What are anticholinergic side effects?

From the Guidelines

Anticholinergic side effects are a group of symptoms that occur when medications block acetylcholine, a neurotransmitter in the body, and can be particularly problematic in older adults due to their increased sensitivity and risk of cognitive impairment, as noted in a 2021 study published in the Mayo Clinic Proceedings 1.

Common Anticholinergic Side Effects

These effects commonly include:

• Dry mouth
• Blurred vision
• Constipation
• Urinary retention
• Increased heart rate
• Confusion
• Decreased sweating which can lead to overheating Many medications can cause these effects, including:
• Antihistamines (like diphenhydramine)
• Tricyclic antidepressants (such as amitriptyline)
• Certain antipsychotics (like olanzapine)
• Some Parkinson's medications
• Bladder medications (such as oxybutynin)

Management and Prevention

Management typically involves:

• Reducing the dose
• Switching to alternative medications with fewer anticholinergic properties
• Treating specific symptoms Patients taking medications with anticholinergic effects should:
• Stay well-hydrated
• Avoid hot environments to prevent overheating As highlighted in a study from the Journal of Allergy and Clinical Immunology in 2008, first-generation antihistamines have significant potential to cause sedation, performance impairment, and anticholinergic effects, which can be particularly dangerous in older adults 1.

Special Considerations

Older adults are more sensitive to the psychomotor impairment promoted by first-generation antihistamines and are at increased risk for complications such as fractures and subdural hematomas caused by falls, as well as adverse anticholinergic effects, making it crucial to approach their use with caution in this population 1.

Recent Guidelines

A 2021 study published in the Mayo Clinic Proceedings emphasizes the importance of deprescribing strongly anticholinergic medications in older patients to minimize their adverse effects on cognition, functionality, and overall quality of life 1.

From the Research

Anticholinergic Side Effects

Anticholinergic side effects are adverse effects caused by drugs that block the action of the neurotransmitter acetylcholine in the brain and peripheral tissues. These side effects can range from mild to severe and can be potentially lethal.

• Common anticholinergic side effects include:
  • Dry mouth
  • Constipation
  • Urinary retention
  • Blurred vision
  • Drowsiness
  • Confusion
  • Cognitive impairment
  • Increased risk of falls
  • Increased risk of dementia and death in older people 2, 3, 4, 5, 6

Vulnerable Populations

Certain populations are more vulnerable to anticholinergic side effects, including:

• Older people, who may already have cognitive impairment or other health conditions that can be exacerbated by anticholinergic drugs 2, 3, 4
• People with mental illness, who may be more susceptible to the adverse neuropsychiatric effects of anticholinergics 3
• People taking multiple medications with anticholinergic effects, who may be at risk of cumulative anticholinergic burden 2, 3, 4

Management and Prevention

To minimize the risk of anticholinergic side effects, clinicians can:

• Use tools to assess anticholinergic burden and make informed decisions about medication use 2, 3
• Avoid or reduce the use of anticholinergic drugs when possible 4, 5
• Monitor patients for signs of anticholinergic side effects and adjust medication regimens accordingly 3, 5