What plants are anticholinergic? Identifying toxic flora

October 8, 2025 •

5 min read

Over 2,000 species of plants, many within the nightshade family, contain the potent anticholinergic compounds known as tropane alkaloids. Understanding what plants are anticholinergic is crucial, as ingestion of these can lead to severe, and sometimes fatal, toxicity.

Quick Summary

Numerous plants, particularly in the Solanaceae family, contain powerful anticholinergic agents called tropane alkaloids. Species like deadly nightshade, jimsonweed, and henbane can cause a toxic syndrome characterized by severe neurological and systemic effects upon ingestion.

Key Points

Nightshade Family: Most anticholinergic plants, including deadly nightshade and jimson weed, belong to the Solanaceae or nightshade family.
Tropane Alkaloids: The toxic effects are caused by tropane alkaloids, primarily atropine, scopolamine, and hyoscyamine, which block acetylcholine receptors.
Varied Potency: The concentration of toxic alkaloids can vary significantly depending on the plant species, its age, and the part of the plant consumed.
Symptom Recognition: The anticholinergic toxidrome includes symptoms like dilated pupils, dry mouth, rapid heartbeat, fever, confusion, and hallucinations.
Accidental Poisoning Risk: Sweet-tasting berries of plants like deadly nightshade are especially dangerous to children who might mistake them for edible fruit.
Treatment is Critical: In cases of severe poisoning, supportive care and an antidote like physostigmine are required, emphasizing the need for immediate medical intervention.

The Nightshade Family: A Source of Anticholinergics

The majority of plants with significant anticholinergic properties belong to the nightshade family, known scientifically as Solanaceae. This diverse family includes both familiar food staples, such as tomatoes and potatoes, and highly toxic ornamental and wild species. The danger lies in the concentration and type of alkaloids, which can vary dramatically between species and even different parts of the same plant. The primary compounds responsible for the anticholinergic effects are tropane alkaloids, including atropine, scopolamine, and hyoscyamine. These compounds competitively block muscarinic acetylcholine receptors, which regulate numerous involuntary bodily functions.

Prominent Anticholinergic Plants

Many of these toxic plants are found worldwide, and their potent effects have been recognized for centuries. Identifying them is the first step in prevention.

Deadly Nightshade (Atropa belladonna)

Arguably one of the most famous poisonous plants, deadly nightshade is native to Europe and Western Asia and has been introduced to parts of North America. All parts of the plant are extremely toxic, particularly the sweet-tasting, black berries, which pose a significant risk to children. The foliage contains high levels of the alkaloids atropine, scopolamine, and hyoscyamine. Historically, the berries' juice was used by women to dilate their pupils, a practice that inspired the plant's Latin name, 'beautiful lady'.

Jimson Weed (Datura stramonium)

Also known as thorn apple, devil's weed, or stinkweed, jimson weed is an aggressive invasive plant found in temperate and tropical regions globally. All parts of the plant contain high levels of tropane alkaloids, with the leaves and seeds having the highest concentrations. Ingestion, smoking, or brewing of the plant can cause severe anticholinergic syndrome, often including profound disorientation, amnesia, and terrifying hallucinations. Recreational use has led to numerous hospitalizations and, in some cases, death.

Henbane (Hyoscyamus niger)

Black henbane is a foul-smelling plant native to Eurasia but now widely distributed. It produces scopolamine and atropine, which have historically been used for both medicinal purposes and as a poison. The anticholinergic effects cause sedation, hallucinations, and delirium. In ancient times, extracts of henbane and other nightshades were absorbed transdermally via ointments, reportedly leading to feelings of flying.

Angel's Trumpet (Brugmansia species)

These large, ornamental shrubs are recognizable by their distinctive trumpet-shaped, drooping flowers. All parts of the plant are poisonous, particularly the seeds and leaves, and contain high levels of scopolamine and atropine. Intentional ingestion for hallucinogenic effects has resulted in severe anticholinergic toxicity, with some users reporting unpleasant, terrifying hallucinations.

Mandrake (Mandragora officinarum)

Native to the Mediterranean, mandrake is a solanaceous plant with a thick, often forked root that has long been associated with folklore and magic. It contains anticholinergic tropane alkaloids and can cause severe atropine-like poisoning. Accidental intoxication has occurred when the plant was mistaken for edible vegetables like chard or spinach.

The Mechanism of Anticholinergic Action

Anticholinergic plants exert their effects by blocking the action of acetylcholine, a key neurotransmitter in both the central and peripheral nervous systems. The tropane alkaloids act as competitive antagonists at muscarinic acetylcholine receptors. This blockade disrupts the parasympathetic nervous system's ability to regulate involuntary activities, leading to the characteristic constellation of symptoms known as the anticholinergic toxidrome. Since the alkaloids (especially scopolamine) can cross the blood-brain barrier, they also cause central nervous system effects like hallucinations and delirium.

Anticholinergic Toxidrome Symptoms

Ingestion of anticholinergic plants can result in a predictable set of symptoms. The classic mnemonic for anticholinergic syndrome is "blind as a bat, dry as a bone, red as a beet, mad as a hatter, and hot as a hare".

Common symptoms include:

Blind as a bat: Dilated pupils (mydriasis) leading to blurred vision and sensitivity to light.
Dry as a bone: Extremely dry mouth and throat, decreased sweating.
Red as a beet: Flushed, hot, and dry skin.
Mad as a hatter: Confusion, delirium, agitation, and hallucinations.
Hot as a hare: High body temperature (hyperthermia) due to lack of sweating.
Other effects: Rapid heart rate (tachycardia), urinary retention, and constipation or ileus.

Comparison of Key Anticholinergic Plants


Feature	Deadly Nightshade	Jimson Weed	Henbane	Angel's Trumpet
Botanical Name	Atropa belladonna	Datura stramonium	Hyoscyamus niger	Brugmansia species
Key Alkaloids	Atropine, Scopolamine, Hyoscyamine	Atropine, Scopolamine, Hyoscyamine	Scopolamine, Hyoscyamine	Scopolamine, Atropine
Toxic Parts	All parts, especially berries and roots	All parts, seeds and leaves highly toxic	All parts, including leaves and seeds	All parts, seeds and leaves particularly dangerous
Distinguishing Feature	Glossy, purple-black berries	Large, spiny fruit (thorn apple)	Sticky, hairy leaves and unpleasant odor	Large, pendulous, trumpet-shaped flowers
Primary Effect	Delirium, hallucinations, risk to children	Intense hallucinations, amnesia, delirium	Sedation, delirium, sometimes used historically for rituals	Terrifying hallucinations, severe anticholinergic toxidrome
Geographic Range	Native to Europe, parts of Asia; naturalized elsewhere	Found worldwide in temperate and tropical areas	Native to Eurasia; widely distributed	Native to South America; cultivated as an ornamental

Other Anticholinergic and Related Plants

While the nightshade family is the most notorious source, trace amounts of anticholinergic compounds have been noted in other plants. It is important to note that most food crops in the nightshade family, such as tomatoes, potatoes, and eggplants, contain only trace amounts of alkaloids in their unripe stages and are not considered a significant risk. Other related genera, including Duboisia and Solandra, also contain tropane alkaloids.

Precautions and Dangers

The most significant risk associated with anticholinergic plants comes from accidental ingestion, often by children mistaking berries for edible fruit, or deliberate misuse by adolescents seeking hallucinogenic effects. Symptoms can begin within 30 to 60 minutes after ingestion and can last for 24 to 48 hours, or even longer in severe cases. Treatment typically involves supportive care and, in severe cases, the administration of an antidote like physostigmine, which reverses both the central and peripheral effects. For comprehensive information on plant poisoning, resources like the California Poison Control System offer valuable guidance.

Conclusion

In summary, a variety of plants, predominantly from the nightshade family, are anticholinergic due to their tropane alkaloid content. Species like deadly nightshade, jimson weed, henbane, and angel's trumpet pose a significant toxic risk and should be recognized and avoided. The potent effects of these plants on the nervous system underscore the importance of public awareness and proper identification to prevent dangerous, and potentially fatal, poisonings. If ingestion is suspected, immediate medical attention is necessary due to the severity of the anticholinergic toxidrome.

Frequently Asked Questions

An anticholinergic plant contains alkaloids that block the neurotransmitter acetylcholine at muscarinic receptors throughout the body. This interference disrupts the parasympathetic nervous system, leading to a wide range of toxic effects.

Generally, yes. While the concentration of alkaloids varies, all parts of a poisonous anticholinergic plant are considered toxic. In some species, like deadly nightshade, the berries are particularly dangerous, while in others, the leaves or roots may be more potent.

Initial symptoms often include hallucinations, dry mouth, thirst, dilated pupils, blurred vision, and difficulty speaking or swallowing. These typically appear within an hour of ingestion.

Yes, many common foods like tomatoes and potatoes belong to the nightshade family. However, they contain only trace amounts of tropane alkaloids and are not considered a toxic risk when ripe. Toxicity is primarily associated with specific wild and ornamental species.

Treatment involves supportive care, such as cardiac monitoring and hydration. For severe cases, an antidote like physostigmine may be administered to reverse the central and peripheral effects.

Yes, the alkaloids derived from these plants have therapeutic uses. For example, atropine and scopolamine are used in medications for issues ranging from slow heart rate to motion sickness. However, this is done under controlled medical supervision and with synthetic versions of the compounds.

While both are muscarinic receptor antagonists, scopolamine more readily crosses the blood-brain barrier than atropine, leading to stronger central nervous system effects such as sedation, memory impairment, and hallucinations.

No, they are distinct plants, though both are in the nightshade family and contain similar anticholinergic compounds. Angel's Trumpet (Brugmansia) is a large shrub with pendulous flowers, while Jimson Weed (Datura) is typically a smaller, bushy annual with upward-pointing flowers.