Some Medications That May Cause Cognitive Impairment

Q: Can any medicines - particularly antibiotics - cause dementia? Is dementia ever curable?

A: Dementia is a loss of cognitive (mental) ability which may affect the ability to solve problems, language, memory, and attention. This loss of cognitive function must be present for at least six months for dementia to be diagnosed. Delirium is a short-term loss of mental function and may be defined as a short term confused state. Delirium is often caused by infections and medications such as those used to treat anxiety (e.g., alprazolam), medications used for high blood pressure (e.g., hydrochlorothiazide), some antidepressants (eg. amitriptyline) and some antibiotics (eg. ciprofloxacin). Delirium is often reversible if the cause for delirium is removed. Dementia is less often caused by medications but is often caused by diseases such as Alzheimer

The two main forms of memory are declarative memory and procedural memory. Declarative memory is memory of past events and facts, whereas procedural memory is memory of how to carry out routine-based tasks, such as the memory of how to ride a bike. The type of memory most easily affected by recreational and prescription drugs is short-term declarative memory. The side-effects of prescription drugs tend to be reversible, but continued use of drugs that impair cognitive ability may, in some cases, lead to permanent damage.

Anti-Anxiety Medications

Anti-anxiety medications in the benzodiazepine class may cause short-term memory loss. The benzodiazepines most commonly prescribed for anxiety are alprazolam and diazepam. Alprazolam, which is sold under the brand name Xanax, was initially developed as a sleep medication but is now primarily prescribed for its axiolytic effects. Diazepam, which is sold under the brand name Valium, is a muscle relaxant primarily prescribed as an anticonvulsant and anti-anxiety drug. Because the benzodiazepines enhance the effects of the brain inhibitory neurotransmitter GABA, drugs in this class slow down neurological functions, including memory functions, reports a research team in the March 2002 issue of “Consciousness and Cognition.”

Some Medications That May Cause Cognitive Impairment

Antiarrhythmic Agents
Disopyramide, Quinidine, Tocainide

Phenylpropanalamine, Diphenhydramine, Clorpheniramine, Brompheniramine, Pseudoephedrine

Cephalexin, Cephalothin, Metronidazole, Ciprofloxacin, Ofloxacin

Cardiotonic Agents

Anticholinergic Agents
Benztropine, Homatropine, Scopolamine, Trihexyphenidyl


Amitryptyline, Imipramine, Desipramine, Doxepin

H2 receptor Antagonists
Cimetidine, ranitidine

Phenytoin, Valproic acid, Carbamazepine

Immunosuppresive Agents
Cyclosporine, Interferon

Promethazine, Hydroxyzine, Metroclopramide,

Narcotic Analgesics
Codeine, Hydrocodone, Oxycodone, Meperidine, Prochlorperazine Propoxyphene

Antihypertensive Agents
Propranolol, Metoprolol, Atenolol, Verapamil, Methyldopa, Prazosin, Nifedipine

Muscle Relaxants
Baclofen, Cyclobenzaprine, Methocarbimol

Antineoplastic Agents
Chlorambucil, Cytarabine, Interleukin-2

Nonsteroidal Anti-inflammatory Agents
Aspirin, Ibuprofen, Indomethacin, Naproxen, Sulindac

Antimanic Agents

Radiocontrast Agents
Metrizamide, Iothalamate, Iohexol

Anti-Parkinsonian Agents
Levodopa, Pergolide, Bromocryptine

Alprazolam, Diazepam, Lorazepam, Flurazepam, Clonazepam, Phenobarbital, Chloral hydrate

Haloperidol, Chlorpromazine, Thioridazine

Complications to Be Aware of When Talking With Families

  •   The family plays a key role by providing detailed history concerning mental status changes.
  •   Family members may minimize or exaggerate subtle yet progressive symptoms (such as the inability to balance the checkbook, loss of inhibition, verbal or physical abuse of/by spouse, psychosocial stressers, or other factors).
  •   Different family members bring their own perception of the severity and impact of cognitive changes. 

Medications List Review

  • Many commonly used medications can be responsible for cognitive changes; therefore, careful review of medication usage is essential, including prescription and nonprescription drugs.
  •   Patients and family should be reminded to bring all of their over-the-counter medications, herbal remedies, nutritional supplements, and prescription medications to the office.


AHCPR Clinical Practice Guidelines. No. 19. Publication #97-0702, Washington, DC, US Department of Health and Human Services, November, 1996

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