Drug & supplement interaction

Oats + Orlistat

Orlistat brand names: Xenical, Alli.

No Known Interaction
Medically reviewed by · Updated July 2026 · Pair last verified Sep 20, 2026
The bottom line No known interaction

We found no known interaction between Oats 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.

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Interaction report

Oats 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 Oats 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.

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.

Oats safety at a glance

Oats overall Generally safe Oats as a food are safe for most people when eaten as part of a normal diet.
Pregnancy Likely Safe When used orally in food amounts. Read the full pregnancy detail
Breastfeeding Likely Safe When used orally in food amounts. Read the full breastfeeding detail

Pregnancy & breastfeeding ratings are from Natural Medicines (Therapeutic Research Center) — the full detail is in the Special populations card below. Safety guidance is general; always confirm with your pharmacist or doctor for your situation.

Still wondering about combining Orlistat and Oats? Ask Dr. Brian Staiger, PharmD, BCPS directly ›
How we checked

Why No Interaction Is Listed for Orlistat

Interactions in our licensed database are recorded against drug classes, not just single drug names. Orlistat is filed under 2 classifications — including oral drugs. Oats has documented interactions with 2 drug classes — the most serious being antidiabetes drugs (moderate) and insulin (moderate) — and none of Orlistat’s classifications are among them.

Classification data comes from our licensed Natural Medicines dataset. A medication can belong to classes beyond those recorded there, so this describes how the check was run — it is not a safety guarantee.

Keep it in perspective

Oats Does Interact With Other Medications

Oats has 86 moderate known drug interactions in our database — Orlistat isn’t one of them. If you take anything else, check it against the full list below.

Moderate 86 No known interaction 2,744 (incl. Orlistat)
Taking anything else?

Check Another of Your Medications Against Oats

Covers the 2,830 medications we’ve checked against Oats. Pick one to open its full report.

What to actually watch for

No Interaction Found — But Data Suggests Oats and Orlistat May Share Several of the Same Side Effects

This is not an interaction. Neither one changes how your body handles the other, and nothing here says they react together. What our sources do show is that each has separately been linked to the effects below — so taking both can make those effects more likely to turn up, and harder to pin on one or the other if they do. 3 of them are worth acting on rather than waiting out — marked below.

  • A severe allergic reaction / Hives / An allergic reaction Worth acting on Additional detail

    Oats

    “In a case report, a 45-year-old male developed acute generalized urticaria, facial angioedema, and dyspnea immediately after consuming oat flour. The reaction resolved after emergency care for anaphylaxis. Further investigation revealed an IgE-mediated hypersensitivity reaction to oat proteins.”

    Oats · Natural Medicines adverse-effect record, reported in urticaria.

    1 source cited
    1. 113490. González-Afonso M, Cañas JA, Sastre B, et al. A Case of Anaphylaxis After Ingestion of Oats: Research Into New Allergens. J Investig Allergol Clin Immunol 2022;32(6):506-508. PubMed

    Orlistat

    Listed in the ADVERSE REACTIONS section of the FDA label for Orlistat. Read the label on DailyMed ›

  • Bloating or gas reported in 6.3% of FDA reports for Orlistat Additional detail

    Oats

    “When consumed orally, oats provide fiber. Increasing fiber in the diet can cause flatulence, bloating, abdominal distention, and unpleasant taste. To minimize side effects, doses should be slowly titrated to the desired level.”

    Oats · Natural Medicines adverse-effect record, reported in flatulence.

    3 sources cited
    1. 12514. Lembo A, Camilleri M. Chronic constipation. N Engl J Med 2003;349:1360-8. . PubMed
    2. 4979. Cooper SG, Tracey EJ. Small-bowel obstruction caused by oat-bran bezoar. N Engl J Med 1989;320:1148-9. DOI
    3. 4985. Rosario PG, Gerst PH, Prakash K, Albu E. Dentureless distention: oat bran bezoars cause obstruction. J Am Geriatr Soc 1990;38:608. PubMed

    Orlistat

    Listed in the ADVERSE REACTIONS section of the FDA label for Orlistat, and in voluntary FDA adverse-event reports. Read the label on DailyMed ›

  • Itching / A skin rash Additional detail

    Oats

    “Topically, oat-containing preparations can cause contact dermatitis. Redness, burning, and itchiness have also been reported.”

    Oats · Natural Medicines adverse-effect record, reported in dermatitis.

    2 sources cited
    1. 12515. De Paz Arranz S, Perez Montero A, Remon LZ, Molero MI. Allergic contact urticaria to oatmeal. Allergy 2002;57:1215. . PubMed
    2. 103340. Sobhan M, Hojati M, Vafaie SY, Ahmadimoghaddam D, Mohammadi Y, Mehrpooya M. The efficacy of colloidal oatmeal cream 1% as add-on therapy in the management of chronic irritant hand eczema: A double-blind study. Clin Cosmet Investig Dermatol. 2020;13:241-25

    Orlistat

    Listed in the ADVERSE REACTIONS section of the FDA label for Orlistat. Read the label on DailyMed ›

Reported for Oats but not commonly for Orlistat: a bowel blockage and shortness of breath.

Effects for Orlistat come from the ADVERSE REACTIONS section of its FDA label; effects for Oats come from the Natural Medicines adverse-effect record, quoted above. Where a percentage is shown, it is the share of 25,755 voluntary FDA FAERS reports for Orlistat that mention that effect — a reporting proportion, not an incidence rate and not evidence the drug caused it. Wording is matched across sources by our own clinical vocabulary, so treat this as a prompt to pay attention, not a diagnosis.

Special populations

Oats in Pregnancy & Breastfeeding

Pregnancy And Lactation Likely Safe

When used orally in food amounts.

DISCLAIMER: This tool is intended for informational purposes only, and should not be interpreted as specific medical advice. Patients should consult with a qualified healthcare provider before making decisions about therapies and/or health conditions.© 2026 Therapeutic Research Center

Overlapping uses

What Orlistat Is Prescribed For, and What Oats 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. Oats 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.

Oats has been studied for:

  • Dyslipidemia Natural Medicines rates the evidence for Oats: Likely Effective Read what the research shows

    Oats for dyslipidemia

    A diet rich in soluble fiber, such as that found in oats, can reduce cholesterol by a moderate amount.

  • Diabetes Natural Medicines rates the evidence for Oats: Possibly Effective Read what the research shows

    Oats for diabetes

    A diet rich in whole grains, such as oats, may help prevent diabetes or improve blood glucose control in patients with type 1, type 2, or gestational diabetes.

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 Oats for the same health topic, tell your prescriber, especially if the medicine is being adjusted to a target.

Everything else you take

See Every Supplement That Interacts With Orlistat

This page covers Oats 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

Open the Orlistat interaction page

One more smart check

Taking Oats as Part of a Dietary Supplement Product? Check It for Interactions

We hold 2,183 real supplement products containing Oats, each one broken down to its full ingredient list — and combination products often carry several ingredients besides Oats. Even though Oats 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:

How much people look this up

Where Oats 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.

Supplement Oats
Top 10%

#135 of 1,452 supplements looked up here in the last 7 days

29 days ago today
Medication Orlistat
Top 25%

#519 of 2,830 medications looked up here in the last 7 days

29 days ago today

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 Oats reference on this page ↓
  • Freshness: we automatically re-check this combination every week — this pair was last verified September 20, 2026. The Oats 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.
Data structure & sourcing designed and verified by .
Supplement

About Oats

What is Oats?

  • Lowering cholesterol
  • Heart and digestive health
  • Soothing itchy or irritated skin
  • Blood sugar support
  • Anxiety and stress (oat straw, traditional)

Oats are a well-studied whole grain whose soluble fiber (beta-glucan) can help lower cholesterol and support heart health when eaten regularly. As a food, oats are safe for most people, and colloidal oatmeal is widely used to soothe skin. Evidence for oat straw supplements (for anxiety, energy, or focus) is much weaker.

Avena sativa · Poaceae · Seeds (oat grain), oat bran, and the green tops/straw (oat straw) · Oatmeal and whole grains, oat bran, colloidal oatmeal (topical), capsules, tinctures, and teas (oat straw)

An interaction check asks whether these two react with each other — it does not ask whether Oats is a good idea for someone in your situation. Here is what our Oats record says about it on its own.

Oats: dosing

There is no single standardized dose for oats, and the right amount depends on the form and your goal. For cholesterol benefits, public health guidance generally points to getting a few grams of oat beta-glucan per day from foods like oatmeal and oat bran, spread across meals.For supplements, teas, or oat straw products, there is no well-established dose, so follow the directions on the product label. Topical colloidal oatmeal products should be used as directed on the package.

From our Oats monograph — the full record covers uses, side effects and every documented interaction.

Read the full Oats monograph & all interactions
Medication

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.

Rectal discharge 2,434 reports
Gastrointestinal disorder 2,186 reports
Constipation 1,991 reports
Diarrhea 1,960 reports
Weight increased 1,944 reports
See full Orlistat drug information
Keep checking

Other Drugs & Oats

Browse every other medication we’ve checked against Oats — both the ones with a known interaction and the ones without. Select any drug for the full detail.

0Major
86Moderate
0Minor
2,743No known interaction
86 Moderate 2,743 No interaction
Moderate

86 interactions

Showing 60 of 86 moderate interactions — see all 86 on the Oats page.

No interaction 2,743 drugs checked — show the list

We also checked Oats against these medications and found no known interaction in our sources. Open any page to confirm.

Showing the 60 most looked-up of 2,743 medications checked with no known interaction — see the full Oats list.

See the full Oats interactions page
See every supplement checked against Orlistat, ranked by severity
Evidence & sources

Oats References

The 13 references that drive our Oats 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.

  1. Cooper SG, Tracey EJ. Small-bowel obstruction caused by oat-bran bezoar. N Engl J Med 1989;320:1148-9. DOI
  2. Pick ME, Hawrysh ZJ, Gee MI, et al. Oat bran concentrate bread products improve long-term control of diabetes: a pilot study. J Am Diet Assoc 1996;96:1254-61. PubMed
  3. Braaten JT, Scott FW, Wood PJ, et al. High beta-glucan oat bran and oat gum reduce postprandial blood glucose and insulin in subjects with and without type 2 diabetes. Diabet Med 1994;11:312-8.
  4. Rosario PG, Gerst PH, Prakash K, Albu E. Dentureless distention: oat bran bezoars cause obstruction. J Am Geriatr Soc 1990;38:608. PubMed
  5. Food and Drug Administration. Food labeling: health claims: oats and coronary heart disease. Fed Regist 1996;61:296-313.
  6. Foulke J. FDA Allows Whole Oat Foods To Make Health Claim on Reducing the Risk of Heart Disease. FDA Talk Paper. 1997. Available at: http://www.fda.gov/bbs/topics/ANSWERS/ANS00782.html.
  7. Chandalia M, Garg A, Lutjohann D, et al. Beneficial effects of high dietary fiber intake in patients with type 2 diabetes mellitus. N Engl J Med 2000;342:1392-8. PubMed
  8. Lembo A, Camilleri M. Chronic constipation. N Engl J Med 2003;349:1360-8. . PubMed
  9. De Paz Arranz S, Perez Montero A, Remon LZ, Molero MI. Allergic contact urticaria to oatmeal. Allergy 2002;57:1215. . PubMed
  10. Delgado G, Kleber ME, Krämer BK, et al. Dietary intervention with oatmeal in patients with uncontrolled type 2 diabetes mellitus - A crossover study. Exp Clin Endocrinol Diabetes. 2019;127(9):623-629. PubMed
  11. Sobhan M, Hojati M, Vafaie SY, Ahmadimoghaddam D, Mohammadi Y, Mehrpooya M. The efficacy of colloidal oatmeal cream 1% as add-on therapy in the management of chronic irritant hand eczema: A double-blind study. Clin Cosmet Investig Dermatol. 2020;13:241-25
  12. Hou Q, Li Y, Li L, Cheng G, Sun X, Li S, Tian H. The metabolic effects of oats intake in patients with type 2 diabetes: A systematic review and meta-analysis. Nutrients. 2015;7(12):10369-87. PubMed
  13. González-Afonso M, Cañas JA, Sastre B, et al. A Case of Anaphylaxis After Ingestion of Oats: Research Into New Allergens. J Investig Allergol Clin Immunol 2022;32(6):506-508. 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.

Pharmacist Counseling Corner

Taking Oats and Orlistat Together: Common Questions

Is it safe to take Oats with Orlistat?
We do not list a known interaction between Oats and Orlistat. That does not guarantee the combination is risk-free, so confirm with your pharmacist or doctor — especially if you take other medications or have a health condition.
Do Oats and Orlistat have any of the same side effects?
Yes — our sources link each of them separately to 6 of the same effects. That is not an interaction: neither changes how your body handles the other. It does mean that if one of those effects turns up, it can be harder to tell which one is behind it. They are listed on this page with the source behind each.
Are Oats and Orlistat used for the same thing?
They overlap in purpose, which usually means the real question is whether you need both rather than whether they are safe together. This page lists the shared uses and how strong the evidence is for Oats in each. That is a conversation for your prescriber, especially if Orlistat is being adjusted to a target.
How was the Oats and Orlistat combination checked?
Interactions in our licensed database are recorded against drug classes. Orlistat is filed under 2 classifications, and Oats has documented interactions with 2 drug classes — none of Orlistat's classifications are among them. A medication can belong to classes beyond those recorded in our dataset, so this describes how the check was run rather than guaranteeing safety.
Does Oats interact with any other medications?
Yes. Oats has 86 documented drug interactions in our database — Orlistat is simply not one of them. If you take anything else, it is worth checking each one; they are all listed on this page.
Does Orlistat interact with any supplements?
Yes. Orlistat has documented interactions with 18 supplements in our database — Oats is not one of them. The Orlistat interaction page linked on this page lists every one, ranked by severity.

Written and reviewed by the HelloPharmacist editorial staff. Our editorial policy

Where next

Keep Exploring

Oats monograph Uses, safety profile, and every drug interaction in one place Orlistat drug information The full plain-English guide to this medication Orlistat supplement interactions Every supplement checked against Orlistat, ranked by severity Supplement interaction checker Check any supplement or product against your medications Browse medications A–Z Every drug we’ve checked against herbs & supplements References The 13 citations behind this page Ask a pharmacist Free, personal answer from our licensed team

Still Have a Question About Orlistat and Oats?

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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.