Gary S. Moak, M.D.

You’ve probably never heard of anticholinergic medications, but you need to know about them. Here’s why: Anticholinergic medications can cause forgetfulness, or more severe memory or more widespread cognitive impairment resembling Alzheimer’s disease. But it’s worse. Some medical research suggests that use of these medications increases the risk of developing Alzheimer’s disease.

So what are anticholinergic medications? This may sound flippant, but anticholinergic medications are drugs having anticholinergic effects. Acetylcholine is a neurotransmitter with important functions in the brain and throughout the body. Anticholinergic medications block the action of acetylcholine.

Anticholinergic effects are helpful in relieving certain health problems. More on this in a minute. But they also cause a number of side effects including dry mouth, constipation, difficulty starting the urine stream, and blurry vision. When severe, anticholinergic side effects can cause urinary retention or bowel obstruction.

These side effects usually are just annoying for younger people, but they can be very serious for older adults. Even more worrisome is the cognitive impairment that can occur. Over the years I have treated many patients who were told, erroneously, that they had Alzheimer’s disease. I cured them of their “Alzheimer’s” by taking them off several anticholinergic medications. Because of experience like this, geriatric psychiatrists advise avoiding anticholinergic medications, whenever possible.

If anticholinergic medications can cause such severe cognitive problems, why are they given to older adults? Anticholinergic effects can relieve some common problems that make life miserable for some older adults. Medications for overactive bladder disorder work because they have anticholinergic effects. These effects relax the bladder, reducing frequent urination and urge to void. Oxybutynin (Ditropan) and tolterodine (Detrol) are two examples of highly anticholinergic medications for overactive bladder disorder. Anticholinergic medications also can reduce diarrhea and cramps in older people with irritable bowel syndrome. They work by slowing down passage in the colon. Dicyclomine (Bentyl) and hyoscyamine (Levsin) are examples of medications used for this purpose.

When taken these bladder and bowel medications do not only go to the bladder and bowel. It would be nice if they did. Unfortunately, like all ingested medications, once they are digested, the blood stream carries them throughout the body. Their effects in parts of the body where they are not needed is one way anticholinergic medications, and many other types of medications, cause side effects.

Medications of all types also can cause side effects through actions that are unrelated to their intended effect. Pharmaceutical researchers would like to discover medications with a single action, but it is not so easy. Many of the medications we have, for a wide range of conditions, do not have a single action; they cause other effects. For example, tamsulosin (Flomax), a medication for the symptoms of enlarged prostate, can lower blood pressure or cause nasal congestion. Medications to open the airways in sufferers of asthma or emphysema can cause anxiety, jitters, or tremors. Beta-blockers can cause fatigue.

In just this way, a number of medications not used for their anticholinergic effects have anticholinergic side effects. Examples include diphenhydramine (Benadryl, used for itching, allergies, sleep), meclizine (Antivert, used for vertigo), cyclobenzaprine (Flexeril, used for muscle spasms), ranitidine (Zantac, used to reduce stomach acid), paroxetine (Paxil, used for depression), olanzapine (Zyprexa, used for psychosis) and amitriptyline (Elavil, an older antidepressant now mostly used for headaches and chronic pain). These drugs all have different purposes and actions, and all are highly anticholinergic.

Doctors should be very cautious about prescribing anticholinergic medications to older adults, but often are not. Geriatric specialists work hard to limits their patients’ exposure to anticholinergic medications. But many of those who are not geriatric specialists may not know which medications have anticholinergic side effects or that these can be a problem for elderly patients.

Older adults with Alzheimer’s disease are especially vulnerable. Anticholinergic medications can make their symptoms worse. Or they may counteract anti-Alzheimer medications such as donepezil (Aricept). Donepezil, and other such cholinesterase inhibitors, help patients with Alzheimer’s disease by increasing acetylcholine levels in the brain. Recall that anticholinergic medications block acetylcholine.

It is not always possible to avoid all anticholinergic medications. Some older adults need a particular medication that has anticholinergic side effects. This may be okay. A single anticholinergic medication may not, by itself, always cause a problem. Often it is the additive effect of two or more anticholinergic medications being taken together that causes the biggest problems. This is why it is so important for doctors to monitor all of their patients’ medications and consider this list when prescribing any new treatment.

Updated May 2016

Moak Center for Healthy Aging