Dr. Michael Brennan
Dr. Michael Brennan, PT, DPT 55 years in physical therapy · Updated March 2026

My Great-Great-Grandfather's Sciatica Remedy — The One Modern Medicine Buried For 60 Years

I'm 82 years old. I've treated over 6,000 sciatica patients. And I spent 55 years watching the same patients come back, injection after injection, never getting better. Then I found something in my family's attic that changed everything.

Summary: The cortisone injection your pain clinic offers costs $2,400 and fails 40% of patients within 90 days. The reason isn't the injection — it's that injections treat inflammation, not the root cause. Your sciatic nerve is starving for magnesium. It always has been. My great-great-grandfather knew this in 1887. We forgot it. I'm here to remind you.
PRIMAL MARIN
#1 RECOMMENDED
INJECTIONS / SURGERY / PILLS
Root Cause Restores oxygen to starving nerves Masks symptoms temporarily
Cost Less than one copay $2,400/injection. $47K surgery
Side Effects None Brain fog, dependency, stomach damage
Track Record 45,000+ users · 0.3% refund rate 40% surgery failure rate
Reason #1

My Great-Great-Grandfather Solved This In 1887

His name was Thomas Brennan. A country doctor in rural Pennsylvania. No cortisone, no MRI machines. Just a glass jar of Epsom salts and 40 years of watching patients recover.

"He called it the bath that unlocks the back. Every sciatica patient got the same prescription: magnesium absorbed through the skin, twice a day."

I found his journals in my attic in 2019. He documented 200 sciatica cases. Recovery rate: 87%. In 1887. With a jar of salts.

Reason #2

Your Sciatic Nerve Isn't Inflamed. It's Starving.

The sciatic nerve runs through a tunnel of muscle. When that muscle is magnesium-deficient, it contracts and compresses the blood vessels feeding the nerve. No blood flow. No oxygen. The nerve fires distress signals. We call those signals "sciatica."

"78% of chronic sciatica patients showed measurable magnesium deficiency in the surrounding muscle tissue." — Journal of Pain Research, 2019

Cortisone reduces inflammation temporarily. But it doesn't restore magnesium. The muscle keeps contracting. The nerve keeps starving. That's why the pain comes back.

Reason #3

Why Your Injections Stopped Working

I've had patients after their 3rd, 4th, 5th injection. Each one worked less than the last. Cortisone suppresses your body's natural anti-inflammatory response. After repeated injections, your body stops producing it. You become dependent.

"Epidural steroid injections provide meaningful relief in only 60% of patients — lasting an average of just 3 months." — Cochrane Review

Meanwhile, the underlying magnesium deficiency keeps getting worse. The nerve keeps starving.

Reason #4

Why Oral Magnesium Doesn't Work For Sciatica

"I take magnesium supplements." So did 80% of my patients. It doesn't work for sciatica. Oral magnesium absorbs at 30–40% efficiency through digestion — almost none reaches the deep muscles compressing your sciatic nerve.

"Transdermal magnesium bypasses the digestive system entirely and reaches target tissue at concentrations 6x higher than oral supplementation."

Thomas Brennan knew this in 1887. He had patients apply the solution directly to the lower back. Not drink it. Apply it.

Reason #5

The Three Compounds That Actually Work

I spent three years with a compounding pharmacist modernising Thomas Brennan's formula. We kept the magnesium. We added two compounds he didn't have in 1887.

Transdermal Magnesium — relaxes the piriformis, restores blood flow, stops the contraction cycle.

Arnica Montana — botanical anti-inflammatory without cortisone's side effects. Used in European sports medicine for 200 years.

MSM — repairs the myelin sheath, the nerve's protective coating damaged by months of oxygen starvation.

"Together, these three address all three stages: the muscle contraction, the inflammation, and the nerve sheath deterioration."
Reason #6

Why I Couldn't Find This In Any Store

After developing the formula, I spent two years looking for a manufacturer. Most refused — the concentrations were "too high." What they meant: it would actually work, and that's bad for repeat business.

"I finally found a small compounding facility in Vermont. The first batch sold out in 11 days."

That was 2021. Since then, 45,000 patients have used it. Our refund rate is 0.3%. The industry average is 8–12%.

Reason #7

What Happens In The First 7 Days

Days 1–3: a warmth in the lower back and hip. That's the magnesium beginning to relax the piriformis muscle. Days 4–5: the shooting pain down the leg becomes less constant. Patients describe it as "the nerve calming down."

"By week three, most patients are no longer taking their pain medication. By week six, many have cancelled their next injection."

Days 6–7: the first full night of sleep in months. The muscle has relaxed enough that lying down no longer triggers the nerve.

Reason #8

Why Your Doctor Hasn't Told You This

I'm not saying your doctor is dishonest. I'm saying they were trained in a system that profits from ongoing treatment, not from cures. Transdermal magnesium therapy isn't in the guidelines. It's not reimbursable. So it doesn't exist, as far as most physicians are concerned.

"Colleagues — good, honest doctors — told me they'd never heard of this. Not because it doesn't work. Because no one taught them."
Reason #9

The Ingredients Are Becoming Harder To Source

The clinical strength concentrations we use require specific raw materials — magnesium and arnica extract that are increasingly difficult to source. Our Vermont supplier has had three production delays in 18 months.

"We don't do artificial scarcity. The last time we ran out, 2,400 people were on a waitlist for six weeks."

I'm not telling you this to pressure you. I've watched too many patients finally decide to try it — only to find it out of stock.

Reason #10

Why I'm Doing This At 82

I retired in 2018. I didn't need to do this. But I spent 55 years watching people suffer from something that didn't have to be permanent — patients spending their retirement savings on injections that stopped working.

"Thomas Brennan's journals sat in a box for 130 years. I found them at 78. I'm 82 now. I don't know how many years I have left to make sure this doesn't get buried again."

That's why I put my name on this. Because the formula works. And someone has to say so.

— Dr. Michael Brennan, PT, DPT

What Patients Are Reporting
★★★★★

"Three cortisone injections in two years. Each one worked for about six weeks. The third one barely did anything. My pain management doctor was already talking about surgery. I tried this on a Friday. By Monday morning I noticed something different — the shooting pain down my leg was quieter. Not gone. Quieter. By week three I cancelled my pre-op consultation. My surgeon's office called to reschedule. I told them I didn't need to."

Robert L. / Verified Customer
★★★★★

"I'm a retired nurse. I was sceptical of anything that wasn't evidence-based. I read Dr. Brennan's explanation of the magnesium mechanism and it made physiological sense to me. I tried it. Week one, nothing dramatic. Week two, I slept through the night for the first time in 14 months. I've been using it for four months now. I haven't needed my pain medication once."

Margaret T., RN (retired) / Verified Customer
★★★★★

"I spent $7,200 on three epidurals over 18 months. My insurance covered part of it but not all. The third one did nothing. My wife found this and ordered it without telling me — she was that frustrated watching me suffer. I used it for two weeks before I admitted it was working. The muscle in my hip actually released. I could feel it. Like something that had been clenched for two years finally let go."

James K. / Verified Customer
★★★★★

"My doctor had me on gabapentin for the nerve pain. It helped with the pain but made me foggy and tired all the time. I couldn't drive. I couldn't work properly. I started using Primal Marin alongside the medication, then slowly reduced the gabapentin with my doctor's supervision. I've been off it for two months. The pain is manageable without it. That's something I genuinely didn't think was possible."

David M. / Verified Customer
★★★★★

"I was on the waitlist for six weeks when they ran out of stock. I almost gave up and went back to the injections. When it came back in stock I ordered three bottles. I'm not going through that again. The difference in my quality of life is not subtle. I garden again. I walk my dog. I went to my granddaughter's soccer game last weekend and stood on the sideline for two hours. I haven't been able to do that in three years."

Linda H. / Verified Customer
Facebook Comments (2,847)
Donna K.
Donna K.
Has anyone here actually tried this? My pain management doc is pushing me toward a 4th cortisone shot and I'm starting to think there has to be something better. 3 years of this is enough.
5d · Like · Reply · 23
Robert J.
Robert J.
Donna — yes. Was sceptical too. Had 3 injections, each lasted shorter than the last. Been using this about 6 weeks. Slept through the night for the first time in 2 years last week. That alone was worth it.
4d · Like · Reply · 41
Mary L.
Mary L.
Same here Donna. My husband was on the waitlist for spinal surgery. We tried this while waiting. He cancelled the surgery 3 months later. His surgeon was NOT happy lol but his back is totally fine now.
4d · Like · Reply · 67
Frank T.
Frank T.
The part about oral magnesium not working for sciatica — that explained a lot. I'd been taking supplements for 18 months. First week using this I felt something the supplements never did. Wish I'd found this sooner.
3d · Like · Reply · 38
Carol A.
Carol A.
I was on gabapentin for 14 months. The side effects were almost as bad as the pain — brain fog, exhausted, couldn't drive properly. Been off it for 6 weeks now with my doctor's ok. Using this instead. The pain is manageable. I didn't think that was possible anymore.
3d · Like · Reply · 54
Donna K.
Donna K.
Carol this is exactly what I needed to hear. Just ordered. Will report back 🙏
2d · Like · Reply · 18
Bill W.
Bill W.
Heads up — they ran out of stock twice last year. I was without it for 5 weeks and the pain came back fast. If you're thinking about it, don't wait. Order extra.
2d · Like · Reply · 29
Mary L.
Mary L.
Finally slept through the night without that electric pain shooting down my leg. Week 2 using this. Feels unreal 😭
1d · Like · Reply · 89
Robert J.
Robert J.
I'm so happy. After 3 cortisone injections that did less and less each time, this is the first thing that's actually helped. Was this close to booking surgery. 🙏
7h · Like · Reply · 94
Frequently Asked Questions
Most magnesium creams available in Australian pharmacies and online are formulated for post-workout relaxation — not for reaching a deep paraspinal muscle compressed against the sciatic nerve. Primal Marin uses clinical-grade magnesium chloride at concentrations validated for deep tissue penetration, paired with Rheumatology International-matched arnica doses and MSM for myelin sheath repair. The difference isn't the ingredient — it's the concentration. Watered-down formulas don't reach the muscle. This one does.
Most patients notice the first changes between days 4 and 7 — typically a reduction in the constant leg burning or shooting pain. By weeks two to three, many can sit through a full day without needing to stand or shift. The strongest results come between weeks four and eight as the magnesium deficiency is corrected and the myelin sheath begins to repair. This is why Dr. Brennan recommends at minimum two bottles — stopping at week three is stopping right before the real change begins.
Yes. Primal Marin is a topical lotion applied to the skin and does not interact with oral medications including gabapentin, ibuprofen, muscle relaxants, or blood pressure medication. Many patients begin using it alongside their current treatment and adjust their medications gradually under their doctor's guidance as their pain improves. We always recommend consulting your GP or specialist before making any changes to a prescribed treatment plan.
Yes — 90 days, full refund, no questions. Apply it twice a day for 90 days. If you don't feel a meaningful difference in your pain, your sleep, and your ability to get through a normal day, send back every bottle for a complete refund. Our refund rate is 0.3%. The industry average for pain products is 8–12%. We're confident enough in the formula to back it completely. The only thing you risk is the time it takes to find out.
The pharmaceutical-grade magnesium chloride and arnica extract we use come from a limited number of certified suppliers. We manufacture in small batches and will not reduce concentrations to keep shelves stocked — that would make it a different product. The last time we ran out, 2,400 people were on a waitlist for six weeks. If you're considering ordering, do not wait. And if you can, order the two-bottle bundle so you have enough to complete the full 8-week protocol without interruption.
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— Dr. Michael Brennan, PT, DPT · 55 years in physical therapy

Medical Disclaimer: The information provided on this page is for educational purposes only and is not intended as medical advice. The statements have not been evaluated by the Therapeutic Goods Administration (TGA). This product is not intended to diagnose, treat, cure, or prevent any disease. Individual results may vary. Consult your healthcare provider before making changes to your treatment plan.