Cholecalciferol and Orlistat: Interaction Details
AI-assisted, pharmacist-reviewed · Source data updated Aug 9, 2026 · Sources: FDA labeling, DDInter 2.0, cited literature
Orlistat
Cholecalciferol
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
Decreased systemic cholecalciferol (vitamin D) concentrations
Interaction Deep Dive
Orlistat may reduce the levels of vitamin D (cholecalciferol)1.
Why it happens (mechanism)
Reduced vitamin D absorption
Literature reports
1 report — tap to read
a) Orlistat significantly reduced the serum levels of vitamin D (cholecalciferol) following one month of therapy in 17 obese adolescents despite vitamin supplementations. In an open-label pilot study, subjects received orlistat 120 milligrams three times daily and a daily multivitamin supplement. Individualized diets were prescribed and all subjects participated in a 12 week psychoeducational program. After one, three and six months, serum cholecalciferol levels were measured. At one month, cholecalciferol levels were reduced to 9.9 +/- 2.6 nanograms/ml (ng/ml) from a baseline of 12.7 +/- 4.4 ng/ml. Levels at three and six months were no longer significantly different from baseline. A comparison of serum levels of African-American and Caucasian subjects showed African-Americans to have a significantly lower cholecalciferol level at baseline (p less than 0.03), at one month (p less than 0.002), and six months (p less than 0.03) than Caucasians. Closer assessment of the one-month data showed that the lower vitamin D concentrations of African-Americans partially attributed to the overall results of this study 1.
Common questions
Can I take Cholecalciferol and Orlistat together?
Decreased systemic cholecalciferol (vitamin D) concentrations Always confirm with your pharmacist or prescriber before making any change.
How serious is the Cholecalciferol and Orlistat interaction?
It is rated minor. Usually limited clinical impact.
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 "probable". Good supporting evidence, though not definitively proven.
Questions for your pharmacist
- Does my dose of Cholecalciferol or Orlistat 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 (1)
- McDuffie JR, Calis KA, Booth SL, et al: Effects of orlistat on fat-soluble vitamins in obese adolescents. Pharmacotherapy 2002; 22(7):814-822. PubMed
Keep reading about Orlistat
These medications also interact with supplements
Prescription drugs aren't the whole picture — herbal and dietary supplements can interact with them too. From the evidence-graded Natural Medicines database:
major · moderate · minor — check everything you take with our drug–supplement interaction checker.
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