Silodosin and Cyclosporine Injection: Interaction Details
AI-assisted, pharmacist-reviewed · Source data updated Aug 8, 2026 · Sources: FDA labeling, DDInter 2.0, cited literature
Silodosin
Cyclosporine Injection
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.
What happens
Increased silodosin concentration
Interaction Deep Dive
In vitro studies indicate that silodosin is a P-glycoprotein (P-gp) substrate. The combination of cycloSPORINE and silodosin may lead to increased silodosin concentrations due to inhibition of P-glycoprotein (P-gp) modulated efflux of silodosin by cycloSPORINE, a strong P-gp inhibitor. A significant increase in silodosin exposure was noted in drug interaction studies with ketoconazole, a CYP3A4 inhibitor which also inhibits P-gp. Concomitant use of cycloSPORINE and silodosin is not recommended1. If silodosin and cycloSPORINE are coadministered, monitor patients for increased silodosin adverse effects such as postural hypotension, dizziness, syncope, headache, and retrograde ejaculation.
Why it happens (mechanism)
Inhibition of P-glycoprotein modulated efflux of silodosin by cycloSPORINE
Common questions
Can I take Silodosin and Cyclosporine Injection together?
Increased silodosin concentration Always confirm with your pharmacist or prescriber before making any change.
How serious is the Silodosin and Cyclosporine Injection 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 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 Silodosin or Cyclosporine Injection 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: RAPAFLO(TM) oral capsules, silodosin oral capsules. Watson Pharma, Morristown, NJ, 2008. DailyMed
Keep reading about Silodosin
Keep reading about Cyclosporine Injection
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Prescription drugs aren't the whole picture — herbal and dietary supplements can interact with them too. From the evidence-graded Natural Medicines database:
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