Drug & supplement interaction

Gamma-linolenic Acid (gla) + Isoniazid

Isoniazid brand names: Laniazid, INH, Nydrazid.

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 Isoniazid 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

Gamma-linolenic Acid (gla) and Isoniazid

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 Isoniazid 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 Isoniazid and Gamma-linolenic Acid (gla)? Ask Dr. Brian Staiger, PharmD, BCPS directly ›
How we checked

Why No Interaction Is Listed for Isoniazid

Interactions in our licensed database are recorded against drug classes, not just single drug names. Isoniazid is filed under 8 classifications — including cytochrome p450 2c19 (cyp2c19) inhibitors, cytochrome p450 2c9 (cyp2c9) inhibitors, cytochrome p450 1a2 (cyp1a2) inhibitors. Gamma-linolenic Acid (gla) has documented interactions with 1 drug class — the most serious being anticoagulant/antiplatelet drugs (moderate) — and none of Isoniazid’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 — Isoniazid 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. Isoniazid)
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 Isoniazid 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.

  • Vomiting / Nausea reported in 5.6% of FDA reports for Isoniazid 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

    Isoniazid

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

Reported for Gamma-linolenic Acid (gla) but not commonly for Isoniazid: diarrhea, bloating or gas, stomach upset and bleeding or bruising.

Effects for Isoniazid 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. Where a percentage is shown, it is the share of 16,103 voluntary FDA FAERS reports for Isoniazid 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.

From our Q&A

Questions About Gamma-linolenic Acid (gla) or Isoniazid

These are real questions from readers, answered by the pharmacists at HelloPharmacist — written by a person, not generated from a database. Each one covers Gamma-linolenic Acid (gla) or Isoniazid, not necessarily both, but if one is close to what you were about to ask it will usually go further than a database entry can:

Not quite your question? Ask our pharmacists directly — it is free, there is no account required, and answers usually come back within 24 hours.

Everything else you take

See Every Supplement That Interacts With Isoniazid

This page covers Gamma-linolenic Acid (gla) only. If you take other supplements — a multivitamin, a sleep aid, something for joints — the Isoniazid page lists 84 supplements it has a documented interaction with, worst first, each one explained.

The most serious there right now: Activated Charcoal (major), Beer (major), Siberian Cocklebur (major), Wine (major) and Adrafinil (moderate).

By severity: 4 major · 67 moderate · 13 minor.

From our pharmacist’s overview on the Isoniazid page

“The liver does most of the worrying here. Isoniazid, a backbone of tuberculosis treatment, is already hard on the liver by itself, and 38 of the supplements on this list can add strain, from Siberian cocklebur, a major-rated entry, to everyday herbs like ashwagandha and black cohosh.”

Reviewed by 2 · Jul 18, 2026

Open the Isoniazid interaction page

How much people look this up

Where Gamma-linolenic Acid (gla) and Isoniazid 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

#1,336 of 1,452 supplements looked up here in the last 7 days

29 days ago today
Medication Isoniazid
Steady interest

#1,961 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 Isoniazid 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 Isoniazid

What Is Isoniazid Used For?

Brand names: Laniazid, INH, Nydrazid

Isoniazid is used to treat all forms of tuberculosis (TB) caused by susceptible bacteria. Because TB bacteria can quickly become resistant to a single drug, isoniazid must always be combined with other anti-TB medications when treating active TB — it is never used alone for active disease.

Isoniazid is also used as preventive therapy (sometimes called latent TB treatment) for people who have a positive TB skin test but do not yet have active disease. This includes people with HIV infection, close contacts of someone with active TB, recent TB skin test converters, and people with certain medical conditions — such as silicosis, diabetes mellitus, end-stage renal disease, leukemia, or Hodgkin's disease — that raise their TB risk.

Most-Reported Side Effects for Isoniazid

From FAERS, the FDA’s public side-effect reporting system (16,103 reports, all brands). Reports are voluntary and are not proof the drug caused the effect.

Fever 1,102 reports
Nausea 903 reports
Drug-induced liver injury 862 reports
Drug reaction with eosinophilia and systemic symptoms 744 reports
Vomiting 637 reports
See full Isoniazid 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 Isoniazid, 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 Isoniazid Together: Common Questions

Is it safe to take Gamma-linolenic Acid (gla) with Isoniazid?
We do not list a known interaction between Gamma-linolenic Acid (gla) and Isoniazid. 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 Isoniazid have any of the same side effects?
Yes — our sources link each of them separately to 2 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.
How was the Gamma-linolenic Acid (gla) and Isoniazid combination checked?
Interactions in our licensed database are recorded against drug classes. Isoniazid is filed under 8 classifications, and Gamma-linolenic Acid (gla) has documented interactions with 1 drug class — none of Isoniazid'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 — Isoniazid 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 Isoniazid interact with any supplements?
Yes. Isoniazid has documented interactions with 84 supplements in our database — Gamma-linolenic Acid (gla) is not one of them. The Isoniazid 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 Isoniazid drug information The full plain-English guide to this medication Isoniazid supplement interactions Every supplement checked against Isoniazid, 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 Isoniazid 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.