Drug & supplement interaction

Gamma-linolenic Acid (gla) + Methylnaltrexone

Methylnaltrexone brand name: Relistor.

No Known Interaction
Medically reviewed by · Updated July 2026 · Pair last verified Sep 13, 2026
The bottom line No known interaction

We found no known interaction between Gamma-linolenic Acid (gla) and Methylnaltrexone 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 label for Methylnaltrexone states a food rule worth keeping to, and 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

Gamma-linolenic Acid (gla) and Methylnaltrexone

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 Methylnaltrexone and Gamma-linolenic Acid (gla) 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.

Gamma-linolenic Acid (gla) safety at a glance

Gamma-linolenic Ac... overall Use caution Usually well tolerated, but quality and source of the oil matter and some people have side effects.
Pregnancy Avoid Not enough safety data; some sources are traditionally avoided in pregnancy, so it is best to avoid.
Breastfeeding Use caution Safety is not well established, so check with your doctor before use.

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

Still wondering about combining Methylnaltrexone and Gamma-linolenic Acid (gla)? Ask Dr. Brian Staiger, PharmD, BCPS directly ›
How we checked

Why No Interaction Is Listed for Methylnaltrexone

Interactions in our licensed database are recorded against drug classes, not just single drug names. Methylnaltrexone is filed under a single classification — cytochrome p450 2d6 (cyp2d6) inhibitors. Gamma-linolenic Acid (gla) has documented interactions with 1 drug class — the most serious being anticoagulant/antiplatelet drugs (moderate) — and none of Methylnaltrexone’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

Gamma-linolenic Acid (gla) Does Interact With Other Medications

Gamma-linolenic Acid (gla) has 122 moderate known drug interactions in our database — Methylnaltrexone isn’t one of them. If you take anything else, check it against the full list below.

Moderate 122 No known interaction 2,708 (incl. Methylnaltrexone)
Taking anything else?

Check Another of Your Medications Against Gamma-linolenic Acid (gla)

Covers the 2,830 medications we’ve checked against Gamma-linolenic Acid (gla). Pick one to open its full report.

What to actually watch for

No Interaction Found — But Data Suggests Gamma-linolenic Acid (gla) and Methylnaltrexone 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.

  • Bloating or gas / Stomach upset / Diarrhea / Vomiting / Nausea Additional detail

    Gamma-linolenic Acid (gla)

    “Orally, GLA may cause mild gastrointestinal effects such as dyspepsia, nausea, bloating, vomiting, soft stools, diarrhea, flatulence, and belching.”

    Gamma-linolenic Acid (gla) · Natural Medicines adverse-effect record, reported in diarrhea.

    4 sources cited
    1. 7701. Leventhal LJ, Boyce EG, Zurier RB. Treatment of rheumatoid arthritis with gammalinolenic acid. Ann Intern Med 1993;119:867-73. PubMed
    2. 7702. Zurier RB, Rossetti RG, Jacobson EW, et al. Gamma-linolenic acid treatment of rheumatoid arthritis. A randomized, placebo-controlled trial. Arthritis Rheum 1996;39:1808-17. PubMed
    3. 8926. Keen H, Payan J, Allawi J, et al. Treatment of diabetic neuropathy with gamma-linolenic acid. The gamma-Linolenic Acid Multicenter Trial Group. Diabetes Care 1993;16:8-15.
    4. 107927. Kim JH, Oh YW, Kim DH, Seo BH, Suh HS, Choi YS. A randomized, placebo-controlled trial of gamma linolenic acid as an add-on therapy to minocycline for the treatment of rosacea. Ann Dermatol 2020;32(6):466-72. PubMed

    Methylnaltrexone

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

Reported for Gamma-linolenic Acid (gla) but not commonly for Methylnaltrexone: bleeding or bruising.

Effects for Methylnaltrexone come from the ADVERSE REACTIONS section of its FDA label; effects for Gamma-linolenic Acid (gla) come from the Natural Medicines adverse-effect record, quoted above. Wording is matched across sources by our own clinical vocabulary, so treat this as a prompt to pay attention, not a diagnosis.

How to take them

Some Methylnaltrexone Products Have a Food Rule — Gamma-linolenic Acid (gla) Should Not Break It

At least one FDA label for a product containing Methylnaltrexone says to take it on an empty stomach. Most supplements — Gamma-linolenic Acid (gla) included — are taken with a meal, so the easy mistake is swallowing both together at breakfast. Where that rule applies, keep Methylnaltrexone on its own and move Gamma-linolenic Acid (gla) to a meal later in the day.

This may not be true of your version. Food instructions belong to the product, not the ingredient: two Methylnaltrexone products can carry different directions, and extended-release forms often differ from immediate-release ones. The label we read is quoted below — check the directions on your own box or bottle, or ask your pharmacist, for how to take the exact product you were given.

o In patients with chronic non-cancer pain and OIC, take RELISTOR tablets with water on an empty stomach at least 30 minutes before the first meal of the day.

From the Dosage and Administration section of the FDA label we read for Methylnaltrexone — where that label names a specific product, the instruction is that product's. Read the label on DailyMed ›

A food rule is not an interaction — it is about how much of the medicine you absorb. The directions that came with your own product, and your pharmacist, outrank anything on this page.

Everything else you take

See Every Supplement That Interacts With Methylnaltrexone

This page covers Gamma-linolenic Acid (gla) only. If you take other supplements — a multivitamin, a sleep aid, something for joints — the Methylnaltrexone page lists 3 supplements it has a documented interaction with, worst first, each one explained.

The most serious there right now: Fever Bark (moderate), Iboga (moderate) and Yohimbe (moderate).

By severity: 3 moderate.

From our pharmacist’s overview on the Methylnaltrexone page

“If you take methylnaltrexone (Relistor) for opioid-induced constipation, the supplement list to know is short: three ingredients, all rated moderate, none major. Yohimbe, fever bark, and iboga are all cleared by the same liver enzyme, CYP2D6, and methylnaltrexone can slow that enzyme, letting their active compounds build up in your blood.”

Reviewed by 2 · Jul 18, 2026

Open the Methylnaltrexone interaction page

How much people look this up

Where Gamma-linolenic Acid (gla) and Methylnaltrexone 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 Gamma-linolenic Acid (gla)
Steady interest

#1,344 of 1,452 supplements looked up here in the last 7 days

29 days ago today
Medication Methylnaltrexone
Steady interest

#2,330 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 Gamma-linolenic Acid (gla) reference on this page ↓
  • Freshness: we automatically re-check this combination every week — this pair was last verified September 13, 2026. The Gamma-linolenic Acid (gla) and Methylnaltrexone 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 Gamma-linolenic Acid (gla)

What is Gamma-linolenic Acid (gla)?

  • Eczema and dry skin
  • Rheumatoid arthritis
  • Diabetic nerve pain
  • PMS and breast pain
  • Menopausal symptoms

Gamma-linolenic acid (GLA) is an omega-6 fatty acid found in oils like evening primrose and borage. It is most studied for skin conditions, joint pain, and nerve pain, but the evidence is mixed and far from conclusive. It is generally well tolerated, but talk with your pharmacist or doctor before starting, especially if you are pregnant, breastfeeding, or take other medicines.

Seed oil (from evening primrose, borage, or black currant seeds) · Capsules, softgels, and oils (evening primrose oil, borage oil, black currant seed oil)

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

Gamma-linolenic Acid (gla): dosing

There is no single official or standardized dose of GLA. The amount of GLA varies depending on the source oil, since evening primrose, borage, and black currant seed oils contain different concentrations.Because products differ so much, the best approach is to follow the directions on the product label and choose a reputable brand. A pharmacist can help you compare products and figure out an appropriate amount for your situation.Do not assume more is better.

From our Gamma-linolenic Acid (gla) monograph — the full record covers uses, side effects and every documented interaction.

Read the full Gamma-linolenic Acid (gla) monograph & all interactions
Medication

About Methylnaltrexone

What Is Methylnaltrexone Used For?

Brand name: Relistor

Methylnaltrexone, sold as Relistor, treats opioid-induced constipation (OIC) — constipation caused by opioid pain medications. Both Relistor tablets and Relistor injection are approved for adults with chronic non-cancer pain, including those with pain related to a prior cancer or its treatment who do not need frequent opioid dose increases.

Relistor injection is also approved for adults with advanced illness or active cancer pain who require increasing opioid doses as part of palliative care.

See full Methylnaltrexone drug information
Keep checking

Other Drugs & Gamma-linolenic Acid (gla)

Browse every other medication we’ve checked against Gamma-linolenic Acid (gla) — both the ones with a known interaction and the ones without. Select any drug for the full detail.

0Major
122Moderate
0Minor
2,707No known interaction
122 Moderate 2,707 No interaction
Moderate

122 interactions

Showing 60 of 122 moderate interactions — see all 122 on the Gamma-linolenic Acid (gla) page.

No interaction 2,707 drugs checked — show the list

We also checked Gamma-linolenic Acid (gla) against these medications and found no known interaction in our sources. Open any page to confirm.

Showing the 60 most looked-up of 2,707 medications checked with no known interaction — see the full Gamma-linolenic Acid (gla) list.

See the full Gamma-linolenic Acid (gla) interactions page
See every supplement checked against Methylnaltrexone, ranked by severity
Evidence & sources

Gamma-linolenic Acid (gla) References

The 5 references that drive our Gamma-linolenic Acid (gla) 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. Guivernau M, Meza N, Barja P, Roman O. Clinical and experimental study on the long-term effect of dietary gamma-linolenic acid on plasma lipids, platelet aggregation, thromboxane formation, and prostacyclin production. Prostaglandins Leukot Essent Fatty A PubMed
  2. Leventhal LJ, Boyce EG, Zurier RB. Treatment of rheumatoid arthritis with gammalinolenic acid. Ann Intern Med 1993;119:867-73. PubMed
  3. Zurier RB, Rossetti RG, Jacobson EW, et al. Gamma-linolenic acid treatment of rheumatoid arthritis. A randomized, placebo-controlled trial. Arthritis Rheum 1996;39:1808-17. PubMed
  4. Keen H, Payan J, Allawi J, et al. Treatment of diabetic neuropathy with gamma-linolenic acid. The gamma-Linolenic Acid Multicenter Trial Group. Diabetes Care 1993;16:8-15.
  5. Kim JH, Oh YW, Kim DH, Seo BH, Suh HS, Choi YS. A randomized, placebo-controlled trial of gamma linolenic acid as an add-on therapy to minocycline for the treatment of rosacea. Ann Dermatol 2020;32(6):466-72. 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 Gamma-linolenic Acid (gla) and Methylnaltrexone Together: Common Questions

Is it safe to take Gamma-linolenic Acid (gla) with Methylnaltrexone?
We do not list a known interaction between Gamma-linolenic Acid (gla) and Methylnaltrexone. 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 Gamma-linolenic Acid (gla) and Methylnaltrexone have any of the same side effects?
Yes — our sources link each of them separately to 5 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.
Should I take Gamma-linolenic Acid (gla) and Methylnaltrexone at the same time of day?
At least one FDA label for a product containing Methylnaltrexone says to take it on an empty stomach, and supplements are usually taken with a meal — so taking them together at breakfast is the easy mistake. Where that applies, keep Methylnaltrexone on its own and move Gamma-linolenic Acid (gla) to a meal later in the day. Food instructions belong to the product rather than the ingredient, so check the directions on your own box. This is about absorption, not an interaction.
How was the Gamma-linolenic Acid (gla) and Methylnaltrexone combination checked?
Interactions in our licensed database are recorded against drug classes. Methylnaltrexone is filed under 1 classification, and Gamma-linolenic Acid (gla) has documented interactions with 1 drug class — none of Methylnaltrexone'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 Gamma-linolenic Acid (gla) interact with any other medications?
Yes. Gamma-linolenic Acid (gla) has 122 documented drug interactions in our database — Methylnaltrexone 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 Methylnaltrexone interact with any supplements?
Yes. Methylnaltrexone has documented interactions with 3 supplements in our database — Gamma-linolenic Acid (gla) is not one of them. The Methylnaltrexone 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

Gamma-linolenic Acid (gla) monograph Uses, safety profile, and every drug interaction in one place Methylnaltrexone drug information The full plain-English guide to this medication Methylnaltrexone supplement interactions Every supplement checked against Methylnaltrexone, 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 5 citations behind this page Ask a pharmacist Free, personal answer from our licensed team

Still Have a Question About Methylnaltrexone and Gamma-linolenic Acid (gla)?

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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.