8 Anticholinergic Medication Side Effects You Should Know About

Anticholinergics are a broad group of medications. A few examples include oxybutynin (Ditropan XL), ipratropium (Atrovent HFA), and scopolamine (Transderm Scop). And besides traditional anticholinergics, many other medications have anticholinergic properties. Examples include some tricyclic antidepressants, like nortriptyline (Pamelor), and common over-the-counter (OTC) medications, like diphenhydramine (Benadryl).

Anticholinergics work by blocking the activity of a chemical called acetylcholine. Acetylcholine regulates many body functions. This includes those involving your muscles, heart, and digestive system. So when you block acetylcholine, you can experience a wide range of effects. But, sometimes, these effects result in unwanted side effects.

Here, we’ll cover eight of the most important anticholinergic side effects you should know about.

1. Dry mouth

One of the most common anticholinergic side effects is dry mouth. Older adults are more at risk of experiencing dry mouth, but it can happen to anyone.

Dry mouth can happen because anticholinergics block acetylcholine in the mouth. Blocking acetylcholine in the mouth reduces the amount of saliva you make. Dry mouth may not seem like a big deal, but it can lead to serious health conditions if it becomes an ongoing problem. This includes trouble with chewing or swallowing, cavities, and infections in the mouth.

If you’re experiencing dry mouth, some home remedies might help. Chewing sugar-free gum, sucking on ice chips, or using saliva substitutes are options. But if your dry mouth feels severe and home remedies don’t help, talk to your healthcare provider. They may want to lower your dose or switch you to another medication altogether.

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2. Constipation

Anticholinergics slow down the movement of food through your digestive tract. This can cause constipation. Along with dry mouth, constipation is one of the reasons that anticholinergics are listed on the American Geriatrics Society (AGS) Beers Criteria. This is a list of medications that the AGS considers potentially harmful for adults who are 65 years of age and older.

If you experience constipation, lifestyle modifications may help. Staying hydrated, keeping an exercise routine, and eating foods high in fiber are a few things you can try. Taking an OTC laxative or fiber supplement can also help. Ask your healthcare provider or pharmacist for guidance when choosing an OTC product for constipation.

If your constipation continues or worsens, let your provider know. And if you notice signs that your constipation is severe (or that something else may be going on), reach out to your provider right away. A few warning signs include blood in your stool, pain with bowel movements, or constipation that lasts longer than a week.

3. Sweating less

Sweating less is another common anticholinergic side effect. For some people, this may not seem like a bad thing. In fact, some anticholinergic medications like Qbrexza (glycopyrronium) are first-choice medication options to reduce excessive sweating.

But there can be downsides to less sweat production with anticholinergics. Because your body isn’t sweating as much, you can overheat. In severe cases, this can cause heat exhaustion or heat stroke. Heat stroke is a medical emergency.

If you take anticholinergics, take steps to avoid overheating. Avoid being outside or exercising during the hottest part of the day. Drink water frequently and avoid dehydrating substances, like alcohol. If you notice signs of overheating — such as muscle cramps, a fever, or hot, red skin — seek emergency care.

4. Eye problems

Anticholinergic medications can affect the eyes in many ways. They can dry out your eyes, tighten eye muscles, and cause pupil dilation. They also relax certain eye muscles, which can cause blurry vision. In some cases, anticholinergic medications, like atropine (Isopto Atropine), are purposely used to dilate your pupils during an eye exam or surgery. But other times, eye-related side effects from anticholinergics are unwanted and bothersome.

Anticholinergics can also increase your risk of a serious eye condition called angle-closure glaucoma. When the pupils dilate, pressure inside the eye increases. This can lead to new or worsening cases of glaucoma. Let your healthcare provider know if you have any existing eye conditions before taking an anticholinergic.

5. Heart problems

Anticholinergics affect the body’s ability to regulate your heart rate. This may lead to an abnormal heart rate (arrhythmia) or a faster-than-usual heart rate (tachycardia). This can reduce blood flow to the heart. If your heart rate is too fast, you may have an increased awareness that your heart is beating. Or you may feel like your heart is pounding in your chest.

There’s some evidence suggesting that people who take multiple anticholinergics may be more likely to have serious heart problems over time. This is especially true in people who are older or who already have existing heart problems.

If you have an existing heart condition, talk to your healthcare provider before taking an anticholinergic. And if you’re taking an anticholinergic and notice signs of a faster heart rate, let your provider know.

6. Difficulty peeing

Anticholinergic medications prevent the muscles in your bladder from tightening. This can cause urinary retention (trouble peeing). In some cases, anticholinergics are used specifically to treat conditions where you have to pee more often than normal, like overactive bladder. For example, oxybutynin and solifenacin (Vesicare) are anticholinergics that treat this condition.

But long-term urinary retention can cause more serious problems, such as infections and kidney damage. For this reason, anticholinergics should be used with caution in those who are already at risk of urinary retention. This includes people with certain urinary conditions, including benign prostatic hyperplasia.

7. Dementia

Some research has found that anticholinergics may be linked to a greater risk of dementia. And the risk may be greater if you use these medications for a long period of time (many years). The term dementia describes a group of conditions that affect the brain. They may cause symptoms like forgetfulness and an inability to care for yourself.

It’s not certain how anticholinergics raise the risk of dementia. It may be that they increase inflammation in the body, which is linked to dementia. It may also be that anticholinergics lower levels of acetylcholine. Low levels of this chemical are seen in people with Alzheimer's disease (a well-known type of dementia). In fact, medications that prevent the breakdown of acetylcholine can help treat Alzheimer’s disease. This includes donepezil (Aricept) and rivastigmine (Exelon).

Anticholinergics should be used with caution in people with pre-existing dementia. If you do need anticholinergics, it’s best to take them at the lowest dose for the shortest amount of time.

8. Anticholinergic toxicity

If many anticholinergic side effects occur together and become severe, it’s called anticholinergic toxicity. It’s rarely life-threatening, but it may require care in a hospital.

Anticholinergic toxicity is most likely to happen if you take too many anticholinergic medications at once or if you take higher than normal doses. It’s more likely in older people and people who take multiple anticholinergics. This is why it’s important to give your pharmacist a list of all the medications you take so they can check for you.

Anticholinergic toxicity has a few classic symptoms. Here’s a memory device to help you remember them:

• Red as a beet (flushing of the skin)

• Dry as a bone (dry mouth, eyes, and skin)

• Blind as a bat (dilated pupils)

• Mad as a hatter (confusion, delirium, agitation)

• Hot as a hare (overheating and fever)

• Full as a flask (trouble peeing)

If you have anticholinergic toxicity, the goal is to manage your symptoms so they don’t get worse. If you suspect that you or a loved one is experiencing anticholinergic toxicity, seek emergency help immediately by calling 911. You can also contact Poison Control 24 hours a day at 1-800-222-1222.

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Written by:

Sarah Lobello Pearson, PharmD

Sarah Pearson is a practicing pharmacist with over 10 years of experience in the field. She received her doctorate in pharmacy from the University of Georgia in Athens, GA.

Edited by:

Amy B. Gragnolati, PharmD, BCPS

Amy Gragnolati, PharmD, BCPS, is a pharmacy editor for GoodRx. Amy currently holds her pharmacist license in Georgia and California.

Reviewed by:

Christina Aungst, PharmD

Christina Aungst, PharmD, is a pharmacy editor for GoodRx. She began writing for GoodRx Health in 2019, transitioning from freelance writer to editor in 2021.

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