Color & Control:

What you need to know about anticholinergic medications

Some medications you take for allergies, sleep, nausea, depression or incontinence belong to a group of medications called anticholinergic medications. They work by blocking a chemical in your body called acetylcholine. 

By Janet Currie and Johanna Trimble

Acetylcholine is used in many parts of your body and helps you stay alert, keep a steady heart rate, breathe, digest food, sweat and empty your bladder. When you take an anticholinergic medication, it acts on many parts of your body at the same time.

How do I know if I’m taking an anticholinergic medication?
Anticholinergic medications can be prescribed by your healthcare professional or bought over the counter (also called OTC) at a store without a prescription. Here are some of the most common types of anticholinergic medications.

• Allergy medications (for example, Benadryl® – diphenhydramine)

• Anti-nausea medications (for example, Gravol® – dimenhydrinate)

• Antidepressants (for example, Paxil® – paroxetine)

• Antipsychotics (for example, Seroquel® – quetiapine)

• Bladder control medications (for example, Ditropan® – oxybutynin)

• Sleeping pills (for example, trazodone or OTC medications like Nytol® or Sominex®)

• Muscle relaxants (for example, Robaxin® – methocarbamol)

• All opioids 

• Combination medications (for example, Tylenol PM® or other medications with “PM” in their name which include the ingredient diphenhydramine)*

Did you know?
Strong anticholinergic ingredients can be found in many of the over-the-counter medications you buy. Always read the ingredient list on the package of any medications you buy over-the-counter. If there are two or more ingredients it is called a combination medication. A combination medication may have an anticholinergic medication in the ingredients list. For example, diphenhydramine or dimenhydrinate are strong anticholinergic medications found in many over-the-counter products.

Older adults are most at risk
As we get older, our liver and kidneys aren’t able to process medications as well so we become more sensitive to them. Also, many older adults have more than one health condition and may take many medications including one or more anticholinergics. The more medications a person takes, the more likely it is that he or she will have unwanted side effects.

What are the side effects?
When you take an anticholinergic medication, it can act on many different parts of your body at the same time. This can cause unwanted side effects. Your risk of side effects is higher if you are taking higher doses, you’re taking more than one or you’ve taken this medication for a long time. 

Side effects can appear at any time, even many years after starting a medication. As time passes, you may think new symptoms are a new illness, when in fact they are side effects from your medications. A few common side effects of anticholinergic medications can be seen in the diagram on the left.

Do they increase my risk of dementia?
A few studies have suggested that older adults who use anticholinergic medications for a long time or at higher doses may have a higher risk of dementia. Research has not proven this, but it does suggest that older adults should limit the number of anticholinergic medications they take and use the lowest dose for the shortest length of time. 

Janet Currie is a social worker who has been involved with patient and medication safety issues for over 17 years.
Johanna Trimble is a patient safety advocate and member of the BC Patient Voices Network.

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