Succinylcholine and Levonorgestrel Intrauterine System: Interaction Details
AI-assisted, pharmacist-reviewed · Source data updated Aug 8, 2026 · Sources: FDA labeling, DDInter 2.0, cited literature
Levonorgestrel Intrauterine System
Succinylcholine
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
Prolongation of neuromuscular blockade
Interaction Deep Dive
The chronic use of oral contraceptives has been reported to reduced plasma cholinesterase activity by approximately 20%1. Plasma cholinesterase rapidly hydrolyzes succinylcholine to succinylmonocholine, which possesses insignificant muscle relaxant properties. By reducing the activity of plasma cholinesterase, the neuromuscular blocking effect of succinylcholine may be enhanced 2. The enhanced response to succinylcholine may be more pronounced in patients who have a pathologically depressed cholinesterase activity.
Why it happens (mechanism)
Inhibition of plasma cholinesterase activity
Common questions
Can I take Succinylcholine and Levonorgestrel Intrauterine System together?
Prolongation of neuromuscular blockade Always confirm with your pharmacist or prescriber before making any change.
How serious is the Succinylcholine and Levonorgestrel Intrauterine System interaction?
It is rated moderate. Can be significant — usually manageable with monitoring.
How quickly could this interaction happen?
The documented onset is "delayed". Effects tend to build up gradually over days to weeks.
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 Succinylcholine or Levonorgestrel Intrauterine System 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 (2)
- Durant NN & Katz RL: Suxamethonium. Br J Anaesth 1982; 54:195-208.
- Product Information: Anectine(R), succinylcholine. Glaxo Wellcome Inc. Research Triangle Park, NC, 1999. DailyMed
Keep reading about Levonorgestrel Intrauterine System
Keep reading about Succinylcholine
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