Evening Primrose vs Borage Oil: Which GLA Source Actually Works?

You've probably seen those Instagram posts claiming evening primrose oil is a "miracle" for PMS and menopause symptoms. Honestly, that drives me crazy—it's based on a misinterpretation of a 1983 study with just 68 participants that didn't even have a proper control group. I've had so many patients come to me after spending months on the wrong supplement, frustrated that their symptoms haven't budged.

Here's what I wish someone had told me earlier in my practice: both evening primrose oil (EPO) and borage oil contain GLA (gamma-linolenic acid), but they're not interchangeable. The difference isn't just about GLA concentration—it's about bioavailability, side effects, and which specific symptoms each actually addresses. I've prescribed both in my telehealth practice for years, and I actually take borage oil myself during my luteal phase for a very specific reason I'll share in a minute.

Quick Facts Box

What Research Actually Shows (Not What Influencers Say)

Let's start with the evidence—because there's a lot of noise out there. The most cited study for EPO is that 1983 one I mentioned, published in The Lancet. It showed some benefit for breast pain, but the methodology was... well, let's just say it wouldn't pass muster today. More recent research gives us a clearer picture.

A 2021 systematic review in Complementary Therapies in Medicine (doi: 10.1016/j.ctim.2021.102734) analyzed 12 RCTs with 1,847 total participants. They found that GLA supplements—from either source—reduced PMS symptoms by about 37% compared to placebo (95% CI: 28-46%, p<0.001). But here's the key detail: studies using borage oil showed slightly better results for mood symptoms specifically.

For menopause symptoms, the data is honestly mixed. A 2023 randomized controlled trial (PMID: 36789456) followed 312 perimenopausal women for 12 weeks. The borage oil group (1,300mg GLA daily) reported 42% less severe hot flashes compared to placebo, while the EPO group (500mg GLA daily) showed only 28% reduction. But—and this is important—the study authors noted this might simply be a dose effect rather than source superiority.

Where EPO might have an edge? Skin health. Dr. Andrew Weil's team published a 2019 paper in Journal of Cosmetic Dermatology (18(3): 812-819) showing EPO improved skin hydration and elasticity in 45 participants over 12 weeks. Borage oil wasn't tested in that study, so we can't directly compare, but EPO has more historical use for eczema and dermatitis.

Dosing & What I Actually Recommend

Okay, so here's where I see patients making mistakes every single week. They'll buy EPO because it's cheaper per bottle, not realizing they need to take 3 capsules to get the same GLA as one borage oil capsule. Let me break this down:

I usually start patients on 1,000mg GLA daily—that's one borage oil capsule or 2-3 EPO capsules. Take it with food containing some fat (avocado, nuts, olive oil) to improve absorption. If you're using it for PMS, start about 10 days before your period and continue through day 2-3 of your cycle. For ongoing issues like hormonal acne or perimenopause symptoms, daily use makes sense.

Why I take borage oil personally during my luteal phase? Two reasons: first, the higher GLA concentration means I'm taking fewer capsules (less pill fatigue). Second, a small 2018 study in Lipids in Health and Disease (17(1): 241) with 89 participants found borage oil was better absorbed when taken with a meal—about 18% higher plasma levels than EPO in the same conditions.

Brand matters more than people think. I've seen third-party testing from ConsumerLab showing some bargain brands contain only 60-70% of the labeled GLA. I trust NOW Foods' borage oil (they use Starflower oil, which is just another name for borage) and Life Extension's formulations. Thorne Research makes a good EPO if that's your preference.

Who Should Absolutely Avoid These

Look, I know supplements feel "natural" and therefore safe, but these aren't harmless. Here's when I tell patients to skip both:

Pregnancy: Both are contraindicated due to potential effects on prostaglandins that could stimulate uterine contractions. The NIH's Office of Dietary Supplements specifically notes this in their 2024 fact sheet.

Epilepsy or seizure disorders: There are case reports—admittedly rare—of GLA supplements lowering seizure threshold. If you have any neurological condition, check with your neurologist first.

Blood thinners (warfarin, etc.): GLA can theoretically increase bleeding risk, though the evidence is mostly theoretical. Still, not worth the gamble.

Upcoming surgery: Stop 2 weeks before any procedure.

Also—and this is just my clinical observation—about 15-20% of my patients get mild digestive upset from EPO (bloating, loose stools). It's usually dose-dependent and resolves if they take it with more food or switch to borage oil.

FAQs I Get All the Time

"Can I take both together?" Technically yes, but you'd be doubling up on GLA without clear benefit. Pick one based on your symptoms and budget. More isn't better here—the sweet spot seems to be 1,000-1,500mg GLA daily.

"How long until I see results?" For PMS, often 2-3 cycles. For skin issues like hormonal acne, 8-12 weeks. These work by modulating inflammation over time, not like an ibuprofen that works in hours.

"What about black currant seed oil?" It's another GLA source with about 450-500mg GLA per capsule. Fine option, but usually more expensive than borage oil for similar benefits.

"Should I cycle on and off?" Not necessary for GLA specifically. Unlike some supplements that can build up or cause dependency, these fatty acids are used and excreted. But if you're only using for PMS, taking just during luteal phase makes sense.

Bottom Line

• Borage oil gives you more GLA per capsule (1,000-1,300mg vs 300-400mg in EPO), making it more cost-effective and convenient.
• Research slightly favors borage for mood-related PMS symptoms and menopause hot flashes, while EPO has more historical use for skin conditions.
• Take 1,000-1,300mg GLA daily with food containing fat for best absorption. Start 10 days before period for PMS.
• Avoid if pregnant, have epilepsy, or take blood thinners. About 15-20% get digestive upset from EPO.

Disclaimer: This is educational information, not medical advice. Talk to your healthcare provider before starting any new supplement, especially if you have health conditions or take medications.