Relugolix and Mesoridazine: 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
Mesoridazine
No brand names on recordRelugolix
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.
Let's talk about taking mesoridazine and relugolix (Orgovyx) together. Both of these medicines can affect your heart's rhythm in a similar way. They can each stretch out a part of your heartbeat called the QT interval. When you take them together, that effect can add up, which raises the risk of a dangerous irregular heartbeat.
Because of this, these two are generally not meant to be used together. This is based on theory and how the drugs work, not on a large number of real-world reports, but it is still taken seriously. Please don't stop either one on your own. Reach out to your doctor or pharmacist, and they can help you find a safe plan.
Interaction: Additive QT interval prolongation with concurrent mesoridazine (a phenothiazine antipsychotic with well-documented QT effects) and relugolix.
- Mechanism: Additive pharmacodynamic QT prolongation; no prodrug activation involved (neither depends on the other for activity in a way that reverses direction).
- Direction/effect: Increased risk of QTc prolongation and torsades de pointes / serious ventricular arrhythmias.
- Evidence: Theoretical, but the combination is rated contraindicated.
- Onset: Unspecified.
- Management: Avoid coadministration. If exposure is unavoidable, obtain baseline and follow-up ECGs, monitor electrolytes (K+, Mg2+), and consider an alternative agent.
What happens
An increased risk of QT interval prolongation
Interaction Deep Dive
Using mesoridazine together with agents known to prolong the QT interval is contraindicated, since giving them concurrently may raise the likelihood of QT prolongation and serious ventricular arrhythmias1.
Why it happens (mechanism)
Additive QT interval prolongation
How to manage this interaction
Because both drugs can affect heart rhythm, this combination is flagged as one to avoid. Here is how a care team typically handles it:
- They may choose an alternative medication for one of the two so you are not taking both together.
- If both are truly needed, they may monitor you more closely, including heart tracings (ECGs) and blood tests for minerals like potassium and magnesium.
What you should do: keep taking both exactly as prescribed until you speak with your team. Tell your pharmacist or prescriber that you are on both, and mention any dizziness, fainting, or fluttering or pounding heartbeats right away.
Management is individual — confirm any change with your pharmacist or prescriber.
Common questions
Can I take Relugolix and Mesoridazine together?
Mesoridazine and relugolix can both prolong the QT interval, so combining them raises the risk of a dangerous heart rhythm and the pairing is considered contraindicated. Do not stop either drug on your own, but contact your prescriber or pharmacist promptly about a safer option. Always confirm with your pharmacist or prescriber before making any change.
How serious is the Relugolix and Mesoridazine interaction?
It is rated contraindicated. These should generally not be used together.
How quickly could this interaction happen?
The documented onset is "unspecified". The timing of this interaction is not well characterized.
How is the Relugolix and Mesoridazine interaction managed?
Because both drugs can affect heart rhythm, this combination is flagged as one to avoid. Here is how a care team typically handles it: They may choose an alternative medication for one of the two so you are not taking both together. If both are truly needed, they may monitor you more closely, including heart tracings (ECGs) and blood tests for minerals like potassium and magnesium. What you should… 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 Relugolix or Mesoridazine 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 a safer alternative to one of these medications for me?
References (1)
- Product Information: SERENTIL(R) oral tablets, injection, oral solution, mesoridazine besylate oral tablets, injection, oral solution. Boehringer Ingelheim Pharmaceuticals,Inc, Ridgefield, CT, 2001.
Keep reading about Mesoridazine
Keep reading about Relugolix
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