Anticholinergic burden (ACB)

Adverse effects of anticholinergic medications may contribute to events such as fall, delirium, and cognitive impairment in older patients. A recent study suggests an association between the use of anticholinergic drugs and the subsequent development of dementia.

Other adverse effects include blurred vision, confusion, constipation, dry mouth, increased temperature and heart rate, increased intraocular pressure, pupil dilation, urinary retention.

First generation antihistamines are also sedative.

Medicines are assigned an ACB score by TaperMD of no ACB (= 0) to definite (= 3). The ACB is cumulative.

If an older adult is taking one medication with an ACB score greater than 2 or having a total ACB score of 3 or more for all medications, consider reducing or changing medications. Where this is not possible, reduce doses as much as possible.


  1. Boustani MA, Campbell NL, Munger S, Maidment I, Fox GC. Impact of anticholinergics on the aging brain: a review and practical application. Aging Health. 2008;4(3):311-20.
  2. Richardson Kathryn, Fox Chris, Maidment Ian, Steel Nicholas, Loke Yoon K, Arthur Antony et al. Anticholinergic drugs and risk of dementia: case-control study BMJ 2018.
  3. Common anticholinergic drugs like Benadryl linked to increased dementia risk. Harvard Health Publishing.
  4. Patient Handout First-generation antihistamines. Bruyere Research Institute at
  5. Jama: Anticholinergic Drug Exposure and the Risk of Dementia A Nested Case-Control Study.