 1807.  It was popularized by Samuel Thomson and was used extensively by the Eclectic physicians.  It was a popular herb in the nineteenth century in both North America and England, used as an emetic, antispasmodic, asthma treatment and childbirth aid.

 During the sociological warfare that ensued between practitioners of medicine in the nineteenth century, lobelia became a symbol.  The herbalists considered it a harmless herb of great therapeutic value while their competitors of the Regular school of medicine considered it a deadly poison.  The misinformation of those times has been passed on and the toxicity of lobelia is still under debate to this day.  A thorough and extensive research into this matter has found that there are  no deaths that have been caused by lobelia, and that much the negative information has been passed down uncritically.¹

Lobelia is native to the United States and is a hardy annual that is partially parasitic on the roots of other plants.  It has an erect stem, up to two feet tall with alternate, ovate-oblong leaves.  The flowers are blue and on racemes.

The entire above ground plant, including seeds are the parts used.  It is available as bulk herb, capsules, hydroalcoholic extracts, and vinegar extracts.

Lobelia contains pyridine alkaloids composed mainly of lobeline, with lesser amounts of lobelanine, lobelanidine and others.  Lobeline has many of the same pharmacological actions as nicotine, but less potent.  This has led to its use as a tobacco smoking deterrent.²

Lobelia has a traditional use of being an expectorant and being used for asthma and bronchitis.   Experiments have shown it to be a bronchoconstrictor for dogs and rats, but a brochodilator with guinea pigs (and presumably humans). ³  It appears to have a cholinergic effect on the respiratory system, and as it binds to nicotine acetylcholine receptors in ganglions it promotes the release of epinephrine and norepinephrine.  Its major actions appear to be mediated by the adrenal cortex.  Lobeline also is a cardiovascular stimulant with a sympathetic alpha adrenergic hypertensive effect.⁴

It is reported to case a slight but definite suppression of appetite. Studies have shown it to inhibit intestinal motility.⁵  It has a definite emetic effect which is mediated by its stimulation of the emetic chemoreceptor trigger zone in the area postrema of the medulla oblongata and activation of vagal and spinal afferent nerves that form the sensory input of the reflex pathways involved in vomiting. 

Studies have shown Lobelia to have an antidepressant effect, related to the constituent beta-amyrin palmitate.  Beta-amyrin palmitate stimulates norepinephrine, which appears to be the mechanism of action.⁶ 

Lobelia is a systemic relaxant with a general depressant action the central and autonomic nervous systems and on neuro-muscular action.  There is a paradoxical effect of both stimulation and relaxation, particularly of the respiratory system.  Lobeline is a stimulant while isolobelanine is a relaxant.⁷

Lobelia is used as a respiratory stimulant, anti-asthmatic, expectorant, emetic and an anti-spasmodic.  It is also used as a deterrent to tobacco smoking.  The PDR for Herbal Medicine states that it is no longer in use except homeopathically, while in fact in actual practice it is a fairly popular herb.

Pyridine alkaloids are the primary active constituent, lobeline accounting for 20 to 25% of the total.  The content of lobeline diminishes with the age of the plant from 1.95% in the juvenile to 1.46%in the adolescent to .76% in the mature plant, and also varies in the parts of the plant.⁸  It contains at least 30 other alkaloids including:  8-10-diethyl lobelidiol, 8-ethyl norlobelol-1, isolobinanidine, isolobinine, lelobanidines 1, 11, lobelanidine, lobelanine, lobinalidine, lobinaline, lobinanidine, lobinine, 8-methyl-10-ethyl-lobelidiol, 8-methyl-10-phenyl-lobelidiol, norlelobanidine, norlobelanidine and norlobelanine.⁹  It also contains beta-amyrin palmitate, chelidonic acid, caoutchouc, resins, gums, wax, lipids and inflatin.

An infusion is made with one cup of boiling water and ¼ to ½ teaspoon of the dried herb, taken three times a day.  The liquid extract, 5 to 30 drops, taken three times a day.  Lobelia should not be used during pregnancy,  with tobacco sensitivity, high blood pressure, pneumonia or fluid around the lungs, dyspnea from chronic heart disease.¹⁰

Ingestion of too much lobelia usually results in vomiting, lessening the likelihood of an overdose.  The toxic symptoms are like nicotine poisoning which includes nausea, salivation, diarrhea, disturbed hearing and vision, mental confusion and marked weakness.  In theory, death could result from respiratory failure.