The main purpose of this study is to determine the effect of LY3871801 when administered orally on the levels of methotrexate (part 1), drug cocktail (warfarin, dextromethorphan, and midazolam) and repaglinide (part 2) in the blood stream when administered orally in healthy participants. The information about any adverse effects experienced will be collected and the tolerability of LY3871801 will also be evaluated. The study may last up to approximately 25 days for each participant.

Inclusion Criteria:

• Participants who are overtly healthy as determined by medical evaluation including medical history and physical examination.
• Have body weight ≥ 45 kilograms (kg) and body mass index (BMI) within the range 18.5 to 40.0 kilograms per meter squared (kg/m²)
• Male or female participants not of childbearing potential (both parts) and for part 2, female participants of child bearing potential are eligible.

Exclusion Criteria:

• Have known allergies to LY3871801, related compounds, or any components of the formulation, or history of significant atopy.
• Have known allergies to drugs including methotrexate, folic acid, repaglinide, warfarin, dextromethorphan, and midazolam that would pose an unacceptable risk to the participant.
• Have an abnormal blood pressure and/or pulse rate, deemed to be clinically significant by the investigator
• Have used or intend to use prescription or nonprescription medication
• Have a positive (not indeterminate) QuantiFERON®-TB Gold test