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Dietary supplement

L-Glutamine + FOS Powder Ingredients & Drug Interactions

by Douglas Laboratories

L-Glutamine + FOS Powder label
See full label image
Powder Category: Botanical With Nutrients
Most serious interaction: Moderate
Clinical methodology reviewed by · Updated Sep 16, 2026 · Label data from the NIH DSLD
What is this page for?

First and foremost: checking L-Glutamine + FOS Powder against your medications. The heart of this page is the interaction checker and the full interaction report — how this product’s ingredients may interact with prescription and over-the-counter medicines you may be taking.

Around that, we add a pharmacist’s high-level view of the product as a whole — what’s inside, the evidence for its stated use, how transparent the label is, and what safety data exists — so you can see the full picture in one place. It’s educational information from our licensed clinical databases and the clinical staff at HelloPharmacist — not medical advice — and we don’t sell or endorse products. Our editorial policy

The interaction bottom line Most serious interaction: Moderate

L-Glutamine + FOS Powder is a dietary supplement by Douglas Laboratories with 2 active ingredients. Its ingredients are commonly taken for muscle recovery and sports performance, gut health and 'leaky gut', recovery from severe illness or injury.Based on those ingredients, 50 medications have a known interaction with it, the most serious rated moderate. The ingredients most likely to interact are L-Glutamine. Use the checker below to test your specific medication, or read the full HelloPharmacist Interaction Report.

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Check Your Meds Against L-Glutamine + FOS Powder by Douglas Laboratories

Ask about any prescription or over-the-counter medication and we check it for interactions with L-Glutamine + FOS Powder by Douglas Laboratories — and tell you which ingredient is responsible.

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HelloPharmacist Scorecard of L-Glutamine + FOS Powder by Douglas Laboratories

Our pharmacy team’s full take, with four database checks built into the cards below — a summary of what is known, not a grade of the product itself.

From our pharmacy team — supplement deep dive

Generated from HelloPharmacist’s pharmacist-curated databases and editorial rules · Last generated Aug 13, 2026

What’s inside

Full disclosure
Ingredient Transparency · database check
Full

Every active ingredient lists its own amount on the label.

Why this rating?
  • The label discloses an exact amount for 2 of its 2 active ingredients.
  • No proprietary blends here — you can verify the dose of every single component.

This powder contains 2 active ingredients. L-Glutamine is an amino acid — a building block your body uses to repair tissue, support immune function, and fuel your gut lining.

It's the same form your body makes naturally. FOS (fructooligosaccharides) is a prebiotic fiber that feeds the helpful bacteria in your digestive tract.

The product contains no inactive fillers or binders.

Does it work?

Strong evidence
Evidence for Intended Use · database check
By FDA rules, dietary supplements can’t claim to treat, cure, or prevent disease — so labels speak in careful marketing language. We discern each product’s intended use from its name, label claims, and label statements, then grade the clinical evidence for that use. How these ratings are computed

This product doesn't appear to be marketed for a specific use, so we graded Glutamine's overall clinical evidence instead.

Strong

Strong clinical evidence supports Glutamine for:

Why this rating?
  • We looked at the product name, claims, and label statements and couldn't find a stated purpose to grade.
  • Since the label doesn't commit to one use, we graded the ingredient's overall clinical evidence instead.
  • On file: Sickle cell disease — rated "Effective" (Natural Medicines).
  • On file: HIV/AIDS-related wasting — rated "Possibly Effective" (Natural Medicines).
  • On file: Critical illness (trauma) — rated "Possibly Effective" (Natural Medicines).
  • On file: Postoperative recovery — rated "Possibly Effective" (Natural Medicines).
  • On file: Pancreatitis — rated "Possibly Effective" (Natural Medicines).

L-Glutamine is rated effective for sickle cell disease. It's rated possibly effective for HIV/AIDS-related wasting, postoperative recovery, and critical illness from trauma.

We hold no established effectiveness data in our system for FOS in this product.

The evidence, ingredient by ingredient Glutamine

How safe is it?

Well-documented data
Safety Information · database check
Well characterized

Adverse-effect, pregnancy, and general safety data are on file for most of these ingredients.

Why this rating?
  • We hold adverse-effect (side-effect) data for 1 of the 1 matched ingredient.
  • Pregnancy & breastfeeding safety ratings cover 1 of 1.
  • General safety write-ups exist for 1 of 1.
  • Remember: this measures how much safety information exists. Thin data is not the same as being safe.

L-Glutamine is generally well tolerated in healthy adults. However, people with kidney or liver disease should use it only under medical supervision.

Oral side effects reported in studies include belching, bloating, constipation, diarrhea, flatulence, stomach pain, headache, muscle pain, nausea, and vomiting — most common at high doses (10–30 grams daily). A few rare cases of dizziness, mania, or hypomania have been reported in people with bipolar disorder.

The product is rated likely safe in pregnancy, but there isn't enough reliable safety data to know if it's safe while breastfeeding — talk with your doctor or pharmacist if you're nursing or planning to breastfeed.

Side effects, ingredient by ingredient Glutamine

Meds to double-check

Moderate interaction found
Known Interaction Concern · database check
Moderate identified

The most serious documented interaction for these ingredients is Moderate. Check your medications for a personalized result.

Why this rating?
  • 1 of the 1 matched ingredient can interact with medications — Glutamine.
  • The most serious interaction on file is rated Moderate.
  • Some involve high-stakes drug classes: seizure medications.
  • For scale: 50 individual medications appear in the full list. A big number alone doesn't make a product dangerous — what matters is whether YOUR medication is on it, so run yours through the interaction checker on this page.

Moderate concern with anticonvulsants (seizure medications) — glutamine might theoretically work against them, though this hasn't been seen in actual patients. If you take any seizure medication, check with your doctor or pharmacist before adding this product.

Check your own medication Run your meds through the checker above

The bottom line

Scorecard at a glanceFully disclosed formula with strong clinical evidence behind its ingredients' uses. Moderate medication interactions have been identified, and safety information is well characterized.

This product may help with sickle cell disease or support recovery after surgery or critical illness, though the evidence for the latter two is still building. If you take seizure medication, check with your doctor or pharmacist before starting it.

If you have kidney or liver disease, get medical supervision before using it. Talk it over with your own doctor or pharmacist to see if it fits your situation.

Educational only — not medical advice; always confirm with your pharmacist. Our editorial policy · How we use AI

Assessment coverage: 1 of 2 active ingredients matched to our full ingredient reviews (monographs). Based on the product label dated Feb 26, 2014.

This Scorecard evaluates available label information, ingredient evidence, and known medication-safety considerations. It does not independently verify product identity, purity, potency, contamination, or manufacturing quality. How these ratings are computed

At a glance

General information

Key facts about L-Glutamine + FOS Powder, straight from the product label.

Brand Douglas Laboratories
Barcode (UPC) 310539018606
Net contents 250 Gram(s)
Market status On market
Date entered into DSLD Feb 26, 2014
DSLD ID 30650
Product type Botanical With Nutrients
Supplement form Powder
Dietary claims / uses All Other
Intended target group(s) Adult (18 - 50 Years), Dairy Free, Sugar Free
From the label
Everything in this section is reproduced from the manufacturer’s own product label — it’s the label speaking, not HelloPharmacist. We show it so you can see exactly what the maker states; we don’t verify or endorse those statements.

Supplement Facts

The label details for L-Glutamine + FOS Powder by Douglas Laboratories, sourced from the NIH Dietary Supplement Label Database.

Supplement Facts

Daily Value (DV) Target Group(s):
Adults and children 4 or more years of age
Minimum serving Sizes:
1 tsp
Maximum serving Sizes:
1 tsp
Servings per container
62
UPC/BARCODE
310539018606
IngredientAmount% DV
Total Carbohydrates1.5 Gram(s)1%
L-Glutamine2.5 Gram(s)--
FOS1.5 Gram(s)--

Tap any ingredient to jump to its full detail below.

Label statements
These statements are the manufacturer’s wording, reproduced from the product label — the label is saying it, not HelloPharmacist. We don’t verify or endorse them.
Formulation

This product contains NO yeast, soy protein, milk/dairy, corn, sodium, sugar, starch, artificial coloring, preservatives or flavoring.

Suggested/Recommended/Usage/Directions

Suggested Usage: As a dietary supplement, adults mix 1 teaspoon (approx. 4 grams) in water or juice, twice daily or as directed by physician.

Precautions

KEEP OUT OF REACH OF CHILDREN.

Tamper resistant package, do not use if outer seal is missing.

Storage

For optimal storage conditions, store in a cool, dry place. (59(0)-77(0)F/15(0)-25(0)C) (35-65% relative humidity)

General

Formula #80697

FDA Statement of Identity

A Dietary Supplement

Is this label outdated? Report a formula or label change and our pharmacy team will review it.

See for yourself

L-Glutamine + FOS Powder by Douglas Laboratories label

The label scan from the NIH Dietary Supplement Label Database. Tap to enlarge.

L-Glutamine + FOS Powder label

Label images are published by the NIH Dietary Supplement Label Database for the version of this product on file. Always read your actual product label.

View the full label (PDF)
What’s inside

The Ingredients in L-Glutamine + FOS Powder by Douglas Laboratories

These are the 2 active ingredients this product is made of. Select any to open its full monograph.

Serving size1 tsp Dosage formPowder Servings per container62 Amounts shown are per serving.

Most supplement products combine several ingredients, and a medication can interact with the product through any one of them. Each ingredient below shows whether it has known drug interactions.

L-Glutamine

Interacts with
50 drugs
2.5 Gram(s) per serving

Glutamine is the most abundant amino acid in the body and is usually made in your muscles. A prescription form is FDA-approved to help reduce sickle c...

L-Glutamine monograph & interactions

FOS

1.5 Gram(s) per serving
Interaction report

L-Glutamine + FOS Powder by Douglas Laboratories Drug Interactions

Want to check YOUR meds against L-Glutamine + FOS Powder?

Ask about interactions with your drugs in plain English — “Can I take it with lisinopril?” — and we find you the answer in seconds, ingredient by ingredient.

 Go to the checker
50Drugs
50 Moderate

Ingredients driving the most interactions

L-Glutamine 50

Individual Drug Interactions

The ingredients in L-Glutamine + FOS Powder interact with 50 drugs. Click any drug to see the details.

1 of the 2 ingredients in L-Glutamine + FOS Powder interact with drugs. Each result below shows which ingredient is responsible. L-Glutamine

Each ingredient & the kinds of drugs it affects

For each ingredient in L-Glutamine + FOS Powder with known interactions, here are the types of medications it can affect. Open any type for the detail — or search your exact drug in the checker above.

L-Glutamine1 drug type · 50 drugs

Anticonvulsants

Theoretically, glutamine might antagonize the effects of anticonvulsant medications.
Glutamine is metabolized to the excitatory neurotransmitter glutamate. Glutamate might have antagonistic effects with anticonvulsant drugs. However, this interaction has not yet been reported in humans.

Likelihood Possible Evidence D
L-Glutamine full monograph & interactions
The maker

Brand information

Manufacturer and brand details for L-Glutamine + FOS Powder, from the product label.

Douglas Laboratories

See all Douglas Laboratories products
Name
Douglas Laboratories
Street Address
600 Boyce Road
City
Pittsburgh
State
PA
ZipCode
15205
Phone Number
1.800.245.4440
Web Address
www.douglaslabs.com
Pharmacist Counseling Corner

L-Glutamine + FOS Powder by Douglas Laboratories: Common Questions

Does L-Glutamine + FOS Powder by Douglas Laboratories interact with any medications?
Yes. Based on its ingredients, L-Glutamine + FOS Powder has a known interaction with 50 medications. Use the checker to see how it interacts with a specific drug.
How can one product interact with so many drugs?
L-Glutamine + FOS Powder contains 2 active ingredients, and an interaction can come from any of them. We check every ingredient, combine the results into one list per medication, and show which ingredient and mechanism is responsible.
Where does this information come from?
The product label data comes from the NIH Dietary Supplement Label Database (DSLD); the interaction data is built on the Natural Medicines database and reviewed by HelloPharmacist pharmacists.
What's the difference between L-glutamine and regular glutamine?
L-glutamine is the form your body produces and uses naturally. It's the active form, so that's what you'll see in supplements like this one.
What does FOS do in this product?
FOS is a prebiotic fiber that feeds the beneficial bacteria living in your gut, helping them thrive and support digestion. We don't have established effectiveness data in our system for FOS specifically.
What side effects should I watch for?
Most commonly, people report stomach issues — bloating, gas, constipation, or diarrhea — especially at higher doses. Headache, nausea, and muscle pain have also been reported. If symptoms don't ease or you feel dizzy, lower your dose and talk with your pharmacist.
Can I take this if I'm pregnant or nursing?
L-Glutamine is rated likely safe in pregnancy. For breastfeeding, there isn't enough reliable safety data to know either way — talk with your doctor or pharmacist for personalized advice if you're nursing.
Is this safe if I have kidney or liver problems?
People with kidney or liver disease should only use this supplement under medical supervision. Your doctor or pharmacist can tell you whether it's right for your situation and at what dose.
Does this product contain any fillers or binders?
No — this powder contains only the two active ingredients: L-glutamine and FOS.

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

Not sure if L-Glutamine + FOS Powder is safe with your meds?

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Label information is sourced from the NIH Dietary Supplement Label Database and reflects the product version on file; always read your actual product label. This page is for education only and is not a substitute for professional medical advice. Confirm with your pharmacist or doctor before combining supplements and medications.

L-Glutamine + FOS Powder label
Go deeper

The Full Monographs Behind L-Glutamine + FOS Powder’s Ingredients

Every ingredient we hold a full HelloPharmacist monograph for — uses, evidence, safety, and the complete interaction list.

Herb & supplement monograph

Glutamine

Interacts with 50 drugs

Glutamine is the most abundant amino acid in the body and is usually made in your muscles. A prescription form is FDA-approved to help reduce sickle cell disease complications, but for most...

Read the full Glutamine monograph →
Sources

Sources & How We Checked

L-Glutamine + FOS Powder's label data comes from the NIH Dietary Supplement Label Database; the ingredient interaction data is from the Natural Medicines database, reviewed by our pharmacists.

Content is written and reviewed by licensed HelloPharmacist pharmacists. See our data sources and editorial standards for how this information is built and checked.

The 11 references behind this product’s interaction data

Every citation that drives the interaction findings for this product’s ingredients, from the evidence-graded Natural Medicines (TRC Healthcare) database. Open an ingredient to browse its citations — links open the study on PubMed or the publisher’s site.

Glutamine 11 references
  1. Miller AL. Therapeutic considerations of L-glutamine: a review of the literature. Altern Med Rev 1999;4:239-48..
  2. Bozzetti F, Biganzoli L, Gavazzi C, et al. Glutamine supplementation in cancer patients receiving chemotherapy: a double-blind randomized study. Nutrition 1997;13:748-51.. PubMed
  3. Mebane AH. L-Glutamine and mania. Am J Psychiatry 984;141:1302-3.
  4. Meldrum BS. Glutamate as a neurotransmitter in the brain: review of physiology and pathology. J Nutr 2000;130:1007S-15S.. PubMed
  5. Garlick PJ. Assessment of the safety of glutamine and other amino acids. J Nutr 2001;131:2556S-61S.. PubMed
  6. Chapman AG. Glutamate and epilepsy. J Nutr 2000;130:1043S-5S.. PubMed
  7. Ziegler TR. Glutamine supplementation in cancer patients receiving bone marrow transplantation and high dose chemotherapy. J Nutr 2001;131:2578S-84S.. PubMed
  8. Laviano A, Molfino A, Lacaria MT, Canelli A, De Leo S, Preziosa I, Rossi Fanelli F. Glutamine supplementation favors weight loss in nondieting obese female patients. A pilot study. Eur J Clin Nutr. 2014 Nov;68(11):1264-6. PubMed
  9. Endari (l-glutamine) [package insert]. Torrance, CA: Emmaus Medical,Inc; 2017.
  10. Niihara Y, Miller ST, Kanter J, et al. A Phase 3 Trial of l-Glutamine in Sickle Cell Disease. N Engl J Med 2018;379(3):226-35. doi: 10.1056/NEJMoa1715971.
  11. Ogden HB, Child RB, Fallowfield JL, et al. Gastrointestinal Tolerance of Low, Medium and High Dose Acute Oral l-Glutamine Supplementation in Healthy Adults: A Pilot Study. Nutrients. 2020;12(10):2953. PubMed

See these in context on the Glutamine monograph →

Parts of this content are provided by the Therapeutic Research Center, LLC.

DISCLAIMER: Currently this does not check for drug-drug interactions. This is not an all-inclusive comprehensive list of potential interactions and is for informational purposes only. Not all interactions are known or well-reported in the scientific literature, and new interactions are continually being reported. Input is needed from a qualified healthcare provider including a pharmacist before starting any therapy. Application of clinical judgment is necessary.

© 2021 Therapeutic Research Center, LLC

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