Daclatasvir and Relugolix: 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
Daclatasvir
Relugolix
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. Daclatasvir (Daklinza) can block a 'pump' in your body called P-gp that normally helps move relugolix (Orgovyx) out of your system. When that pump is slowed down, more relugolix stays in your body than usual. In one study with a similar pump-blocking drug, relugolix levels roughly tripled.
Higher levels can mean a higher chance of relugolix side effects like hot flashes, fatigue, or increased blood pressure. The good news is your care team can manage this by spacing the doses apart and keeping a closer eye on you. Please don't stop or change either medicine on your own. Just talk with your pharmacist or doctor so they can plan the safest approach for you.
Mechanism: Daclatasvir inhibits P-gp-mediated efflux of relugolix (a P-gp substrate), reducing relugolix clearance and increasing its systemic exposure. Neither drug is a prodrug here; the interaction is a straightforward increase in relugolix effect.
- Direction/magnitude: Increased relugolix AUC and Cmax. A study with erythromycin (P-gp inhibitor) showed 3.5-fold AUC and 2.9-fold Cmax increases.
- Evidence: Probable; severity major.
- Management: Avoid coadministration if possible. If unavoidable, give relugolix first, separate by at least 6 hours, and monitor for adverse reactions more frequently. Relugolix may be interrupted up to 2 weeks for short P-gp inhibitor courses; if held greater than 7 days, restart with 360 mg loading dose then 120 mg daily.
What happens
Increased relugolix exposure
Interaction Deep Dive
Concurrent administration of relugolix (which is a P-gp substrate) with P-gp inhibitors should be avoided, since doing so can raise relugolix exposure and thereby heighten the likelihood of adverse reactions linked to relugolix. When coadministration cannot be avoided, give relugolix or relugolix/estradiol/norethindrone acetate first, allow a minimum of 6 hours between doses, and increase the frequency of monitoring for adverse reactions12. Relugolix therapy may be paused for up to 2 weeks to accommodate a brief course of certain P-gp inhibitors. Once the P-gp inhibitor has been stopped, resume relugolix. Should relugolix be interrupted for more than 7 days, restart it with a 360 mg loading dose on the first day, followed by 120 mg once daily thereafter. In a drug interaction study, giving relugolix (P-gp substrate) together with erythromycin (P-gp inhibitor) raised relugolix AUC and Cmax by 3.5-fold and 2.9-fold, respectively1.
Why it happens (mechanism)
Inhibition of P-gp-mediated efflux transport of relugolix
How to manage this interaction
What your care team may do:
- Avoid using the two together when possible, since combining them can raise relugolix levels.
- If both are needed, they may have you take relugolix first and separate the doses by at least 6 hours.
- They may monitor you more closely for relugolix side effects.
- For a short course of daclatasvir, they may pause relugolix and resume it afterward, using a loading dose if it was stopped for more than 7 days.
What you should do: Keep taking both exactly as prescribed for now, and ask your pharmacist or prescriber how they want to time or adjust your doses. Report any new or worsening side effects.
Management is individual — confirm any change with your pharmacist or prescriber.
Literature reports
1 report — tap to read
a) In a drug interaction study, giving relugolix (a P-gp substrate) together with erythromycin (a P-gp inhibitor) raised the AUC of relugolix by 3.5-fold and its Cmax by 2.9-fold 1.
Common questions
Can I take Daclatasvir and Relugolix together?
Daclatasvir can raise relugolix levels and side effect risk by blocking a drug-transport pump, so your care team may avoid the combination, separate the doses by at least 6 hours, or monitor you more closely. Do not change either medicine on your own. Always confirm with your pharmacist or prescriber before making any change.
How serious is the Daclatasvir and Relugolix interaction?
It is rated major. Potentially serious — often needs a change or close monitoring.
How quickly could this interaction happen?
The documented onset is "unspecified". The timing of this interaction is not well characterized.
How is the Daclatasvir and Relugolix interaction managed?
What your care team may do: Avoid using the two together when possible, since combining them can raise relugolix levels. If both are needed, they may have you take relugolix first and separate the doses by at least 6 hours. They may monitor you more closely for relugolix side effects. For a short course of daclatasvir, they may pause relugolix and resume it afterward, using a loading dose if it wa… Management is individual — always follow your own care team's guidance.
How strong is the evidence for this interaction?
The evidence is graded "probable". Good supporting evidence, though not definitively proven.
Questions for your pharmacist
- Does my dose of Daclatasvir or Relugolix 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 (2)
- Product Information: ORGOVYX oral tablets, relugolix oral tablets. Sumitomo Pharma America, Inc (per FDA), Marlborough, MA, 2025. DailyMed
- Product Information: MYFEMBREE(R) oral tablets, relugolix, estradiol, norethindrone acetate oral tablets. Myovant Sciences Inc (per FDA), Brisbane, CA, 2021. DailyMed
Keep reading about Daclatasvir
Keep reading about Relugolix
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