Exploring What Does Belladonna Do to the Body? A Pharmacological Deep Dive

October 11, 2025 •

4 min read

Known as deadly nightshade, the Atropa belladonna plant is one of the most toxic plants in the world and contains powerful alkaloids that act as potent anticholinergics. Answering the question of what does belladonna do to the body is crucial for understanding its profound and dangerous effects, which range from pupil dilation to severe systemic poisoning.

Quick Summary

Belladonna's alkaloids, including atropine and scopolamine, act as muscarinic antagonists, blocking acetylcholine receptors in the nervous system. This causes widespread anticholinergic effects like pupil dilation, increased heart rate, and reduced secretions. In high doses, it can cause severe poisoning, hallucinations, and potentially fatal systemic complications.

Key Points

Anticholinergic Action: Belladonna’s primary effect is blocking muscarinic acetylcholine receptors, which disrupts the parasympathetic nervous system.
Nervous System Effects: High doses can cause CNS symptoms including delirium, hallucinations, confusion, seizures, and respiratory failure.
Peripheral Effects: Belladonna causes pupil dilation, dry mouth, increased heart rate, constipation, and difficulty urinating due to blocking parasympathetic signals.
Therapeutic vs. Toxic: While the plant is highly toxic, its purified alkaloids like atropine and scopolamine have controlled medical uses for conditions like IBS, motion sickness, and eye exams.
Significant Toxicity Risk: All parts of the plant are poisonous, and its toxicity is unpredictable due to varying alkaloid concentrations.
FDA Warnings: The FDA has warned against unregulated belladonna supplements, particularly those marketed for children, due to safety concerns and potential fatal consequences.

The Anticholinergic Mechanism of Action

At its core, belladonna’s effects are primarily driven by its potent anticholinergic properties. The plant contains several toxic tropane alkaloids, including atropine, scopolamine, and hyoscyamine, that competitively block muscarinic acetylcholine receptors. Acetylcholine is a key neurotransmitter in the parasympathetic nervous system, which controls many involuntary bodily functions such as digestion, salivation, and pupil constriction. By blocking these receptors, belladonna effectively inhibits the parasympathetic nerve impulses, leading to the wide-ranging and often dangerous symptoms of anticholinergic toxicity. The specific effects depend on the dose and the particular alkaloid, as some cross the blood-brain barrier more readily than others.

Impact on the Central Nervous System (CNS)

The effects of belladonna on the CNS are a key component of its toxicity and are particularly pronounced with higher doses. Scopolamine and, to a lesser extent, atropine can cross the blood-brain barrier, leading to both stimulating and depressive effects on the brain.

Central Nervous System Symptoms

Delirium and Hallucinations: Higher doses can induce vivid hallucinations, disorientation, and confusion. These can be frightening and prolonged, sometimes lasting for several days.
Psychosis and Agitation: Severe intoxication often presents with agitated delirium and psychotic symptoms due to the disruption of acetylcholine's function in learning and memory.
Memory Disruption: The blocking of muscarinic receptors can cause temporary memory loss and confusion.
Seizures and Coma: In severe cases, belladonna poisoning can lead to seizures and, eventually, a coma, respiratory failure, or cardiovascular collapse.

Effects on the Peripheral Nervous System

While the CNS effects are dramatic, belladonna's impact on the peripheral nervous system is what gives rise to many of the classic signs of poisoning. The blocking of parasympathetic signals leads to a variety of physiological changes.

Peripheral Manifestations

Eyes: The pupils dilate significantly (mydriasis), and the ciliary muscles relax, leading to blurred vision and an inability to focus on near objects (cycloplegia). This is the historical basis for the name “belladonna,” or “beautiful woman,” as Italian women once used it cosmetically.
Secretions: The reduction of salivary and sweat gland secretions results in a profoundly dry mouth and throat and dry, flushed skin. The inability to sweat properly can also lead to hyperthermia.
Heart and Circulation: Belladonna causes an increase in heart rate (tachycardia) and can elevate blood pressure. This is due to the removal of the parasympathetic braking effect on the heart.
Digestion and Urination: The relaxation of smooth muscles in the gastrointestinal tract and bladder leads to decreased bowel motility, constipation, and urinary retention.

A Historical Poison and Modern Therapeutic Agent

The history of belladonna is a paradox of both toxicity and therapeutic use. For centuries, it has been used as a poison, and in folklore, it is often associated with danger. However, its active components have been harnessed by modern medicine under strict control to treat specific conditions.

Medical Applications of Belladonna Alkaloids

Atropine: Used to dilate pupils for eye exams, treat bradycardia (slow heart rate), and as an antidote for certain types of nerve agent or pesticide poisoning.
Scopolamine: Employed to prevent motion sickness and to reduce secretions during surgery.
Hyoscyamine: Used to treat gastrointestinal disorders such as irritable bowel syndrome (IBS), spastic colon, and peptic ulcers.

Dangers of Unregulated Belladonna Products

Despite the controlled medical use of its purified alkaloids, the use of the raw Atropa belladonna plant or unregulated supplements is extremely dangerous. As few as two berries can be fatal to a small child, and the alkaloid concentration can vary unpredictably from plant to plant. The FDA has issued multiple warnings against belladonna-containing homeopathic teething products for infants due to reported seizures, respiratory problems, and death. The danger is magnified by the fact that many unregulated products are not standardized for potency, leading to a high risk of overdose.

Comparison of Belladonna Alkaloids


Feature	Atropine	Scopolamine	Hyoscyamine
CNS Effects	Can cross blood-brain barrier; CNS stimulation followed by depression in high doses; memory disruption.	Crosses blood-brain barrier more easily than atropine; stronger sedative effects; causes drowsiness.	Similar to atropine, but is the levorotatory isomer, meaning it is more potent in its peripheral effects.
Ocular Effects	Strong mydriasis (pupil dilation) and cycloplegia (loss of accommodation).	Also causes mydriasis and cycloplegia, used less frequently for this purpose.	Similar ocular effects to atropine.
Cardiovascular Effects	Strong chronotropic (heart rate-increasing) effect; used to treat bradycardia.	Less potent cardiovascular effects compared to atropine.	Also increases heart rate, similar to atropine.
Gastrointestinal Effects	Reduces gastrointestinal motility and secretions.	Reduces secretions; used for motion sickness.	Reduces GI motility and secretions, used for irritable bowel syndrome and spastic colon.
Primary Medical Use	Eye exams, bradycardia, nerve agent antidote.	Motion sickness, pre-anesthetic agent to reduce secretions.	Gastrointestinal spasms and ulcers.

Conclusion

Belladonna is a complex plant with a dual history as both a deadly poison and a source of vital medicines. Its powerful anticholinergic alkaloids—atropine, scopolamine, and hyoscyamine—interfere with the body's nervous system, leading to a wide array of effects on the eyes, heart, digestion, and brain. While its isolated and regulated components are crucial in modern pharmacology, the raw plant and its unregulated supplements are extremely dangerous and should never be consumed. The unpredictability of its toxic effects underscores the importance of public awareness and medical oversight when dealing with this notorious "deadly nightshade." Further research is continually conducted to understand its full potential and dangers, emphasizing the ongoing evolution of pharmacology.

How to Find a Reputable Pharmacist or Medical Professional

For questions about specific medications or for medical advice, always consult a qualified healthcare professional, such as a pharmacist or physician. You can find accredited professionals through national health organizations or by contacting your local hospital or clinic.

Link to FDA resource on dietary supplements

Frequently Asked Questions

Belladonna contains alkaloids like atropine that act as muscarinic antagonists, blocking receptors in the eye muscles that normally constrict the pupil. This blockage causes the pupils to dilate (mydriasis).

Yes, but not the raw plant. Purified alkaloids from belladonna, such as atropine and scopolamine, are used in controlled doses for specific medical purposes, including dilating pupils for eye exams, treating gastrointestinal spasms, and as antidotes for certain poisons.

Symptoms of belladonna poisoning include dilated pupils, blurred vision, dry mouth, flushed skin, rapid heartbeat, fever, confusion, hallucinations, and urinary retention.

The primary mechanism of action is anticholinergic, where the alkaloids block muscarinic acetylcholine receptors throughout the body, inhibiting the parasympathetic nervous system.

Yes, handling the plant can expose a person to toxins through skin absorption, which may cause irritation and severe dermatitis.

Belladonna is dangerous due to its extreme toxicity, unpredictable effects, and the potential for accidental ingestion. The concentration of toxic alkaloids can vary significantly, making overdose highly likely, especially with children or unregulated products.

Treatment for belladonna poisoning is primarily symptomatic and supportive. In severe cases, a specific antidote like physostigmine may be administered, and benzodiazepines can be used for sedation.