Drug & supplement interaction

Glycerol + Orlistat

Orlistat brand names: Xenical, Alli.

No Known Interaction
The bottom line No known interaction

We found no known interaction between Glycerol 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

Glycerol 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 Glycerol 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 Glycerol 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.

Glycerol safety at a glance

Glycerol overall Use caution Generally well tolerated in normal amounts, but large oral doses can cause stomach upset and dehydration concerns.
Pregnancy Use caution Topical and food-amount use is likely fine, but talk to your doctor before using medicinal doses.
Breastfeeding Use caution Little specific safety data exists, so check with your doctor before using larger medicinal amounts.

Safety guidance is general; always confirm with your pharmacist or doctor for your situation.

Still wondering about combining Orlistat and Glycerol? Ask Dr. Brian Staiger, PharmD, BCPS directly ›
What to actually watch for

No Interaction Found — But Data Suggests Glycerol 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. One of them is worth acting on rather than waiting out — marked below.

  • Hives Worth acting on Additional detail

    Glycerol

    “Topically, glycerol has been reported to cause burning, irritation, and pruritus. Rectally, the regular administration of glycerol 50% enemas has been reported to cause generalized urticaria in at least two patients; in both patients, symptoms resolved after discontinuation.”

    Glycerol · Natural Medicines adverse-effect record, reported in pruritus.

    4 sources cited
    1. 93754. Balaskas E, Szepietowski JC, Bessis D, Ioannides D, Ponticelli C, Ghienne C, Taberly A, Dupuy P. Randomized, double-blind study with glycerol and paraffin in uremic xerosis. Clin J Am Soc Nephrol. 2011 Apr;6(4):748-52. PubMed
    2. 93756. Blanchet-Bardon C, Tadini G, Machado Matos M, Delarue A. Association of glycerol and paraffin in the treatment of ichthyosis in children: an international, multicentric, randomized, controlled, double-blind study. J Eur Acad Dermatol Venereol. 2012 Aug;26 PubMed
    3. 110019. Kajita N, Kanamori K, Yamamoto S, Yoshida K. Generalized Urticaria Caused by a Glycerin Enema in an Infant. J Investig Allergol Clin Immunol 2022;32(4):318-319. PubMed
    4. 110025. Suzuki R, Fukuyama K, Miyazaki Y, Namiki T. Contact urticaria syndrome and protein contact dermatitis caused by glycerin enema. JAAD Case Reports. 2016;2:108-10. PubMed

    Orlistat

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

  • Bloating or gas / Diarrhea / Vomiting / Nausea reported in 7.6% of FDA reports for Orlistat Additional detail

    Glycerol

    “Orally, glycerol can cause bloating, nausea, vomiting, thirst, and diarrhea (15,2475).”

    Glycerol · Natural Medicines adverse-effect record, reported in diarrhea.

    2 sources cited
    1. 15. McEvoy GK, ed. AHFS Drug Information. Bethesda, MD: American Society of Health-System Pharmacists, 1998.
    2. 2475. Wagner DR. Hyperhydrating with glycerol: implications for athletic performance. J Am Diet Assoc 1999;99:207-12. 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 Additional detail

    Glycerol

    Recorded for Glycerol in the same Natural Medicines adverse-effect record shown under Bloating or gas / Diarrhea / Vomiting / Nausea above.

    Orlistat

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

  • Dizziness / Headache Additional detail

    Glycerol

    “Orally, glycerol can cause mild headache and dizziness (15,2475).”

    Glycerol · Natural Medicines adverse-effect record, reported in cluster headache.

    2 sources cited
    1. 15. McEvoy GK, ed. AHFS Drug Information. Bethesda, MD: American Society of Health-System Pharmacists, 1998.
    2. 2475. Wagner DR. Hyperhydrating with glycerol: implications for athletic performance. J Am Diet Assoc 1999;99:207-12. PubMed

    Orlistat

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

Reported for Glycerol but not commonly for Orlistat: a stroke or mini-stroke and increased thirst.

Effects for Orlistat come from the ADVERSE REACTIONS section of its FDA label; effects for Glycerol 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.

Everything else you take

See Every Supplement That Interacts With Orlistat

This page covers Glycerol 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 Glycerol as Part of a Dietary Supplement Product? Check It for Interactions

We hold 775 real supplement products containing Glycerol, each one broken down to its full ingredient list — and combination products often carry several ingredients besides Glycerol. Even though Glycerol 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 Glycerol 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 Glycerol
Top 25%

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

29 days ago today
Medication Orlistat
Top half

#896 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 Glycerol reference on this page ↓
  • Freshness: we automatically re-check this combination every week — this pair was last verified September 20, 2026. The Glycerol 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 Glycerol

What is Glycerol?

Glycerol
  • Constipation (laxative)
  • Dry skin (moisturizer)
  • Dry, irritated eyes
  • Sore throat (in lozenges)
  • Athletic hydration and endurance
  • Cough and chest congestion (in some syrups)

Glycerol (glycerin) is a sweet, syrupy compound made naturally in the body and widely used in foods, skin products, and medicines. It is well established as a laxative and a skin and eye moisturizer, while its use to boost athletic performance is less proven and is banned in sports because it can mask other substances. For most people it is well tolerated, but check with a pharmacist before using it medicinally, especially if you are pregnant, breastfeeding, or have a health condition.

Not applicable (a simple chemical compound, also made naturally in the body) · Oral liquid, syrup, rectal suppositories, enemas, eye drops, skin creams and lotions, throat lozenges, sports drinks

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

Glycerol: dosing

There is no single "standard" dose of glycerol because it depends entirely on the product and the reason for use. A glycerin suppository for constipation, an oral laxative solution, an eye drop, and a sports hydration drink all use very different amounts.The safest approach is to follow the directions on the product label or your healthcare provider's instructions.

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

Read the full Glycerol 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 & Glycerol

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

0Major
0Moderate
0Minor
2,829No known interaction
No interaction 2,829 drugs checked — show the list
Evidence & sources

Glycerol References

The 8 references that drive our Glycerol 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. McEvoy GK, ed. AHFS Drug Information. Bethesda, MD: American Society of Health-System Pharmacists, 1998.
  2. Wagner DR. Hyperhydrating with glycerol: implications for athletic performance. J Am Diet Assoc 1999;99:207-12. PubMed
  3. Yu YL, Kumana CR, Lauder IJ, et al. Treatment of acute cortical infarct with intravenous glycerol. A double-blind, placebo-controlled randomized trial. Stroke 1993;24:1119-24. PubMed
  4. Frei A, Cottier C, Wunderlich P, Ludin E. Glycerol and dextran combined in the therapy of acute stroke. A placebo-controlled, double-blind trial with a planned interim analysis. Stroke 1987;18:373-9. PubMed
  5. Balaskas E, Szepietowski JC, Bessis D, Ioannides D, Ponticelli C, Ghienne C, Taberly A, Dupuy P. Randomized, double-blind study with glycerol and paraffin in uremic xerosis. Clin J Am Soc Nephrol. 2011 Apr;6(4):748-52. PubMed
  6. Blanchet-Bardon C, Tadini G, Machado Matos M, Delarue A. Association of glycerol and paraffin in the treatment of ichthyosis in children: an international, multicentric, randomized, controlled, double-blind study. J Eur Acad Dermatol Venereol. 2012 Aug;26 PubMed
  7. Kajita N, Kanamori K, Yamamoto S, Yoshida K. Generalized Urticaria Caused by a Glycerin Enema in an Infant. J Investig Allergol Clin Immunol 2022;32(4):318-319. PubMed
  8. Suzuki R, Fukuyama K, Miyazaki Y, Namiki T. Contact urticaria syndrome and protein contact dermatitis caused by glycerin enema. JAAD Case Reports. 2016;2:108-10. 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 Glycerol and Orlistat Together: Common Questions

Is it safe to take Glycerol with Orlistat?
We do not list a known interaction between Glycerol 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 Glycerol and Orlistat have any of the same side effects?
Yes — our sources link each of them separately to 8 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.
Does Orlistat interact with any supplements?
Yes. Orlistat has documented interactions with 18 supplements in our database — Glycerol 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

Still Have a Question About Orlistat and Glycerol?

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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.