Bentyl (dicyclomine) With Zyrtec Interaction

The pharmacist discusses the use of Bentyl (dicyclomine) with Zyrtec (cetirizine).

Aug 02, 2018

Liv asked

Is it safe to take Bentyl and Zyrtec together ?


Bentyl (Dicyclomine) and Zyrtec (Cetirizine) can both cause anticholinergic side effects. Anticholinergic side effects may include dry mouth, dry eyes, blurred vision, urinary retention and constipation.  Taking both medications together can cause an increase in incidence of these side effects.  Patients can take these medications together but should be aware of these possible side effects and should not take these medications together if the side effects become severe.

Also, both medications have the potential to cause drowsiness. Taking both together may have an additive effect and cause more drowsiness.  Patients should take the necessary precautions with driving and while operating machinery.  Below is some additional information on both medications.

Bentyl (Dicyclomine)

Bentyl (Dicyclomine) is used in the treatment of gastrointestinal motility disorders or irritable bowl syndrome.  It’s onset of action is typically 1 to 2 hours after the dose is taken.  It has a short duration of approximately 4 hours and is typically dosed up to 4 times daily.

According to the drug manufacturer, Bentyl's (Dicyclomine) most common side effects include:

  • Dizziness
  • Dry mouth
  • Nausea
  • Blurred vision
  • Drowsiness
  • Nervousness
  • Weakness

Since Bentyl (Dicyclomine) an cause drowsiness, care should be taken when combining with other medications that also have the potential to cause drowsiness.  Patients should take caution before driving or when operating machinery, especially before the full effects of the medication are known.

Zyrtec (Cetirizine)

Zyrtec (Cetirizine) is a second generation antihistamine used in the treatment of allergies or urticaria (hives). While second generation antihistamines are typically non-sedating, in some patients, Zyrtec (Cetirizine) may cause drowsiness.  

The most common side effects experienced by patients taking Zyrtec (Cetirizine) include:

  • Drowsiness
  • Headache
  • Fatigue
  • Dizziness
  • Dry mouth
  • Nausea
  • Vomiting

Zyrtec (Cetirizine) is a once a day medication and its onset in action is about 1 hour.  


Bentyl (Dicyclomine) and Zyrtec (Cetirizine) can be taken together, though patients should watch for an increase in anticholinergic side effects and stop one or both of the medications if the side effects become severe.  Also, since both medications have the potential to cause drowsiness, patients should take the necessary precautions when driving or operating machinery until the full effects of both medications are known.


Ready for a more personal experience with your meds?