Glycopyrronium Drug Interactions: What to Avoid and What to Tell Your Doctor

Glycopyrronium (glycopyrrolate) has a significant interaction profile. Because it blocks muscarinic receptors throughout the body, combining it with other medications that have similar anticholinergic activity — or that affect GI motility, heart rate, or drug absorption — can cause additive effects or harmful outcomes. Here's what you and your prescriber need to know.

Critical Interactions: Avoid or Use Extreme Caution

Other anticholinergic medications (major): Combining glycopyrronium with any other anticholinergic drug dramatically increases the risk and severity of anticholinergic side effects: extreme dry mouth, urinary retention, severe constipation, tachycardia, confusion, and potentially dangerous heat stroke. Examples include oxybutynin, tolterodine, solifenacin, benztropine, trihexyphenidyl, and diphenhydramine (found in Benadryl and many OTC sleep aids). Tell your doctor about every anticholinergic you take.

Umeclidinium-containing inhalers (contraindicated): Combining glycopyrronium inhalers with umeclidinium (Incruse Ellipta, Anoro Ellipta, Trelegy Ellipta) constitutes duplicate LAMA therapy and is contraindicated. The additive anticholinergic burden to the airway and systemically creates risk without added benefit.

Solid oral potassium chloride (major, contraindicated with Cuvposa): Glycopyrronium slows GI transit. When solid (wax matrix) potassium chloride tablets are taken with glycopyrronium, they can sit in the GI tract too long, causing local irritation and GI lesions. Solid-dose KCl is contraindicated with Cuvposa; liquid or powder KCl forms may be acceptable.

Glucagon (including intranasal glucagon): Both drugs inhibit GI motility via different mechanisms. Combination increases the risk of severe nausea, vomiting, and GI complications. Avoid combining.

Moderate Interactions: Use With Monitoring

Amantadine: Amantadine (used for Parkinson's disease and influenza) has inherent anticholinergic activity. Combining with glycopyrronium increases anticholinergic side effects. Your doctor may need to reduce the glycopyrronium dose if you take amantadine.

Metformin: Glycopyrronium increases metformin plasma levels by reducing renal excretion via inhibition of tubular secretion. This can increase metformin's effectiveness — but also its GI side effects and rarely risk of lactic acidosis at high doses. Monitor clinical response if you take metformin.

Atenolol (and certain other beta-blockers): Glycopyrronium increases atenolol bioavailability by slowing gastric emptying, leading to more complete absorption. This may lower blood pressure or heart rate more than expected. Your doctor may need to adjust your atenolol dose.

Digoxin (slow-dissolution tablets): By slowing GI transit, glycopyrronium increases the absorption and blood levels of digoxin from slow-release oral formulations. This can increase digoxin toxicity risk. If you take digoxin tablets, your doctor should monitor levels closely.

Haloperidol and other antipsychotics: Many antipsychotics have inherent anticholinergic activity. Combining with glycopyrronium can worsen anticholinergic burden, potentially causing urinary retention, constipation, and cognitive effects.

Pramlintide (used with insulin for diabetes): Both drugs slow gastric emptying. Combination can impair glucose management and worsen GI side effects.

The Anticholinergic Burden Problem

Anticholinergic effects are additive. Many common medications have some anticholinergic activity beyond the drugs listed above:

Antihistamines: diphenhydramine (Benadryl), hydroxyzine, cetirizine (mild)

Tricyclic antidepressants: amitriptyline, imipramine, nortriptyline

Bladder medications: oxybutynin, tolterodine, solifenacin, darifenacin

Antispasmodics: dicyclomine, hyoscyamine

Muscle relaxants: cyclobenzaprine

Some antipsychotics and certain antidepressants

When multiple low-level anticholinergic medications are taken together (called high anticholinergic burden), the cumulative effect can cause significant side effects, especially in older adults. Clinicians use the Anticholinergic Cognitive Burden (ACB) Scale to quantify this risk.

Food and Drink Interactions

For oral glycopyrrolate (especially Cuvposa), food significantly reduces absorption. Take oral glycopyrrolate at least 1 hour before or 2 hours after meals for best effect. High-fat meals are particularly likely to reduce peak drug levels.

Alcohol can worsen dry mouth and may increase the risk of confusion in patients taking glycopyrrolate. Minimize alcohol consumption while on this medication.

What to Tell Your Doctor and Pharmacist

Always tell your prescriber and pharmacist about:

All prescription medications, especially antipsychotics, antidepressants, bladder drugs, or GI medications

All OTC medications, including antihistamines (Benadryl, Zyrtec, Unisom), sleep aids, and cold medications

Supplements and herbal products — especially anticholinergic herbs such as henbane, belladonna, or jimsonweed (Datura)

If you take metformin, digoxin, atenolol, or potassium supplements

Any glaucoma diagnosis or risk factors

For more on side effects that can be worsened by interactions, see our post on glycopyrronium side effects.

If you're also having trouble finding your glycopyrronium prescription, medfinder can check pharmacy availability near you.