Peppermint Oil for Urinary Retention

The purpose of the study is to determine if the use of peppermint oil among postpartum women experiencing urinary retention will increase spontaneous urination and decrease the need for catheterization. A randomized controlled study will be conducted, with two arms. Subjects will be randomized into one of the two following arms:

* Arm 1: Subjects will be exposed to vapor of peppermint oil
* Arm 2: Subjects will be exposed to vapor of placebo (mineral oil) Outcome variables include resolution of urinary retention, time to spontaneous urination, volume of spontaneous urination, frequency of urinary catheterization, and patient satisfaction.

• Peppermint oil vapors (Other): Subjects will be exposed to vapor of peppermint oil
• Mineral Oil (Other): Subjects will be exposed to vapor of placebo (mineral oil)

Primary outcomes

• Percent of Patients With Urinary Retention Resolved [10 minutes]: Urinary retention defined as: * More than 6 hours after delivery or foley catheter removal without being able to spontaneously void * Symptomatic urinary retention without being able to spontaneously void * Change in fundal height or position without being able to spontaneously void More than 6 hours after delivery or foley catheter removal without voiding spontaneously; symptomatic urinary retention without being able to spontaneously void; or change in fundal height or position without being able to spontaneously void Resolution of urinary retention will be achieved if patient spontaneously voids within 10 minutes after exposure to oil

Secondary outcomes

• Time to Spontaneous Urination [1 hour]: Minutes until participant spontaneously voids
• Volume of Spontaneous Urination [1 hour]: Volume of urine when participant spontaneously voids
• Incidence of Urinary Catheterization [1 hour]: Whether participant requires urinary catheterization or not
• Patient Satisfaction [1 hour]: Patient rated satisfaction

Sex: Female, ages: 18 Years to any, accepts healthy volunteers

Inclusion Criteria:

* 1\. 18 years old or older 2. English speaking 3. Admitted to Bethesda North Mom Baby Unit 4. Postpartum 5. Experiencing urinary retention - defined as meeting at least one of the following criteria:

  * More than 6 hours after delivery or foley catheter removal without being able to spontaneously void
  * Symptomatic urinary retention without being able to spontaneously void
  * Change in fundal height or position without being able to spontaneously void 6. Bladder scan showing bladder containing 400mL or more urine

Exclusion Criteria:

1. Allergy to peppermint
2. Asthma
3. Active herpes lesions
4. Seizure disorder
5. Not able to void in toilet (ex: requiring use of bed pan to void)

Participant flow

Outcome results

• Percent of Patients With Urinary Retention Resolved (Primary), Count of participants, Participants: Peppermint Oil 3; Placebo 1
• Time to Spontaneous Urination (Secondary)
• Volume of Spontaneous Urination (Secondary)
• Incidence of Urinary Catheterization (Secondary)
• Patient Satisfaction (Secondary)

Adverse events

Time frame: from enrollment until end of follow-up, up to 2 days

• Study Protocol and Statistical Analysis Plan (PDF, 2025-08-12)