Fructo-oligosaccharides (fos) + Orlistat
Orlistat brand names: Xenical, Alli.
We found no known interaction between Fructo-oligosaccharides (fos) and Orlistat in our sources. Absence of a documented interaction is not the same as proven safety, and does not guarantee one does not exist. Do not start, stop, or change a medication or supplement based on this page; confirm with your pharmacist or doctor first. Additionally, although there is no interaction, the two are separately associated with some of the same side effects, which would make a new symptom harder to attribute to one or the other.
Fructo-oligosaccharides (fos) and Orlistat
We checked these two against our interaction database. Here is what we found.
No Known Interaction Found
We did not find a documented interaction between Orlistat and Fructo-oligosaccharides (fos) in our sources. This does not guarantee that the combination is completely free of risk — there is often limited research on supplements and herbal products, especially around drug interactions.
Worth understanding: our licensed dataset holds no drug-interaction record for Fructo-oligosaccharides (fos) at all — not against Orlistat, and not against any other medication we track. This verdict therefore rests on the absence of any recorded data, not on research that looked at this combination and found nothing. We cannot rule an interaction out.
If you decide to take both, the practical routine is simple: add one new thing at a time and note the date you started it. If the combination is going to disagree with you, it usually shows in the first days to a couple of weeks — and a start date turns “I’ve been feeling off” into something a pharmacist can actually work with. Do not stop a prescribed medicine on your own.
Always talk with your pharmacist or doctor before making changes to your medications or supplements, particularly if you take several medications or have an ongoing health condition.
Fructo-oligosaccharides (fos) safety at a glance
Safety guidance is general; always confirm with your pharmacist or doctor for your situation.
What Orlistat Is Prescribed For, and What Fructo-oligosaccharides (fos) Has Been Studied For
These two come up together because they touch the same health topic — not because they do the same job. Orlistat is a prescription medicine with approved uses on its FDA label. Fructo-oligosaccharides (fos) is a supplement: what follows is what researchers have looked at it for, and how strong that evidence is.
Orlistat is prescribed for: Xenical and prescription-strength orlistat are approved to help obese adults lose weight and keep it off when used with a reduced-calorie diet. They are intended for people with a body mass index (BMI) of 30 or higher, or 27 or higher if other risk factors such as high blood pressure, diabetes, or dyslipidemia (abnormal cholesterol or fat levels in the blood) are present. Alli is the over-the-counter version, approved for weight loss in overweight adults 18 and older when used with a reduced-calorie, low-fat diet and exercise program.
Fructo-oligosaccharides (fos) has been studied for:
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Diabetes studied, not established Fructo-oligosaccharides (fos) has been studied for this. Natural Medicines rates the evidence: Insufficient Reliable Evidence To Rate Read what the research shows
Fructo-oligosaccharides (fos) for diabetes
Oral FOS has only been evaluated in combination with probiotics; its effect when used alone is unclear.
Effectiveness ratings and the research summaries above are the verbatim record from the Natural Medicines database, which grades evidence from “Effective” down to “Insufficient Reliable Evidence To Rate”. A rating below the top of that scale means researchers have looked at it — not that it works, and never that it can stand in for a prescribed medicine. Do not stop or replace Orlistat on your own; if you are taking Fructo-oligosaccharides (fos) for the same health topic, tell your prescriber, especially if the medicine is being adjusted to a target.
See Every Supplement That Interacts With Orlistat
This page covers Fructo-oligosaccharides (fos) only. If you take other supplements — a multivitamin, a sleep aid, something for joints — the Orlistat page lists 18 supplements it has a documented interaction with, worst first, each one explained.
The most serious there right now: Activated Charcoal (major), Coffee Charcoal (moderate), European Mandrake (moderate), Fish Oil (moderate) and Glucomannan (moderate).
By severity: 1 major · 8 moderate · 9 minor.
From our pharmacist’s overview on the Orlistat page
“People who take Orlistat (Xenical, Alli) for weight loss often browse the very supplement aisle where fiber products and fish oil sit, and both show up on this page, so it deserves genuine attention before you mix anything in. Nearly all 18 ingredients on file can change how oral medications absorb from the gut, and the single major-ra…”
Reviewed by 2 · Jul 18, 2026
Taking Fructo-oligosaccharides (fos) as Part of a Dietary Supplement Product? Check It for Interactions
We hold 1,251 real supplement products containing Fructo-oligosaccharides (fos), each one broken down to its full ingredient list — and combination products often carry several ingredients besides Fructo-oligosaccharides (fos). Even though Fructo-oligosaccharides (fos) itself has no known interaction with Orlistat, another ingredient on your label might. Find your product and we’ll check every ingredient on its label:
Where Fructo-oligosaccharides (fos) and Orlistat Sit Against Everything Else
Out of every supplement and medication people look up on HelloPharmacist, here is where these two land this week — and which way each has been moving.
#223 of 1,452 supplements looked up here in the last 7 days
#243 of 2,830 medications looked up here in the last 7 days
Position among everything looked up on this site, not a measure of how commonly either one is used or how important it is. A supplement can climb this list because of a news story. It counts every request to the page, automated ones included, and nothing here identifies anyone.
Where does our data come from?
- Source: the Natural Medicines (TRC Healthcare) clinical database — the evidence-graded professional reference for herb & supplement interactions.
- Citation library: 103,510 references behind our interaction content, 65,311 of them resolved to verified PubMed/DOI sources. See every Fructo-oligosaccharides (fos) reference on this page ↓
- Freshness: we automatically re-check this combination every week — this pair was last verified September 20, 2026. The Fructo-oligosaccharides (fos) and Orlistat records this page draws on were last updated July 10, 2026.
- What “no known interaction” means: no documented interaction in the sources above — not a guarantee of safety. Supplements are studied far less than prescription drugs, so we say exactly what the evidence supports, and nothing more.
About Fructo-oligosaccharides (fos)
What is Fructo-oligosaccharides (fos)?
- Digestive and gut health
- Prebiotic to support good bacteria
- Constipation relief
- Calcium absorption support
- Blood sugar and appetite support
Fructo-oligosaccharides (FOS) are a type of soluble fiber that acts as a prebiotic, meaning they feed the helpful bacteria in your gut. They are generally considered safe for most people in normal food amounts, but higher doses commonly cause gas and bloating. Evidence for many health claims is still limited, so talk with your pharmacist or doctor before using FOS supplements.
Carbohydrate fibers extracted from plants such as chicory root, or made by enzymatic processing of sugars · Powders, capsules, syrups, added to foods and infant formulas, and combined with probiotics in synbiotic products
An interaction check asks whether these two react with each other — it does not ask whether Fructo-oligosaccharides (fos) is a good idea for someone in your situation. Here is what our Fructo-oligosaccharides (fos) record says about it on its own.
Fructo-oligosaccharides (fos): dosing
There is no single official or standardized dose of FOS. Amounts used in studies and products vary widely, often given as a few grams of fiber per day.Because higher amounts increase the risk of gas and bloating, it is best to start low and increase gradually if needed.
From our Fructo-oligosaccharides (fos) monograph — the full record covers uses, side effects and every documented interaction.
About Orlistat
What Is Orlistat Used For?
Brand names: Xenical, Alli
Xenical and prescription-strength orlistat are approved to help obese adults lose weight and keep it off when used with a reduced-calorie diet. They are intended for people with a body mass index (BMI) of 30 or higher, or 27 or higher if other risk factors such as high blood pressure, diabetes, or dyslipidemia (abnormal cholesterol or fat levels in the blood) are present.
Alli is the over-the-counter version, approved for weight loss in overweight adults 18 and older when used with a reduced-calorie, low-fat diet and exercise program.
Most-Reported Side Effects for Orlistat
From FAERS, the FDA’s public side-effect reporting system (25,755 reports, all brands). Reports are voluntary and are not proof the drug caused the effect.
Other Drugs & Fructo-oligosaccharides (fos)
Browse every other medication we’ve checked against Fructo-oligosaccharides (fos) — both the ones with a known interaction and the ones without. Select any drug for the full detail.
No drugs match “”.
No interaction 2,829 drugs checked — show the list
We also checked Fructo-oligosaccharides (fos) against these medications and found no known interaction in our sources. Open any page to confirm.
- Apixaban ›
- Levothyroxine ›
- Amlodipine ›
- Warfarin ›
- Methylphenidate ›
- Sertraline ›
- Testosterone ›
- Losartan Potassium ›
- Ivermectin ›
- Metoprolol ›
- Aspirin ›
- Rivaroxaban ›
- Acetaminophen ›
- Rosuvastatin ›
- Abemaciclib ›
- Escitalopram ›
- Clopidogrel ›
- Tadalafil ›
- Atorvastatin ›
- Docusate ›
- Tirzepatide ›
- Ibuprofen ›
- Hydroxyurea ›
- Valacyclovir ›
- Methamphetamine ›
- Warfarin Sodium ›
- Semaglutide ›
- Sumatriptan ›
- Prednisone ›
- Lisdexamfetamine ›
- Propranolol ›
- Metformin ›
- Amoxicillin ›
- Lisinopril ›
- Amitriptyline ›
- Bupropion ›
- Methotrexate ›
- Bendamustine ›
- Amphetamine ›
- Acyclovir ›
- Isotretinoin ›
- Doxycycline ›
- Fluoxetine ›
- Pregabalin ›
- Amlodipine Besylate ›
- Lamotrigine ›
- Azithromycin ›
- Gabapentin ›
- Acetaminophen, Codeine ›
- Dextroamphetamine ›
- Clonazepam ›
- Quetiapine ›
- Methylene Blue ›
- Omeprazole ›
- Letrozole ›
- Naproxen ›
- Duloxetine ›
- Buspirone ›
- Citalopram ›
- Ciprofloxacin ›
Showing the 60 most looked-up of 2,829 medications checked with no known interaction — see the full Fructo-oligosaccharides (fos) list.
Fructo-oligosaccharides (fos) References
The 6 references that drive our Fructo-oligosaccharides (fos) monograph and interaction data, from the evidence-graded Natural Medicines (TRC Healthcare) database. Citations with a link open the study on PubMed or the publisher’s site.
- Briet F, et al. Symptomatic response to varying levels of fructo-oligosaccharides consumed occasionally or regularly. Eur J Clin Nutr 1995;49:501-7.
- Bouhnik Y, Vahedi K, Achour L, et al. Short-chain fructo-oligosaccharide administration dose-dependently increases fecal bifidobacteria in healthy humans. J Nutr 1999;129:113-6. PubMed
- Cummings JH, Macfarlane GT, Englyst HN. Prebiotic digestion and fermentation. Am J Clin Nutr 2001;73:415S-420S. PubMed
- Souza DDS, Tahan S, Weber TK, Araujo-Filho HB, de Morais MB. Randomized, double-blind, placebo-controlled parallel clinical trial assessing the effect of fructooligosaccharides in infants with constipation. Nutrients. 2018;10(11). pii: E1602. PubMed
- Andermann TM, Fouladi F, Tamburini FB, et al. A Fructo-Oligosaccharide Prebiotic Is Well Tolerated in Adults Undergoing Allogeneic Hematopoietic Stem Cell Transplantation: A Phase I Dose-Escalation Trial. Transplant Cell Ther 2021;27(11):932. PubMed
- Dou Y, Yu X, Luo Y, Chen B, Ma D, Zhu J. Effect of Fructooligosaccharides Supplementation on the Gut Microbiota in Human: A Systematic Review and Meta-Analysis. Nutrients 2022;14(16):3298. PubMed
Medication overviews come from MedlinePlus (NIH); supplement label data from the NIH Dietary Supplement Label Database. Content is written and reviewed by licensed HelloPharmacist pharmacists — see our data sources and editorial standards.
Orlistat Is Linked to Lower Levels of 5 Nutrients
Natural Medicines records Orlistat as a medicine that can lower these. This is not an interaction with Fructo-oligosaccharides (fos) — it is a separate effect of the medicine, and it is a reason some people are advised to supplement rather than to avoid one:
Read the full Orlistat nutrient depletion report ›
Depletion records come from the licensed Natural Medicines database. Do not start a supplement on the strength of this page — ask your pharmacist or doctor whether it applies to you.
Taking Fructo-oligosaccharides (fos) and Orlistat Together: Common Questions
Is it safe to take Fructo-oligosaccharides (fos) with Orlistat?
Do Fructo-oligosaccharides (fos) and Orlistat have any of the same side effects?
Are Fructo-oligosaccharides (fos) and Orlistat used for the same thing?
Does Orlistat interact with any supplements?
Written and reviewed by the HelloPharmacist editorial staff. Our editorial policy
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This information is for education only and is not a substitute for professional medical advice. Always check with your pharmacist or doctor before starting, stopping, or combining supplements and medications.