The purpose of this pilot study is to prepare for a larger study that will compare the effectiveness and safety of two common pain medications, ibuprofen and acetaminophen, to help treat period cramps in women with Crohn's disease. The goal of this study is to identify any challenges in running a larger study. The investigators will track how many people sign up for the study, how well participants follow the study plan, how many people stay in the study, and whether they are able to complete all the study activities, such as taking the medication, submitting samples, and filling out surveys.

During the study, participants will undergo a screening visit that includes a blood draw, physical exam, pregnancy test, stool testing, and complete surveys about Crohn's disease and menstrual cycles. Once this visit is complete, the rest of the study will occur at home.

Participants will be assigned to take either ibuprofen or acetaminophen to help treat period cramps for four menstrual cycles in a row. Participants will take ibuprofen for two cycles and acetaminophen for two cycles. Participants will know which medication is being taken at any given time, but the order in which they take the medications will be randomly assigned.

Before each menstrual cycle, participants will submit a stool sample and fill out a short (<1 minute) electronic survey. When participants develop period cramps, they will take the assigned medication for three days and fill out short (<1 minute) electronic surveys about their cramps. After participants finish taking the medication for three days, they will submit another stool sample and fill out two more short (<1 minute) electronic surveys. After have completing this process for four menstrual cycles, a remote interview with a researcher to give feedback on the study will be conducted.

Inclusion Criteria:

• Ages 18-44 years
• Assigned female at birth
• Crohn's Disease (CD) diagnosis
• In stable clinical remission from CD, defined as a short Crohn's Disease Activity Index (CDAI; See Table 3) <150 without use of corticosteroids
• Self-reported primary dysmenorrhea
• Regular menstrual cycles occurring every 23-35 days
• Using an appropriate contraceptive method or abstinence

Exclusion Criteria:

• Any of the following conditions: endometriosis, adenomyosis, polycystic ovarian syndrome, endometrial fibroids/polyps, chronic pelvic inflammatory disease, a history of pelvic surgery including hysterectomy, any other pathological pelvic conditions, or current pregnancy
• Plans to become pregnant during the study period
• Use of an oral contraceptive for less than 3 months, on an unstable oral contraceptive dose within the last 3 months, switched from one oral contraceptive to another within the last 3 months or intend to do so during the course of the trial
• Taking hormone therapy including estrogen or progesterone that is not part of a hormonal contraceptive
• Known hypersensitivity or contraindication to ibuprofen or acetaminophen
• Inability to complete REDCap questionnaires (including confusion despite training and/or lack of smart phone and/or computer access).
• Not able to speak and read English language.

Deidentified individual data that supports the results will be shared beginning 9 to 36 months following publication provided the investigator who proposes to use the data has approval from an Institutional Review Board (IRB), Independent Ethics Committee (IEC), or Research Ethics Board (REB), as applicable, and executes a data use/sharing agreement with the University of North Carolina.

beginning 9 and continuing for 36 months following publication

Investigator who proposes to use the data has approved IRB, IEC, or REB and an executed data use/sharing agreement with the University of North Carolina.