Anticholinergics (anticholinergic agents) are substances that block the action of the

acetylcholine Acetylcholine (ACh) is an organic compound that functions in the brain and body of many types of animals (including humans) as a neurotransmitter. Its name is derived from its chemical structure: it is an ester of acetic acid and choline. Par ...

(ACh)

neurotransmitter A neurotransmitter is a signaling molecule secreted by a neuron to affect another cell across a Chemical synapse, synapse. The cell receiving the signal, or target cell, may be another neuron, but could also be a gland or muscle cell. Neurotra ...

synapse In the nervous system, a synapse is a structure that allows a neuron (or nerve cell) to pass an electrical or chemical signal to another neuron or a target effector cell. Synapses can be classified as either chemical or electrical, depending o ...

s in the central and

peripheral nervous system The peripheral nervous system (PNS) is one of two components that make up the nervous system of Bilateria, bilateral animals, with the other part being the central nervous system (CNS). The PNS consists of nerves and ganglia, which lie outside t ...

. These agents inhibit the

parasympathetic nervous system The parasympathetic nervous system (PSNS) is one of the three divisions of the autonomic nervous system, the others being the sympathetic nervous system and the enteric nervous system. The autonomic nervous system is responsible for regulat ...

by selectively blocking the binding of ACh to its receptor in

nerve cell A neuron (American English), neurone (British English), or nerve cell, is an excitable cell that fires electric signals called action potentials across a neural network in the nervous system. They are located in the nervous system and help to ...

s. The

nerve fiber An axon (from Greek ἄξων ''áxōn'', axis) or nerve fiber (or nerve fibre: see spelling differences) is a long, slender projection of a nerve cell, or neuron, in vertebrates, that typically conducts electrical impulses known as action pot ...

s of the parasympathetic system are responsible for the involuntary movement of smooth muscles present in the

gastrointestinal tract The gastrointestinal tract (GI tract, digestive tract, alimentary canal) is the tract or passageway of the Digestion, digestive system that leads from the mouth to the anus. The tract is the largest of the body's systems, after the cardiovascula ...

, urinary tract,

lungs The lungs are the primary organs of the respiratory system in many animals, including humans. In mammals and most other tetrapods, two lungs are located near the backbone on either side of the heart. Their function in the respiratory syste ...

sweat gland Sweat glands, also known as sudoriferous or sudoriparous glands, , are small tubular structures of the skin that produce sweat. Sweat glands are a type of exocrine gland, which are glands that produce and secrete substances onto an epithelial s ...

s, and many other parts of the body. In broad terms, anticholinergics are divided into two categories in accordance with their specific targets in the central and peripheral nervous system and at the neuromuscular junction:

antimuscarinic A muscarinic acetylcholine receptor antagonist, also simply known as a muscarinic antagonist or as an antimuscarinic agent, is a type of anticholinergic drug that blocks the activity of the muscarinic acetylcholine receptors (mAChRs). The muscarin ...

agents and antinicotinic agents ( ganglionic blockers, neuromuscular blockers). The term "anticholinergic" is typically used to refer to antimuscarinics that competitively inhibit the binding of ACh to muscarinic acetylcholine receptors; such agents do not antagonize the binding at

nicotinic acetylcholine receptor Nicotinic acetylcholine receptors, or nAChRs, are Receptor (biochemistry), receptor polypeptides that respond to the neurotransmitter acetylcholine. Nicotinic receptors also respond to drugs such as the agonist nicotine. They are found in the c ...

s at the

neuromuscular junction A neuromuscular junction (or myoneural junction) is a chemical synapse between a motor neuron and a muscle fiber. It allows the motor neuron to transmit a signal to the muscle fiber, causing muscle contraction. Muscles require innervation to ...

, although the term is sometimes used to refer to agents that do so.

Medical uses

Anticholinergic drugs are used to treat a variety of conditions: *

Dizziness Dizziness is an imprecise term that can refer to a sense of disorientation in space, vertigo, or lightheadedness. It can also refer to Balance disorder, disequilibrium or a non-specific feeling, such as giddiness or foolishness. Dizziness is a ...

(including

vertigo Vertigo is a condition in which a person has the sensation that they are moving, or that objects around them are moving, when they are not. Often it feels like a spinning or swaying movement. It may be associated with nausea, vomiting, perspira ...

and

motion sickness Motion sickness occurs due to a difference between actual and expected motion. Symptoms commonly include nausea, vomiting, cold sweat, headache, dizziness, tiredness, loss of appetite, and increased salivation. Complications may rarely include ...

-related symptoms) *

Extrapyramidal symptoms Extrapyramidal symptoms (EPS) are signs and symptoms, symptoms that are wikt:archetypical, archetypically associated with the extrapyramidal system of the brain's cerebral cortex. When such symptoms are caused by medications or other drugs, they ...

, a potential side-effect of antipsychotic medications * Gastrointestinal disorders (e.g., peptic ulcers,

diarrhea Diarrhea (American English), also spelled diarrhoea or diarrhœa (British English), is the condition of having at least three loose, liquid, or watery bowel movements in a day. It often lasts for a few days and can result in dehydration d ...

, pyloro

spasm A spasm is a sudden involuntary contraction of a muscle, a group of muscles, or a hollow organ, such as the bladder. A spasmodic muscle contraction may be caused by many medical conditions, including dystonia. Most commonly, it is a musc ...

diverticulitis Diverticulitis, also called colonic diverticulitis, is a gastrointestinal disease characterized by inflammation of abnormal pouches—Diverticulum, diverticula—that can develop in the wall of the large intestine. Symptoms typically include lo ...

ulcerative colitis Ulcerative colitis (UC) is one of the two types of inflammatory bowel disease (IBD), with the other type being Crohn's disease. It is a long-term condition that results in inflammation and ulcers of the colon and rectum. The primary sympto ...

nausea Nausea is a diffuse sensation of unease and discomfort, sometimes perceived as an urge to vomit. It can be a debilitating symptom if prolonged and has been described as placing discomfort on the chest, abdomen, or back of the throat. Over 30 d ...

, and

vomiting Vomiting (also known as emesis, puking and throwing up) is the forceful expulsion of the contents of one's stomach through the mouth and sometimes the nose. Vomiting can be the result of ailments like food poisoning, gastroenteritis, pre ...

) * Genitourinary disorders (e.g., cystitis, urethritis, and prostatitis) *

Insomnia Insomnia, also known as sleeplessness, is a sleep disorder where people have difficulty sleeping. They may have difficulty falling asleep, or staying asleep for as long as desired. Insomnia is typically followed by daytime sleepiness, low ene ...

, although usually only on a short-term basis * Respiratory disorders (e.g.,

asthma Asthma is a common long-term inflammatory disease of the airways of the lungs. It is characterized by variable and recurring symptoms, reversible airflow obstruction, and easily triggered bronchospasms. Symptoms include episodes of wh ...

chronic bronchitis Bronchitis is inflammation of the bronchi (large and medium-sized airways) in the lungs that causes coughing. Bronchitis usually begins as an infection in the nose, ears, throat, or sinuses. The infection then makes its way down to the bronchi. ...

, and

chronic obstructive pulmonary disease Chronic obstructive pulmonary disease (COPD) is a type of progressive lung disease characterized by chronic respiratory symptoms and airflow limitation. GOLD defines COPD as a heterogeneous lung condition characterized by chronic respiratory s ...

OPD * Sinus bradycardia due to a hypersensitive

vagus nerve The vagus nerve, also known as the tenth cranial nerve (CN X), plays a crucial role in the autonomic nervous system, which is responsible for regulating involuntary functions within the human body. This nerve carries both sensory and motor fibe ...

Organophosphate In organic chemistry, organophosphates (also known as phosphate esters, or OPEs) are a class of organophosphorus compounds with the general structure , a central phosphate molecule with alkyl or aromatic substituents. They can be considered ...

based

nerve agent Nerve agents, sometimes also called nerve gases, are a class of organic chemistry, organic chemicals that disrupt the mechanisms by which nerves transfer messages to organs. The disruption is caused by the blocking of acetylcholinesterase (ACh ...

poisoning Poisoning is the harmful effect which occurs when Toxicity, toxic substances are introduced into the body. The term "poisoning" is a derivative of poison, a term describing any chemical substance that may harm or kill a living organism upon ...

, such as VX, sarin, tabun, and soman (atropine is favoured in conjunction with an oxime, usually pralidoxime) Anticholinergics generally have antisialagogue effects (decreasing saliva production), and most produce some level of sedation, both being advantageous in surgical procedures. Until the beginning of the 20th century, anticholinergic drugs were widely used to treat psychiatric disorders.

Physiological effects

Effects of anticholinergic drugs include: * Delirium (often with

hallucination A hallucination is a perception in the absence of an external stimulus that has the compelling sense of reality. They are distinguishable from several related phenomena, such as dreaming ( REM sleep), which does not involve wakefulness; pse ...

s and

delusion A delusion is a fixed belief that is not amenable to change in light of conflicting evidence. As a pathology, it is distinct from a belief based on false or incomplete information, confabulation, dogma, illusion, hallucination, or some other m ...

s indistinguishable from reality) *Ocular symptoms (from eye drops):

mydriasis Mydriasis is the Pupillary dilation, dilation of the pupil, usually having a non-physiological cause, or sometimes a physiological pupillary response. Non-physiological causes of mydriasis include disease, Physical trauma, trauma, or the use of c ...

, pupil dilation, and acute angle-closure glaucoma in those with shallow anterior chamber * Anhidrosis, dry mouth, dry skin *

Fever Fever or pyrexia in humans is a symptom of an anti-infection defense mechanism that appears with Human body temperature, body temperature exceeding the normal range caused by an increase in the body's temperature Human body temperature#Fever, s ...

Constipation Constipation is a bowel dysfunction that makes bowel movements infrequent or hard to pass. The Human feces, stool is often hard and dry. Other symptoms may include abdominal pain, bloating, and feeling as if one has not completely passed the ...

Tachycardia Tachycardia, also called tachyarrhythmia, is a heart rate that exceeds the normal resting rate. In general, a resting heart rate over 100 beats per minute is accepted as tachycardia in adults. Heart rates above the resting rate may be normal ...

Urinary retention Urinary retention is an inability to completely empty the bladder. Onset can be sudden or gradual. When of sudden onset, symptoms include an inability to urinate and lower abdominal pain. When of gradual onset, symptoms may include urinary incont ...

* Cutaneous vasodilation Clinically the most significant feature is delirium, particularly in the elderly, who are most likely to be affected by the toxidrome.

Cognitive and physical decline

Long-term use may increase the risk of both cognitive and physical decline. It is unclear whether they affect the risk of death generally. However, in older adults they do appear to increase the risk of death. The anticholinergic burden (ACB) approach examines this risk.

Side effects

Possible effects of anticholinergics include: * Poor coordination *

Dementia Dementia is a syndrome associated with many neurodegenerative diseases, characterized by a general decline in cognitive abilities that affects a person's ability to perform activities of daily living, everyday activities. This typically invo ...

* Decreased mucus production in the nose and

throat In vertebrate anatomy, the throat is the front part of the neck, internally positioned in front of the vertebrae. It contains the Human pharynx, pharynx and larynx. An important section of it is the epiglottis, separating the esophagus from the t ...

; consequent dry, sore throat * Dry mouth with possible acceleration of dental caries * Cessation of sweating; consequent decreased epidermal thermal dissipation leading to warm, blotchy, or red skin * Increased

body temperature Thermoregulation is the ability of an organism to keep its body temperature within certain boundaries, even when the surrounding temperature is very different. A thermoconforming organism, by contrast, simply adopts the surrounding temperature ...

* Pupil dilation; consequent sensitivity to bright light (

photophobia Photophobia is a medical symptom of abnormal intolerance to visual perception of light. As a medical symptom, photophobia is not a morbid fear or phobia, but an experience of discomfort or pain to the eyes due to light exposure or by presence o ...

) * Loss of accommodation (loss of focusing ability, blurred vision – cycloplegia) * Double vision * Increased heart rate * Tendency to be easily startled *

* Urinary incontinence while sleeping * Diminished bowel movement, sometimes ileus (decreases motility via the

) * Increased intraocular pressure; dangerous for people with narrow-angle

glaucoma Glaucoma is a group of eye diseases that can lead to damage of the optic nerve. The optic nerve transmits visual information from the eye to the brain. Glaucoma may cause vision loss if left untreated. It has been called the "silent thief of ...

Possible effects in the

central nervous system The central nervous system (CNS) is the part of the nervous system consisting primarily of the brain, spinal cord and retina. The CNS is so named because the brain integrates the received information and coordinates and influences the activity o ...

resemble those associated with delirium, and may include: * Confusion * Disorientation * Agitation *

Euphoria Euphoria ( ) is the experience (or affect) of pleasure or excitement and intense feelings of well-being and happiness. Certain natural rewards and social activities, such as aerobic exercise, laughter, listening to or making music and da ...

dysphoria Dysphoria (; ) is a profound state of unease or dissatisfaction. It is the semantic opposite of euphoria. In a psychiatric context, dysphoria may accompany depression, anxiety, or agitation. In psychiatry Intense states of distress and uneas ...

* Respiratory depression * Memory problems * Inability to concentrate * Wandering thoughts; inability to sustain a

train of thought The train of thought or track of thought refers to the interconnection in the sequence of ideas expressed during a connected discourse or thought, as well as the sequence itself, especially in discussion how this sequence leads from one idea to ...

* Incoherent speech * Irritability * Mental confusion (brain fog) * Wakeful myoclonic jerking * Unusual sensitivity to sudden sounds * Illogical thinking *

Photophobia Photophobia is a medical symptom of abnormal intolerance to visual perception of light. As a medical symptom, photophobia is not a morbid fear or phobia, but an experience of discomfort or pain to the eyes due to light exposure or by presence o ...

* Visual disturbances ** Periodic flashes of light ** Periodic changes in visual field ** Visual snow ** Restricted or "tunnel vision" * Visual, auditory, or other sensory

s ** Warping or waving of surfaces and edges ** Textured surfaces ** "Dancing" lines; "spiders", insects; form constants ** Lifelike objects indistinguishable from reality ** Phantom smoking ** Hallucinated presence of people not actually there (e.g. shadow people) * Rarely: seizures, coma, and death * Orthostatic hypotension (severe drop in systolic blood pressure when standing up suddenly) and significantly increased risk of falls in the elderly population Older patients are at a higher risk of experiencing CNS side effects. The link possible between anticholinergic medication use and cognitive decline/dementia has been noted in weaker observational studies. Although there is no strong evidence from randomized controlled trials to suggest that these medications should be avoided, clinical guidelines suggest that a consideration be made to decrease the use of these medications if safe to do so and the use of these medications be carefully considered to reduce any possible adverse effects including cognitive decline.

Toxicity

An acute anticholinergic syndrome is reversible and subsides once all of the causative agents have been excreted. Reversible acetylcholinesterase inhibitor agents such as physostigmine can be used as an antidote in life-threatening cases. Wider use is discouraged due to the significant side effects related to cholinergic excess including seizures, muscle weakness, bradycardia, bronchoconstriction, lacrimation, salivation, bronchorrhea, vomiting, and diarrhea. Even in documented cases of anticholinergic toxicity, seizures have been reported after the rapid administration of physostigmine. Asystole has occurred after physostigmine administration for tricyclic antidepressant overdose, so a conduction delay (QRS > 0.10 second) or suggestion of tricyclic antidepressant ingestion is generally considered a contraindication to physostigmine administration.

Dementia

A recent study carried out by experts from the University of Nottingham and funded by the National Institute for Health Research (NIHR) has shown there to be an increased risk of up to 50% of patients developing Dementia due to some of these medications and cautions have been advised with their use. The study findings showed increased risks of dementia for anticholinergic drugs overall and specifically for the anticholinergic antidepressants, antipsychotic drugs, antiparkinsons drugs, bladder drugs and epilepsy drugs after accounting for other risk factors for dementia. However, in a March 2025 article published in the '' American Journal of Epidemiology'', Aguado and colleagues reported that anticholinergic antihypertensive medications reduced individuals' 10-year

risk In simple terms, risk is the possibility of something bad happening. Risk involves uncertainty about the effects/implications of an activity with respect to something that humans value (such as health, well-being, wealth, property or the environ ...

of incident

vascular dementia Vascular dementia is dementia caused by a series of strokes. Restricted blood flow due to strokes reduces oxygen and glucose delivery to the brain, causing cell injury and neurological deficits in the affected region. Subtypes of vascular dement ...

by 31% when used for ≥6 years compared to 3–6 years ( risk ratio, 0.69; 95% CI, 0.54–0.90); the comparative risk of

Alzheimer's disease Alzheimer's disease (AD) is a neurodegenerative disease and the cause of 60–70% of cases of dementia. The most common early symptom is difficulty in remembering recent events. As the disease advances, symptoms can include problems wit ...

was reduced, as well, but not to a statistically significant degree (risk ratio, 0.91; 95% CI, 0.77–1.10).

Pharmacology

Anticholinergics are classified according to the receptors that are affected: * ''

Antimuscarinic A muscarinic acetylcholine receptor antagonist, also simply known as a muscarinic antagonist or as an antimuscarinic agent, is a type of anticholinergic drug that blocks the activity of the muscarinic acetylcholine receptors (mAChRs). The muscarin ...

'' agents operate on the muscarinic acetylcholine receptors. The majority of anticholinergic drugs are antimuscarinics. * '' Antinicotinic'' agents operate on the

s. The majority of these are non-depolarising

skeletal muscle Skeletal muscle (commonly referred to as muscle) is one of the three types of vertebrate muscle tissue, the others being cardiac muscle and smooth muscle. They are part of the somatic nervous system, voluntary muscular system and typically are a ...

relaxants for surgical use that are structurally related to curare. Several are depolarizing agents.

Examples

Examples of common anticholinergics: * Antimuscarinic agents **

Antipsychotics Antipsychotics, previously known as neuroleptics and major tranquilizers, are a class of psychotropic medication primarily used to manage psychosis (including delusions, hallucinations, paranoia or disordered thought), principally in schizo ...

( clozapine, quetiapine) **

Atropine Atropine is a tropane alkaloid and anticholinergic medication used to treat certain types of nerve agent and pesticide poisonings as well as some types of slow heart rate, and to decrease saliva production during surgery. It is typically give ...

** Benztropine ** Biperiden ** Chlorpheniramine ** Certain SSRIs ( Paroxetine) ** Dicyclomine (

Dicycloverine Dicycloverine, also known as dicyclomine, sold under the brand name Bentyl among others, is a medication that is used to treat spasms of the intestines such as those that occur in irritable bowel syndrome (IBS). It is taken by mouth or by injec ...

) ** Dimenhydrinate **

Diphenhydramine Diphenhydramine, sold under the brand name Benadryl among others, is an antihistamine and sedative. Although generally considered sedating, diphenhydramine can cause paradoxical central nervous system stimulation in some individuals, particula ...

** Doxepin ** Doxylamine ** Flavoxate ** Glycopyrronium/-late ** Hyoscyamine ** Ipratropium ** Orphenadrine ** Oxitropium ** Oxybutynin ** Promethazine ** Propantheline bromide ** Scopolamine ** Solifenacin ** Tolterodine ** Tiotropium ** Tricyclic antidepressants ** Trihexyphenidyl **

Tropicamide Tropicamide, sold under the brand name Mydriacyl among others, is a medication used to dilate the pupil and help with the examination of the eye. Specifically it is used to help examine the back of the eye. It is applied as eye drops. Effect ...

** Umeclidinium * Antinicotinic agents ** Bupropion – Ganglion blocker **

Dextromethorphan Dextromethorphan, sold under the brand name Robitussin among others, is a cough suppressant used in many cough and Common cold, cold medicines. In 2022, the US Food and Drug Administration (FDA) approved the combination dextromethorphan/bupropi ...

- Cough suppressant and ganglion blocker ** Doxacurium – Nondepolarizing skeletal muscular relaxant ** Hexamethonium – Ganglion blocker ** Mecamylamine – Ganglion blocker and occasional

smoking cessation Smoking cessation, usually called quitting smoking or stopping smoking, is the process of discontinuing tobacco smoking. Tobacco smoke contains nicotine, which is Addiction, addictive and can cause Substance dependence, dependence. As a resu ...

aid ** Tubocurarine - Nondepolarizing skeletal muscular relaxant

Antidotes

Physostigmine is one of only a few drugs that can be used as an antidote for anticholinergic poisoning. Nicotine also counteracts anticholinergics by activating nicotinic acetylcholine receptors.

Caffeine Caffeine is a central nervous system (CNS) stimulant of the methylxanthine chemical classification, class and is the most commonly consumed Psychoactive drug, psychoactive substance globally. It is mainly used for its eugeroic (wakefulness pr ...

(although an

adenosine Adenosine (symbol A) is an organic compound that occurs widely in nature in the form of diverse derivatives. The molecule consists of an adenine attached to a ribose via a β-N9- glycosidic bond. Adenosine is one of the four nucleoside build ...

receptor antagonist A receptor antagonist is a type of receptor ligand or drug that blocks or dampens a biological response by binding to and blocking a receptor rather than activating it like an agonist. Antagonist drugs interfere in the natural operation of rec ...

) can counteract the anticholinergic symptoms by reducing sedation and increasing acetylcholine activity, thereby causing alertness and arousal.

Psychoactive uses

When a significant amount of an anticholinergic is taken into the body, a toxic reaction known as acute anticholinergic syndrome may result. This may happen accidentally or intentionally as a consequence of either recreational or entheogenic drug use, though many users find the side effects to be exceedingly unpleasant and not worth the recreational effects they experience. In the context of recreational use, anticholinergics are often called deliriants.

Plant sources

The most common plants containing anticholinergic alkaloids (including

atropine Atropine is a tropane alkaloid and anticholinergic medication used to treat certain types of nerve agent and pesticide poisonings as well as some types of slow heart rate, and to decrease saliva production during surgery. It is typically give ...

, scopolamine, and hyoscyamine among others) are: *'' Atropa belladonna'' (deadly nightshade) *'' Brugmansia'' species *''

Datura ''Datura'' is a genus of nine species of highly poisonous, Vespertine (biology), vespertine-flowering plants belonging to the nightshade family (Solanaceae). They are commonly known as thornapples or jimsonweeds, but are also known as devil's t ...

'' species *'' Garrya'' species *'' Hyoscyamus niger'' (henbane) *'' Mandragora officinarum'' (mandrake)

Use as a deterrent

Several narcotic and

opiate An opiate is an alkaloid substance derived from opium (or poppy straw). It differs from the similar term ''opioid'' in that the latter is used to designate all substances, both natural and synthetic, that bind to opioid receptors in the brain ( ...

-containing drug preparations, such as those containing hydrocodone and codeine are combined with an anticholinergic agent to deter intentional misuse. Examples include hydrocodone/homatropine (Tussigon, Hydromet, Hycodan), diphenoxylate/atropine (Lomotil), and hydrocodone polistirex/chlorpheniramine polistirex (Tussionex Pennkinetic, TussiCaps). However, it is noted that opioid/antihistamine combinations are used clinically for their synergistic effect in the management of pain and maintenance of dissociative

anesthesia Anesthesia (American English) or anaesthesia (British English) is a state of controlled, temporary loss of sensation or awareness that is induced for medical or veterinary purposes. It may include some or all of analgesia (relief from or prev ...

(sedation) in such preparations as meperidine/ promethazine (Mepergan) and dipipanone/ cyclizine (Diconal), which act as strong anticholinergic agents.

References

{{Authority control Medical mnemonics