Anticholinergic Medications

Medically reviewed by Smita Patel, DO

Anticholinergic drugs are drugs that block the action of acetylcholine—a chemical messenger in your brain that plays a role in memory, learning, and muscle movement. These drugs affect your brain and muscles in a variety of ways. That said, they can help treat several health conditions ranging from Parkinson's disease or depression to allergies or nausea.

You can take these drugs via an oral pill. While these drugs require a prescription, some are available over the counter.

What Do Anticholinergics Do?

Anticholinergics block acetylcholine signaling. Acetylcholine is particularly important for your parasympathetic nervous system. The parasympathetic nervous system is part of the nervous system that regulates your body when you are resting and relaxed. Blocking acetylcholine affects several muscles in your body that aren’t normally under your conscious control, like ones in the gastrointestinal tract, lungs, urinary tract, or eyes.

In general, anticholinergics help your muscles be more alert and less relaxed. For example, these drugs may help your pupils dilate (to take in more light) or slow down muscle contraction in the gastrointestinal tract (to slow down digestion). These medications work quickly—generally between a few minutes and a couple of hours.

Types of Anticholinergic Drugs

There are several anticholinergic drugs available and the one that you receive will depend on the underlying condition(s) you have. You can take most anticholinergics via an oral pill, but certain subtypes have different medication routes. Consider the following:

Many other medications may have mild to moderate anticholinergic effects. These effects can add up if you are taking multiple drugs. Ask your pharmacist or healthcare provider if you are unsure whether any of your prescription or over-the-counter (OTC) drugs are anticholinergics.

Potential Side Effects

Because they affect the nervous system and muscles all over the body, anticholinergics can have several potential side effects. Side effects are more likely to occur if you take a high dose of anticholinergic drugs.

Mild potential side effects may include:

• Dry mouth or dry eyes

• Constipation

• Blurry vision

• Increased heart rate

• Drowsiness

• Anxiety or restlessness

• Trouble concentrating

These side effects usually go away promptly after you stop taking the drug. However, you should never start or stop using a medication without the consent of your healthcare provider.

Drugs with high anticholinergic properties can sometimes have more severe side effects, like:

• Increased heart rate

• Ileus (temporary lack of muscle contractions in the gastrointestinal tract)

• Respiratory illnesses

• Urinary tract infections

• Seizures

• Hallucinations

• Trouble walking

While these side effects usually improve after you stop taking the drug, it can take some time to recover from complications (e.g., an infection) in some cases. You are also more likely to have severe side effects if you have underlying health conditions.

Other Considerations

The risks of serious side effects are generally greater in people 65 or older. Older adults using anticholinergics may also have a higher risk of poorer physical and mental functioning, an increased risk of falls, heart problems such as a heart attack, and increased rates of death. These risks are particularly high for older adults who live with underlying health conditions like heart disease, balance problems, or cognitive impairment.

For these reasons, experts recommend minimizing the use of anticholinergics in older adults. In some cases, the benefits of a specific drug are worth it. But other times, a different treatment approach is helpful.

Scientists have developed alternatives with less anticholinergic activation, which may be safer for older adults. Ask your healthcare provider about these options:

• Prozac (fluoxetine) for depression

• Seroquel (quetiapine) for schizophrenia

• Zyrtec (cetirizine) for allergies

• Sinemet (levodopa) for Parkinson's disease

• Tylenol (acetaminophen) for muscle spasms or pain

• Myrbetriq (mirabegron) for an overactive bladder

When to Contact Your Healthcare Provider

You may want to discuss your full medication list with your healthcare provider, including potential over-the-counter anticholinergic drugs, like Benadryl (diphenhydramine) or Tagamet (cimetidine). If your age or other health conditions put you at risk of serious side effects, it's important to discuss these concerns with your provider before using anticholinergics.

If you just started taking an anticholinergic and experience side effects, like difficulty urinating or changes to your emotional well-being, ask your provider if stopping the medication or changing the dosage is right for you.

A Quick Review

Anticholinergics are medications that block acetylcholine—a chemical messenger that affects the brain, muscles, and overall nervous system. Several medications qualify as anticholinergics.

Many people use these drugs for a variety of conditions, such as depression, nausea, allergies, muscle spasms, and Parkinson's disease. However, these medications may pose significant side effects in older adults, so it's important to talk with your healthcare provider before starting treatment.

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