Orlistat and Nadroparin: Interaction Details
AI-assisted, pharmacist-reviewed · Source data updated Aug 9, 2026 · Sources: FDA labeling, DDInter 2.0, cited literature
Orlistat
Nadroparin
No brand names on record
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
An increased risk of bleeding
Interaction Deep Dive
Concomitant use of orlistat and anticoagulants reports of decreased prothrombin, increased INR and unbalanced anticoagulant treatment resulting in change of hemostatic parameters. Vitamin K absorption may be reduced with orlistat. if coadministered, closely monitor patients on chronic stable doses of anticoagulants for changes in coagulation parameters1. Orlistat may reduce the absorption of fat-soluble vitamins including vitamin K, with the result that a lower dose of warfarin is required 3. The pharmacokinetics and pharmacodynamics of a single dose of warfarin were not altered by a 10 day pretreatment of orlistat 2.
Why it happens (mechanism)
Changes in hemostatic parameters
Literature reports
2 reports — tap to read
a) In a randomized, crossover study, 12 healthy male volunteers received 30 mg of warfarin on the eleventh day of orlistat (120 mg 3 times daily for 16 days) or placebo therapy. Warfarin was administered on day 11 with the morning orlistat or placebo dose, following an overnight fast. Participants were studied in a controlled environment for 144 hours following the warfarin dose. There were no differences between the pharmacokinetic parameters of R- and S- warfarin with respect to the AUC, Cmax, or Tmax for either the orlistat or placebo dosing. In addition, prothrombin time (PT) and Factor VII values were no different for either orlistat or placebo dosing 2.
b) Orlistat may reduce the absorption of fat-soluble vitamins including vitamin K, with the result that a lower dose of warfarin is required. A 66-year-old white male with a 3-year history of chronic atrial fibrillation, for which he had been taking warfarin for 2.5 years was seen for follow-up. He was taking amlodipine and perindopril for hypertension, and his type 2 diabetes mellitus was diet-controlled. Orlistat 120 mg 3 times daily was initiated for weight reduction. Eighteen days after the introduction of orlistat his INR was increased at 4.7. His INR had been previously stable for greater than 1 year. The amount of fatty foods was reduced but no other changes were made. His warfarin was withheld for 2 days and restarted at 5 mg/day. His International Normalized Ration (INR) remained elevated (4.4). Warfarin was withheld for another 2 days and subsequently restarted at 3 mg/day. Satisfactory control of INR was eventually obtained. The Naranjo score indicated that this suspected adverse reaction was probable 3.
Common questions
Can I take Orlistat and Nadroparin together?
An increased risk of bleeding Always confirm with your pharmacist or prescriber before making any change.
How serious is the Orlistat and Nadroparin 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 Orlistat or Nadroparin 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 (3)
- Product Information: XENICAL oral capsules, orlistat oral capsules. H2-Pharma, LLC (per Dailymed), Montgomery, AL, 2023. DailyMed
- Zhi J, Melia AT, Guerciolini R, et al: The effect of orlistat on the pharmacokinetics and pharmacodynamics of warfarin in healthy volunteers. J Clin Pharmacol 1996; 36:659-666. DOI
- MacWalter R, Fraser H, & Armstrong K: Orlistat enhances warfarin effect. Ann Pharmacother 2003; 37:510-512. PubMed
Keep reading about Orlistat
Keep reading about Nadroparin
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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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