What is Lobelia and Why is it Used?
Lobelia, scientifically known as Lobelia inflata, is an herb native to eastern North America commonly called Indian tobacco, pukeweed, or asthma weed. Historically, Native Americans smoked it and used it for respiratory ailments. In the 18th and 19th centuries, it was adopted into medical practice primarily to induce vomiting (emesis) and treat conditions like asthma and colic.
The primary active compound in lobelia is the piperidine alkaloid lobeline. Lobeline has effects on the body that are similar to nicotine, which led to its use in over-the-counter products for smoking cessation. However, in 1993, the U.S. Food and Drug Administration (FDA) prohibited the sale of these products due to a lack of evidence for their effectiveness and safety. Despite this, lobelia is still available in various forms, including tinctures (drops), capsules, and dried herbs.
The Mechanism Behind the Effects
The main active ingredient, lobeline, acts on nicotinic acetylcholine receptors in the body, similar to nicotine, but it is not as potent. It functions as both an agonist (activator) and antagonist (blocker) at these receptors. This dual action initially causes stimulation of the central nervous system, which is then followed by depression, including severe respiratory depression. This complex mechanism is responsible for both its traditionally perceived therapeutic effects and its significant toxicity.
A Spectrum of Side Effects: From Mild to Severe
Using lobelia drops is considered LIKELY UNSAFE for most people when taken by mouth. The side effects can be unpredictable and dose-dependent, with a very small margin between a therapeutic dose and a toxic one. More than 1 ml of a tincture at one time is likely to cause nausea.
Common Side Effects
Even at lower doses, users may experience a range of uncomfortable side effects. These are often the body's first warning signs.
- Nausea and vomiting (the reason for its name 'pukeweed')
- Diarrhea
- Coughing
- Dizziness
- Tremors
- Profuse sweating
Severe and Toxic Side Effects
Larger doses of lobelia can lead to severe poisoning and life-threatening conditions. Doses of 0.6 to 1 gram of the leaf are considered toxic. Symptoms of an overdose are a medical emergency and can include:
- Rapid heartbeat (tachycardia)
- Very low blood pressure (hypotension)
- Convulsions or seizures
- Mental confusion
- Hypothermia (low body temperature)
- Respiratory depression and difficulty breathing
- Coma
Comparison: Lobeline vs. Nicotine
While lobeline is often compared to nicotine, there are critical differences in their action and safety profile.
| Feature | Lobeline (from Lobelia) | Nicotine |
|---|---|---|
| Source | Lobelia inflata plant | Tobacco plant |
| Mechanism | Partial agonist-antagonist at nicotinic receptors | Full agonist at nicotinic receptors |
| Primary Effect | Emetic; initial CNS stimulation followed by depression | Primarily a CNS stimulant |
| FDA Status | Banned in OTC smoking cessation aids since 1993 | Approved in various Nicotine Replacement Therapies (NRTs) |
| Toxicity | High; narrow margin between therapeutic and toxic dose. | High; can be fatal in overdose, but NRT dosages are controlled. |
High-Risk Groups and Contraindications
Certain individuals are at an even higher risk of adverse effects and should avoid lobelia entirely.
- Pregnant and breastfeeding women: Lobelia is LIKELY UNSAFE and can cause vomiting and potentially harm the fetus.
- Individuals with heart disease: The herb can negatively affect the heart, causing changes in heart rate and blood pressure.
- People with gastrointestinal issues: Those with ulcers, Crohn's disease, or other inflammatory bowel conditions should avoid it as it can irritate the GI tract.
- Patients with liver or kidney disease: These conditions may impair the body's ability to process the toxic alkaloids.
- Anyone with a seizure disorder, high blood pressure, or shortness of breath should not take lobelia.
Potential Drug Interactions
While not well-documented in all cases, the pharmacology of lobeline suggests potential interactions with several types of medications. Caution is advised when taking lobelia with:
- Nicotine and nicotine substitutes: May lead to an additive and unpredictable effect.
- Psychiatric medications: Including stimulants, anti-anxiety drugs, and antidepressants.
- Lithium: Lobelia may act as a diuretic, affecting how the body clears lithium and increasing the risk of serious side effects.
- Chantix (varenicline): As this medication also affects dopamine levels, there could be an interaction.
Conclusion: A Cautionary Note on Lobelia Drops
The historical use of lobelia does not override the modern understanding of its significant risks. The active compound, lobeline, is a potent alkaloid with a narrow safety margin. Side effects are common, and the risk of severe toxicity, including convulsions and coma, is very real, especially with incorrect dosing. The FDA has banned its use in smoking cessation products for good reason: a lack of proven efficacy and clear safety concerns. Given the availability of safer, more effective, and regulated alternatives for conditions like asthma or smoking cessation, the use of lobelia drops is not recommended. Always consult a healthcare provider before considering any herbal supplement, especially one as potent and potentially dangerous as lobelia.
Disclaimer: This article is for informational purposes only and does not constitute medical advice. The use of lobelia is not recommended due to its potential for severe toxicity. Always consult with a qualified healthcare professional before using any herbal product. For more information on supplement safety, you can visit the National Center for Complementary and Integrative Health (NCCIH).
