6 Oxybutynin Interactions: Benadryl, Metoclopramide, and More

Oxybutynin is an oral medication that treats symptoms of overactive bladder (OAB). It also comes as a transdermal patch (Oxytrol, Oxytrol for Women) that you apply to the skin. Oxybutynin can be helpful for many people, but it may not be right for everyone. 

Before starting treatment with oxybutynin, it’s good to be aware of its potential drug interactions. Your healthcare team can be a helpful resource for managing these up front. So be sure to share your current medication list with them to review.

Here, we’ll cover six notable oxybutynin interactions and strategies for managing them.

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1. Anticholinergic medications such as Benadryl

Oxybutynin is an anticholinergic medication. It blocks the effects of a chemical called acetylcholine. Acetylcholine has several roles in the body, including bladder emptying. If you have OAB, anticholinergics like oxybutynin reduce the urge to pee.

But anticholinergics have other effects, too. And as a result, they commonly cause side effects like dry mouth and constipation. Confusion, which can increase the risk of falls, is also possible. Combining oxybutynin with other anticholinergic medications can make these side effects worse. Other anticholinergic medications include:

• Diphenhydramine (Benadryl) 

• Scopolamine (Transderm Scop)

• Hyoscyamine (Levsin)

• Benztropine

• Glycopyrrolate (Robinul)

It’s usually best to avoid taking multiple anticholinergic medications at once, if possible. This is especially true for older adults. There may be situations in which your prescriber recommends taking more than one. In that case, it’s a good idea to alert them to any new or bothersome side effects you experience.

2. Antifungals such as ketoconazole

Azole antifungals, such as ketoconazole, block liver enzymes (proteins) that break down oxybutynin. This can cause higher levels of oxybutynin in the body, leading to an increased risk of side effects.

If you need to take an antifungal, your prescriber may temporarily lower your oxybutynin dosage. But be sure to tell them if you notice new or worsening side effects. 

EXPERT PICKS: WHAT TO READ NEXT

• Oxybutynin side effects: Do you experience dry mouth after taking oxybutynin? Here’s a list of potential oxybutynin side effects and how to manage them.

• Oxybutynin dosages: Oxybutynin comes in several forms, from oral pills to topical patches. Learn more about oxybutynin dosages and what to do if you miss your dose.

• How they compare: Oxybutynin is one of several medications available for overactive bladder. Here’s how medications like oxybutynin, Detrol, and Myrbetriq compare.

3. Metoclopramide

Metoclopramide (Reglan) treats symptoms of gastroparesis (slowed stomach emptying) caused by diabetes. It’s also sometimes used to treat health conditions like gastroesophageal reflux disease (GERD). The medication helps food move faster through your digestive tract. But oxybutynin can have the opposite effect, slowing down digestion. 

When taken together, oxybutynin can make metoclopramide less effective. Because of this, your prescriber may recommend an alternative medication. 

4. Medications that cause drowsiness

Oxybutynin can cause drowsiness. And taking it with other medications that cause drowsiness can worsen the effects. It can also make activities that require you to be alert, such as driving a car, more dangerous.

Other medications that can cause drowsiness include:

• Opioids, such as oxycodone (Roxicodone, OxyContin)

• Muscle relaxers like cyclobenzaprine and tizanidine (Zanaflex)

• Benzodiazepines, which include alprazolam (Xanax) and lorazepam (Ativan)

• Some antidepressants, such as trazodone (Desyrel) and mirtazapine (Remeron)

• Anti-seizure medications like topiramate (Topamax) and lamotrigine (Lamictal)

Your prescriber will help you manage this interaction, if needed. But be sure to let them know if you notice that you’re feeling extra tired or sleepy after a medication change.

Keep in mind: Several factors beyond medication can cause drowsiness. If you’re feeling sleepy, look at your sleep schedule, stress levels, and exercise routine. How much caffeine you drink and any other health conditions you have could also play a role.

5. Medications that cause dry mouth

As mentioned, dry mouth is a common oxybutynin side effect. Taking it with other medications that cause dry mouth can make this side effect worse. These medications include:

• Other medications that treat OAB, such as tolterodine (Detrol) and solifenacin (Vesicare)

• Other anticholinergic medications

• Benzodiazepines

• Opioids

• Stimulants, such as Adderall (amphetamine salts) and Ritalin (methylphenidate)

• Antipsychotic medications, such as quetiapine (Seroquel) and risperidone (Risperdal)

Dry mouth isn’t usually serious, but it can be uncomfortable. It can also increase your risk for dental problems long term. Some things you can try at home to relieve dry mouth include:

• Chewing sugar-free gum

• Sucking on ice chips

• Sipping cool liquids throughout the day

• Using saliva substitutes such as BioXtra or Biotene

If you have dry mouth that becomes bothersome, let your prescriber know. They may be able to lower your dosage of oxybutynin or recommend an alternative medication.

6. Medications that can cause constipation

Oxybutynin can also cause constipation, as discussed above. This side effect can be worse if you take oxybutynin with other medications that cause constipation. Examples include:

• Other OAB medications

• Opioids

• Iron supplements

• Tricyclic antidepressants like amitriptyline and nortriptyline (Pamelor)

• Nonsteroidal anti-inflammatory drugs (NSAIDs) like ibuprofen (Advil, Motrin) and naproxen (Aleve, Naprosyn)

• Antihistamines like diphenhydramine, famotidine (Pepcid), and cimetidine (Tagamet HB)

Staying hydrated, eating plenty of fiber, and exercising can help prevent and treat constipation. But if you have constipation that’s persistent or gets worse, talk to your prescriber. They may suggest constipation remedies, such as laxatives, or adjustments to your medications.

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Written by:

Austin Ulrich, PharmD, BCACP

Austin Ulrich, PharmD, BCACP, is a board-certified ambulatory care clinical pharmacist. In his early career, he provided direct patient care in a variety of settings, including hospital and community pharmacies, and in a primary care clinic as a clinical pharmacist.

Edited by:

Alyssa Billingsley, PharmD

Alyssa Billingsley, PharmD, is the director of pharmacy content for GoodRx. She has over a decade of experience as a pharmacist and has worked in clinical, academic, and administrative roles.

Reviewed by:

Alex Evans, PharmD, MBA

Alex Evans, PharmD, MBA, has been a pharmacist for 12 years. His first job was floating in a community chain pharmacy.

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