What Are the Effects of Anticholinergic Medications?

Anticholinergic medications work by blocking the action of the neurotransmitter acetylcholine.

A neurotransmitter is a chemical that is released by the nerve cells to send signals to other cells. Blocking the neurotransmitter acetylcholine inhibits involuntary muscle movements (muscle movements not under conscious control) in the lungs, gastrointestinal tract, urinary tract, and other areas of the body. Because anticholinergic medications affect various body functions involving digestion, urination, salivation, and movement, they help treat many health conditions.

Anticholinergic medications are classified according to the receptors that they target:

• Antimuscarinic medications: This targets the muscarinic acetylcholine receptors found at the nerve endings at the smooth muscle cells, secretory glands, and eye. They are also found in the central nervous system. The majority of anticholinergic medications are antimuscarinics.
• Antinicotinic medications: These act on the nicotinic acetylcholine receptors located at the nerve endings of the neuromuscular junctions and are the target of muscle relaxing drugs.

Anticholinergic medications have been used for treating many diverse conditions such as:

• Asthma
• Chronic obstructive pulmonary disease (COPD)
• Diarrhea
• Irritable bowel syndrome (IBS)
• Muscle spasms
• Overactive bladder (OAB)
• Urinary incontinence
• Parkinson's disease
• Surgery and anesthesia
• Muscle relaxation
• Vomiting
• Gastrointestinal disorders
• Insomnia
• Dizziness
• Motion sickness
• Poisoning due to insecticides and poisonous mushrooms
• Psychiatric disorders

Anticholinergic medications have potential interactions with medications that have cholinergic actions.

The use of multiple drugs with anticholinergic properties may be problematic because of their cumulative anticholinergic side effects. The combined use of two or more anticholinergic medications should be avoided to minimize the risk of adverse drug effects.

Medications with anticholinergic properties that should not be combined include:

• Antidepressants
• Antihistamines
• Muscle relaxants
• Antispasmodics
• Anti-diarrheal medications
• Parkinson’s medications
• Antiarrhythmic medications
• Antipsychotics
• Overactive bladder (OAB) medications
• Acetylcholinesterase inhibitors
• Motion sickness medications
• Certain antiemetic medications
• Respiratory medications

Appropriate choice of anticholinergic medications and their dose help minimize undesirable side effects. With a suitable prescription, anticholinergic medications are usually safe.