Anticholinergic burden calculator
Add each of a patient's medications. The tool sums the Anticholinergic Cognitive Burden (ACB) score across the regimen. Total 3 or higher is considered clinically meaningful. The higher the total, the more cognitive slowing, fall risk, and long-term dementia risk to consider.
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Total burden
Add medications to see the total ACB score.
Reference data current as of July 2026. Source: Boustani M et al. Impact of anticholinergics on the aging brain. Aging Health. 2008; Anticholinergic Cognitive Burden Scale (Indiana University CAR).
About this tool
Anticholinergic burden accumulates across medications and drives real clinical harm, particularly in older adults. This calculator uses the Anticholinergic Cognitive Burden (ACB) Scale (Boustani M et al., Aging Health 2008), which is one of the widely used scoring systems for this problem. It scores drugs 0 to 3 based on muscarinic receptor blockade and CNS penetration.
Cumulative scores of 3 or higher are considered clinically meaningful. Higher totals (5, 7, 10) predict more severe cognitive slowing, higher fall risk, and long-term dementia risk. The Coupland CAC et al. BMJ 2019 case-control study of 58,000+ dementia cases showed 50 percent elevated dementia risk in patients with prolonged high anticholinergic exposure.
The calculator covers common psychiatric medications, common non-psychiatric drugs that show up in polypharmacy (antihistamines, bladder drugs, GI antispasmodics, antiemetics, muscle relaxants, some cardiac drugs), and the specific psychiatric drugs where anticholinergic burden matters most (TCAs, clozapine, olanzapine, benztropine, paroxetine, quetiapine).
For patients with high cumulative burden, the intervention is often substitution rather than symptomatic management. See the anticholinergic burden side effect page for common substitution options.
Common questions
- What is the ACB Scale?
The Anticholinergic Cognitive Burden (ACB) Scale scores each drug from 0 (no effect) to 3 (severe effect) based on its muscarinic receptor blockade and CNS penetration. Total scores are calculated by adding the scores of all a patient's drugs. A total ACB score of 3 or higher is considered clinically meaningful and associated with cognitive impairment, falls, delirium risk, and long-term dementia risk in older adults.
- Which drugs have the highest anticholinergic burden?
Tricyclic antidepressants (amitriptyline, nortriptyline, doxepin, clomipramine, imipramine), clozapine, olanzapine, first-generation antihistamines (diphenhydramine, doxylamine, hydroxyzine), bladder antimuscarinics (oxybutynin, tolterodine), benztropine, trihexyphenidyl, and some antipsychotics all score 3 on the ACB Scale.
- Why does anticholinergic burden matter?
High cumulative anticholinergic burden causes cognitive slowing, dry mouth, urinary retention, constipation, falls, delirium, and is associated with elevated long-term dementia risk. See our anticholinergic burden side effect page for full detail on Coupland et al. BMJ 2019 dementia data.
- What can I substitute for high-ACB drugs?
Common substitutions: diphenhydramine for sleep → melatonin, ramelteon, or low-dose doxepin (Silenor 3-6 mg); paroxetine → sertraline or escitalopram; oxybutynin → mirabegron; olanzapine → aripiprazole or lumateperone; amitriptyline for depression → SSRI or SNRI or bupropion. See individual drug pages.
- Is this tool a personalized recommendation?
No. It calculates a published score from a published scale. It does not know patient age, cognitive function, kidney or liver function, indications, or trade-offs. Every prescribing decision belongs with the licensed clinician who has the full picture. This is a reference calculation aid.