Ulipristal and Trospium / Xanomeline: Interaction Details
AI-assisted, pharmacist-reviewed · AI content regenerated Jul 11, 2026 · Source data updated Jul 2, 2026 · Sources: FDA labeling, DDInter 2.0, cited literature
Ulipristal
Trospium / Xanomeline
How we grade severity & evidence
Severity levels
- Contraindicated: These should generally not be used together.
- Major: Potentially serious — often needs a change or close monitoring.
- Moderate: Can be significant — usually manageable with monitoring.
- Minor: Usually limited clinical impact.
Evidence grades
- Established: Well documented — supported by controlled studies or strong clinical data.
- Probable: Good supporting evidence, though not definitively proven.
- Suspected: Some evidence suggests this interaction, but it is not well established.
- Possible: Limited or conflicting evidence; the interaction may occur.
- Theoretical: Predicted from the drugs' pharmacology; not yet confirmed in people.
Ratings come from the documented interaction literature and are reviewed by a pharmacist. They describe the documented risk of the combination, not what will necessarily happen to you — your dose, timing, and health picture all matter.
Here's what's going on with Ella (ulipristal) and Cobenfy (which contains xanomeline). Your body uses an enzyme called CYP3A4 to break down ulipristal. Xanomeline can briefly slow that enzyme down in your gut. That means a little more ulipristal may stay in your system, which could make its side effects (like headache, nausea, belly pain, or tender breasts) feel a bit stronger or more common.
I want to reassure you that this is a theoretical concern, meaning it's based on how the drugs work rather than lots of real-world reports. It's usually manageable. Just let your pharmacist or doctor know you take both so they can keep an eye on how you feel.
Effect: Xanomeline (in Cobenfy) transiently inhibits intestinal CYP3A4, potentially increasing exposure (AUC/Cmax) of oral sensitive CYP3A4 substrates. Ulipristal is a CYP3A4 substrate, so its exposure may rise, increasing the frequency/severity of substrate-related adverse effects.
- Mechanism: Local gut CYP3A4 inhibition (not systemic).
- Direction: Increased ulipristal exposure/effect (ulipristal is active drug, not a prodrug requiring CYP3A4 activation).
- Onset: Unspecified.
- Evidence: Theoretical.
- Severity: Moderate.
Management: Monitor for increased ulipristal adverse effects (headache, nausea, abdominal/pelvic pain, dysmenorrhea). Dose may be individualized by the care team if clinically warranted.
What happens
Increased oral sensitive CYP3A4 substrate exposure and an increased risk on severity and frequency of sensitive CYP3A4 substrate-related adverse reactions
Interaction Deep Dive
In the gut, xanomeline produces a temporary local inhibition of CYP3A4, though this effect does not occur systemically. When xanomeline is taken alongside oral medications that are sensitive substrates of CYP3A4, the exposure to those oral sensitive CYP3A4 substrates may rise. As a result, adverse reactions associated with these substrates could occur more often and/or become more severe. Should the two be administered together, patients should be watched for any increase in the frequency and/or severity of adverse reactions linked to oral drugs that are sensitive substrates of CYP3A41.
Why it happens (mechanism)
Inhibition of CYP3A4-substrate metabolism by xanomeline
How to manage this interaction
Good news: this is usually straightforward for your care team to handle.
- Keep taking both exactly as prescribed unless your doctor or pharmacist tells you otherwise.
- Your team may simply watch you more closely for stronger or more frequent ulipristal side effects, such as headache, nausea, stomach or pelvic pain, or breast tenderness.
- If side effects show up, dosing may be adjusted and individualized by your care team.
- Tell your pharmacist or prescriber that you take both drugs, and report any new or bothersome symptoms.
Management is individual — confirm any change with your pharmacist or prescriber.
Common questions
Can I take Ulipristal and Trospium / Xanomeline together?
Xanomeline (in Cobenfy) may modestly raise ulipristal (Ella) levels by briefly slowing gut CYP3A4, which could increase side effects; this is a theoretical concern, so keep taking both as prescribed and let your pharmacist or doctor know so they can monitor you. Always confirm with your pharmacist or prescriber before making any change.
How serious is the Ulipristal and Trospium / Xanomeline interaction?
It is rated moderate. Can be significant — usually manageable with monitoring.
How quickly could this interaction happen?
The documented onset is "unspecified". The timing of this interaction is not well characterized.
How is the Ulipristal and Trospium / Xanomeline interaction managed?
Good news: this is usually straightforward for your care team to handle. Keep taking both exactly as prescribed unless your doctor or pharmacist tells you otherwise. Your team may simply watch you more closely for stronger or more frequent ulipristal side effects, such as headache, nausea, stomach or pelvic pain, or breast tenderness. If side effects show up, dosing may be adjusted and individuali… Management is individual — always follow your own care team's guidance.
How strong is the evidence for this interaction?
The evidence is graded "theoretical". Predicted from the drugs' pharmacology; not yet confirmed in people.
Questions for your pharmacist
- Does my dose of Ulipristal or Trospium / Xanomeline need adjusting while I take them together?
- What symptoms should prompt me to call you or my prescriber right away?
- Does the timing of my doses matter for this combination?
- Is there anything you'd monitor while I'm on both?
References (1)
- Citation #1
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