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Dietary supplement

Mega-GLA 300 Ingredients & Drug Interactions

by Source Naturals

Mega-GLA 300 label
See full label image
Softgel Capsule Category: Fat/fatty Acid
Most serious interaction: Moderate
Clinical methodology reviewed by · Updated Sep 23, 2026 · Label data from the NIH DSLD
What is this page for?

First and foremost: checking Mega-GLA 300 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

Mega-GLA 300 is a dietary supplement by Source Naturals with 1 active ingredient. Its ingredients are commonly taken for eczema and dry skin, rheumatoid arthritis, inflammation.Based on those ingredients, 312 medications have a known interaction with it, the most serious rated moderate. The ingredients most likely to interact are Pure Borage Seed Oil. Use the checker below to test your specific medication, or read the full HelloPharmacist Interaction Report.

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Check Your Meds Against Mega-GLA 300 by Source Naturals

Ask about any prescription or over-the-counter medication and we check it for interactions with Mega-GLA 300 by Source Naturals — and tell you which ingredient is responsible.

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HelloPharmacist Scorecard of Mega-GLA 300 by Source Naturals

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 Jul 11, 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 4 of its 4 active ingredients.
  • “Pure Borage Seed Oil” is listed as a grouped ingredient — the label gives one combined amount (1.30 Gram(s)) without saying how much of each component you get.

Mega-GLA 300 has 4 active ingredients, all fatty acids from borage seed oil. Oleic acid, linoleic acid, gamma-linolenic acid (GLA), and palmitic acid are the working components.

The softgel is filled with gelatin, glycerin, and purified water — the inactive ingredients that hold everything together.

Does it work?

Couldn't assess
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
Not assessable

We hold no graded evidence for this product's ingredients for its stated purpose.

Why this rating?
  • The label markets this product for: Support healthy skin and joint function.
  • We looked for evidence on: Atopic dermatitis (eczema), Rheumatoid arthritis (RA), Neurodermatitis, Seborrheic dermatitis, Skin barrier health, Inflammatory response — and 1 related terms.
  • Our graded evidence for these ingredients doesn't cover that particular purpose.

Oleic acid in this product is rated possibly effective for high cholesterol (hypercholesterolemia) and coronary heart disease. That's the only ingredient we have effectiveness data for.

For the others — gamma-linolenic acid, linoleic acid, and palmitic acid — the evidence isn't established in our data.

The evidence, ingredient by ingredient Borage Oleic Acid

How safe is it?

Some data gaps
Safety Information · database check
Some gaps

Safety data exists for these ingredients, but with some important gaps.

Why this rating?
  • We hold adverse-effect (side-effect) data for 0 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.

Oleic acid from food sources like olive oil is generally well tolerated and recognized as safe at normal amounts. At supplement-level doses, though, safety data in pregnancy and breastfeeding is limited.

The product hasn't been well studied at concentrated doses in these groups, so talk with your pharmacist or doctor if you're pregnant, nursing, or planning to be.

Side effects, ingredient by ingredient Borage Oleic Acid

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 — Oleic Acid.
  • The most serious interaction on file is rated Moderate.
  • Some involve high-stakes drug classes: diabetes medications.
  • For scale: 86 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.

If you take antidiabetes drugs (medications that lower blood sugar), check with your pharmacist or doctor before taking Mega-GLA 300 — oleic acid may increase their effects and lower your blood sugar more than expected. No other medication interactions are documented for the ingredients we were able to check.

Check your own medication Run your meds through the checker above

The bottom line

Scorecard at a glanceFully disclosed formula with no assessable stated purpose. Moderate medication interactions have been identified, and some safety-information gaps remain.

This product may help with cholesterol and heart health if oleic acid's role is meaningful for you. If you take diabetes medication, that's the main flag — check with us before you start.

Anyone pregnant or breastfeeding should talk to their pharmacist first, since supplement doses haven't been well studied in those situations.

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

Assessment coverage: 1 of 4 active ingredients matched to our full ingredient reviews (monographs). Based on the product label dated Dec 13, 2022.

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 Mega-GLA 300, straight from the product label.

Brand Source Naturals
Barcode (UPC) 021078009108
Net contents 60 Softgel(s)
Market status On market
Date entered into DSLD Dec 13, 2022
DSLD ID 275047
Product type Fat/fatty Acid
Supplement form Softgel Capsule
Dietary claims / uses Nutrient, All Other, Structure/Function
Intended target group(s) Adult (18 - 50 Years), Gluten Free, 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 Mega-GLA 300 by Source Naturals, 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 Softgel(s)
Maximum serving Sizes:
1 Softgel(s)
Servings per container
60
UPC/BARCODE
021078009108
IngredientAmount% DV
Calories15 Calorie(s)--
Total Fat1 Gram(s)2%
Gamma-Linolenic Acid300 mg--
Linoleic Acid477 mg--
Oleic Acid194 mg--
Palmitic Acid112 mg--
Pure Borage Seed Oil1.3 Gram(s)--

Other ingredients: Gelatin, Glycerin, Water, Purified

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.
FDA Statement of Identity

Dietary Supplement

Formula

Borage seed oil

GLA (gamma-linolenic acid) is an essential fatty acid and a precursor of key regulating hormones called PGE1 prostaglandins. Many dietary and lifestyle factors can seriously reduce the body's GLA production. Borage seed oil provides the highest yield of GLA in the botanical kingdom (more than twice the GLA yield of evening primrose oil). The borage seed oil is extracted by a special cold-press process, which leaves no harmful residues and is HEXANE-FREE.

Suggested/Recommended/Usage/Directions

Suggested Use: 1 softgel daily with a meal.

Precautions

NOTE: If you are pregnant or breastfeeding, consult your health care professional before using this product.

Do not use if tamper-evident seal is broken or missing.

Keep out of the reach of children.

Storage

Store in a cool, dry place.

Formulation

Contains no yeast, dairy, egg, gluten, corn, soy or wheat. Contains no sugar, starch, salt, preservatives or artificial color, flavor or fragrance.

Hexane free

FDA Disclaimer Statement

These statements have not been evaluated by the Food and Drug Administration. This product is not intended to diagnose, treat, cure or prevent any disease.

Brand IP Statement(s)

Copyright SOURCE NATURALS, INC.

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

See for yourself

Mega-GLA 300 by Source Naturals label

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

Mega-GLA 300 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 Mega-GLA 300 by Source Naturals

This is the 1 active ingredient this product is made of. Select it to open its full monograph.

Serving size1 Softgel(s) Dosage formSoftgel Capsule Servings per container60 Amounts shown are per serving.

Pure Borage Seed Oil

Interacts with
226 drugs
1.3 Gram(s) per serving

Borage is a Mediterranean herb whose seed oil is rich in gamma-linolenic acid (GLA), an omega-6 fatty acid studied mostly for skin conditions and arth...

Pure Borage Seed Oil monograph & interactions
  • › Gamma-Linolenic Acid
  • › Linoleic Acid
  • › Oleic Acid
  • › Palmitic Acid

Other (inactive) ingredients: Gelatin, Glycerin, Water, Purified. These complete the product’s ingredient list but are not active constituents.

Interaction report

Mega-GLA 300 by Source Naturals Drug Interactions

Want to check YOUR meds against Mega-GLA 300?

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
312Drugs
312 Moderate

Ingredients driving the most interactions

Pure Borage Seed Oil 226

Individual Drug Interactions

The ingredients in Mega-GLA 300 interact with 312 drugs. Click any drug to see the details.

1 of the 1 ingredient in Mega-GLA 300 interact with drugs. Each result below shows which ingredient is responsible. Pure Borage Seed Oil

Each ingredient & the kinds of drugs it affects

For each ingredient in Mega-GLA 300 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.

Pure Borage Seed Oil3 drug types · 226 drugs

Anticoagulant/Antiplatelet Drugs

Theoretically, borage seed oil may increase the risk of bleeding if used with anticoagulant or antiplatelet drugs.
In healthy individuals, borage seed oil supplementation does not seem to affect platelet aggregation. However, gamma-linolenic acid, a constituent of borage seed oil, seems to decrease platelet aggregation by 45% and increase the risk of bleeding by 40% in animal and clinical research.

Likelihood Possible Evidence B
Cytochrome P450 3A4 (Cyp3A4) Inducers

Theoretically, taking borage with drugs that induce CYP3A4 might increase levels of pyrrolizidine alkaloid (PA) toxic metabolites.
Although borage seed oil contains little to no PAs, some borage plant parts, such as the leaf, flower, and seed, can contain hepatotoxic PAs. Hepatotoxic PAs are substrates of CYP3A4, which converts these chemicals into toxic metabolites. Tell patients to avoid borage preparations that are not certified and labeled as hepatotoxic PA-free.

Likelihood Possible Evidence D
Phenothiazines

Theoretically, taking borage sed oil with phenothiazines might increase the risk of seizures.
Borage seed oil contains gamma-linolenic acid (GLA). There is concern that taking supplements containing GLA might cause seizures, or lower the seizure threshold, when taken with phenothiazines. This is based on limited data from two reports published in the 1980s. In one report, three patients with schizophrenia who had received phenothiazines developed EEG changes suggestive of temporal lobe epilepsy after starting treatment with evening primrose, another source of GLA. However, none experienced an actual seizure. In the other report, two patients with schizophrenia who were stabilized on phenothiazines developed seizures when evening primrose 4 grams daily was added. One of these patients had a prior history of seizures. It is unclear whether evening primrose had any additive epileptogenic effects with the phenothiazines, but there is no evidence that taking GLA-containing supplements alone can cause seizures.

Likelihood Possible Evidence D
Pure Borage Seed Oil full monograph & interactions
The maker

Brand information

Manufacturer and brand details for Mega-GLA 300, from the product label.

Source Naturals

Name
Source Naturals, Inc.
Street Address
P. O. Box 2118
City
Santa Cruz
State
CA
ZipCode
95062
Web Address
www.sourcenaturals.com
Pharmacist Counseling Corner

Mega-GLA 300 by Source Naturals: Common Questions

Does Mega-GLA 300 by Source Naturals interact with any medications?
Yes. Based on its ingredients, Mega-GLA 300 has a known interaction with 312 medications. Use the checker to see how it interacts with a specific drug.
How can one product interact with so many drugs?
Mega-GLA 300 contains a single active ingredient, and that one ingredient can interact with many different medications on its own. We check it against each medication and show the mechanism 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.
Will this help my cholesterol?
Oleic acid in this product is rated possibly effective for high cholesterol and coronary heart disease. That means there's some evidence, but it's not definitive. Your results will depend on your diet, genetics, and overall health — talk to your doctor about whether this fits your plan.
Can I take this if I'm pregnant?
There isn't enough safety data on Mega-GLA 300 at supplement doses during pregnancy. Food amounts of oleic acid are fine, but concentrated supplements haven't been well studied. Talk with your pharmacist or doctor before starting it.
What's in this product?
Mega-GLA 300 is four fatty acids from borage seed oil: oleic acid, linoleic acid, gamma-linolenic acid, and palmitic acid. It's wrapped in a gelatin softgel with glycerin and water.
Is this safe to take every day?
Oleic acid from foods is well tolerated at normal amounts. We don't have long-term safety data on this supplement dose specifically, so if you plan to take it daily, ask your pharmacist whether it's right for you and your health.
What's GLA used for?
GLA — gamma-linolenic acid — is one of the fatty acids in this product. We don't have effectiveness ratings for it in our data, so I can't tell you what research shows it does.

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

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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.

Mega-GLA 300 label
Go deeper

The Full Monographs Behind Mega-GLA 300’s Ingredients

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

Herb & supplement monograph

Borage

Interacts with 226 drugs

Borage is a Mediterranean herb whose seed oil is rich in gamma-linolenic acid (GLA), an omega-6 fatty acid studied mostly for skin conditions and arthritis with mixed results. The plant's le...

Read the full Borage monograph → Herb & supplement monograph

Oleic Acid

Interacts with 86 drugs

Oleic acid is a heart-healthy monounsaturated fat found mainly in olive oil, canola oil, avocados, and nuts. As part of a Mediterranean-style diet, it is widely viewed as a healthier replace...

Read the full Oleic Acid monograph →
Sources

Sources & How We Checked

Mega-GLA 300'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 30 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.

Oleic Acid 19 references
  1. Madigan C, Ryan M, Owens D, et al. Dietary unsaturated fatty acids in type 2 diabetes: higher levels of postprandial lipoprotein on a linoleic acid-rich sunflower oil diet compared with an oleic acid-rich olive oil diet. Diabetes Care 2000;23:1472-7. PubMed
  2. Gillingham, L. G., Gustafson, J. A., Han, S. Y., Jassal, D. S., and Jones, P. J. High-oleic rapeseed (canola) and flaxseed oils modulate serum lipids and inflammatory biomarkers in hypercholesterolaemic subjects. Br J Nutr 2011;105(3):417-427. PubMed
  3. Jones PJ, Senanayake VK, Pu S, Jenkins DJ, Connelly PW, Lamarche B, Couture P, Charest A, Baril-Gravel L, West SG, Liu X, Fleming JA, McCrea CE, Kris-Etherton PM. DHA-enriched high-oleic acid canola oil improves lipid profile and lowers predicted cardiova
  4. Cater, N. B., Heller, H. J., and Denke, M. A. Comparison of the effects of medium-chain triacylglycerols, palm oil, and high oleic acid sunflower oil on plasma triacylglycerol fatty acids and lipid and lipoprotein concentrations in humans. Am.J Clin.Nutr PubMed
  5. Mozaffarian D, Clarke R. Quantitative effects on cardiovascular risk factors and coronary heart disease risk of replacing partially hydrogenated vegetable oils with other fats and oils. Eur J Clin Nutr. 2009;63(Suppl 2):S22-33. PubMed
  6. Cao Y, Hou L, Wang W. Dietary total fat and fatty acids intake, serum fatty acids and risk of breast cancer: A meta-analysis of prospective cohort studies. Int J Cancer. 2016;138(8):1894-904. doi: 10.1002/ijc.29938. PubMed
  7. FDA completes review of qualified health claim petition for oleic acid and the risk of coronary heart disease. November 2018. Available at: www.fda.gov/Food/NewsEvents/ConstituentUpdates/ucm624758.htm. Accessed January 25, 2019.
  8. Liu X, Kris-Etherton PM, West SG, et al. Effects of canola and high-oleic-acid canola oils on abdominal fat mass in individuals with central obesity. Obesity. 2016;24(11):2261-2268. PubMed
  9. Bowen KJ, Kris-Etherton PM, West SG, et al. Diets enriched with conventional or high-oleic acid canola oils lower atherogenic lipids and lipoproteins compared to a diet with a western fatty acid profile in adults with central adiposity. J Nutr. 2019;149(3 PubMed
  10. Steffen BT, Duprez D, Szklo M, Guan W, Tsai MY. Circulating oleic acid levels are related to greater risks of cardiovascular events and all-cause mortality: The Multi-Ethnic Study of Atherosclerosis. J Clin Lipidol. 2018;12(6):1404-1412. PubMed
  11. Banim PJ, Luben R, Khaw KT, Hart AR. Dietary oleic acid is inversely associated with pancreatic cancer - Data from food diaries in a cohort study. Pancreatology. 2018;18(6):655-660. PubMed
  12. Morin SJ, Gaziano JM, Djoussé L. Relation between plasma phospholipid oleic acid and risk of heart failure. Eur J Nutr. 2018;57(8):2937-2942. PubMed
  13. Samieri C, Féart C, Proust-Lima C, et al. Olive oil consumption, plasma oleic acid, and stroke incidence: the Three-City Study. Neurology. 2011;77(5):418-25. PubMed
  14. Compher CW, Kinosian BP, Rubesin SE, Ratcliffe SJ, Metz DC. Energy absorption is reduced with oleic acid supplements in human short bowel syndrome. JPEN J Parenter Enteral Nutr. 2009;33(1):102-8. PubMed
  15. Ben Fradj MK, Ouanes Y, Hadj-Taieb S, et al. Decreased oleic acid and marine n?-?3 polyunsaturated fatty acids in Tunisian patients with urothelial bladder cancer. Nutr Cancer. 2018;70(7):1043-1050.
  16. de Silva PS, Luben R, Shrestha SS, Khaw KT, Hart AR. Dietary arachidonic and oleic acid intake in ulcerative colitis etiology: a prospective cohort study using 7-day food diaries. Eur J Gastroenterol Hepatol. 2014;26(1):11-8. PubMed
  17. Higashi K, Shige H, Ito T, et al. Effect of a low-fat diet enriched with oleic acid on postprandial lipemia in patients with type 2 diabetes mellitus. Lipids. 2001;36(1):1-6. PubMed
  18. Lin HC, van Citters GW, Heimer F, Bonorris G. Slowing of gastrointestinal transit by oleic acid: a preliminary report of a novel, nutrient-based treatment in humans. Dig Dis Sci. 2001;46(2):223-9. PubMed
  19. Li D, Tong Y, Li Y. Associations between dietary oleic acid and linoleic acid and depressive symptoms in perimenopausal women: The Study of Women's Health Across the Nation. Nutrition. 2020 Mar;71:110602. PubMed

See these in context on the Oleic Acid monograph →

Borage 11 references
  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. WHO working group. Pyrrolizidine alkaloids. Environmental Health Criteria, 80. WHO: Geneva, 1988.
  3. Fan YY, Chapkin RS. Importance of dietary gamma-linolenic acid in human health and nutrition. J Nutr 1998;128:1411-4.
  4. Takwale A, Tan E, Agarwal S, et al. Efficacy and tolerability of borage oil in adults and children with atopic eczema: randomised, double blind, placebo controlled, parallel group trial. BMJ 2003;327:1385. PubMed
  5. Chojkier M. Hepatic sinusoidal-obstruction syndrome: toxicity of pyrrolizidine alkaloids. J Hepatol 2003;39:437-46. PubMed
  6. Roeder E. Medicinal plants in Europe containing pyrrolizidine alkaloids. Pharmazie 1995;50:83-98.
  7. Wang YP, Yan J, Fu PP, Chou MW. Human liver microsomal reduction of pyrrolizidine alkaloid N-oxides to form the corresponding carcinogenic parent alkaloid. Toxicol Lett 2005;155:411-20. PubMed
  8. Holman CP and Bell AF. A trial of evening primrose oil in the treatment of chronic schizophrenia. J Orhtomolecular Psych 1983;12:302-304.
  9. Vaddadi KS. The use of gamma-linolenic acid and linoleic acid to differentiate between temporal lobe epilepsy and schizophrenia. Prostaglandins Med 1981;6(4):375-379. PubMed
  10. Bard, J. M., Luc, G., Jude, B., Bordet, J. C., Lacroix, B., Bonte, J. P., Parra, H. J., and Duriez, P. A therapeutic dosage (3 g/day) of borage oil supplementation has no effect on platelet aggregation in healthy volunteers. Fundam.Clin.Pharmacol. 1997;1
  11. Puri BK. The safety of evening primrose oil in epilepsy. Prostaglandins Leukotrienes Essential Fatty Acids 2007;77:101-3. PubMed

See these in context on the Borage 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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