Comparison
Low-Dose Naltrexone vs Magnesium L-Threonate
Side-by-side of Low-Dose Naltrexone and Magnesium L-Threonate. Every row below is pulled from the compound schema and will update as our data grows. For deeper reads, follow through to each compound page.
Low-Dose Naltrexone
Low dose naltrexone at 1.5 to 4.5 mg, one-tenth the 50 mg addiction dose. Compounded Rx. Small trials in fibromyalgia, Crohn's, Hashimoto's.
Magnesium L-Threonate
Magnesium l-threonate (Magtein) crosses the blood-brain barrier. Typical dose 1,500-2,000 mg. Sleep and cognitive trial data, side effects.
Effects at a glance
Low-Dose Naltrexone
- •Off-label use at 1.5 to 4.5 mg, roughly one-tenth the FDA-approved 50 mg addiction-treatment dose
- •Proposed mechanisms include brief opioid receptor blockade triggering rebound endogenous opioid release, plus TLR4 antagonism
- •Compounded prescription only; insurance rarely covers; cash prices 20 to 80 USD per month
- •Younger 2013 reported ~30% pain reduction in fibromyalgia at 4.5 mg in a small crossover trial
- •Smith 2011 reported endoscopic improvement in active Crohn's disease (n=40 placebo-controlled)
- •Vivid dreams affect 20 to 40% in first 2 weeks; manageable by switching to morning dosing
Magnesium L-Threonate
- •Distinct magnesium salt designed for blood-brain barrier penetration; not a higher-quality systemic magnesium
- •Liu 2010 rodent study: elevated CSF magnesium ~15% and increased hippocampal synaptic density
- •Trial portfolio in humans is small and mostly Magtein-funded; cognitive effects are modest where reported
- •Typical dose 1500 to 2000 mg/day delivers only ~108 to 144 mg of elemental magnesium
- •GI tolerability comparable to other magnesium forms; loose stools in a minority at 2000 mg/day
- •Distinct from magnesium glycinate, which is the conventional sleep/anxiety/repletion form
Side-by-side
| Attribute | Low-Dose Naltrexone | Magnesium L-Threonate |
|---|---|---|
| Category | pharmaceutical | supplement |
| Also known as | LDN, naltrexone (low dose) | Mg-T, MgT, Magtein, magnesium threonate |
| Half-life (hr) ↗ | 4 | 4 |
| Typical dose (mg) ↗ | 4.5 | 2000 |
| Dosing frequency | once daily, typically at bedtime | 1 to 3 times daily |
| Routes | oral | oral |
| Onset (hr) | 1 | 1 |
| Peak (hr) | 1.5 | 2 |
| Molecular weight | 341.4 | 294.5 |
| Molecular formula | C20H23NO4 | C8H14MgO10 |
| Mechanism | Brief mu-opioid receptor antagonism proposed to trigger compensatory upregulation of endogenous opioids; secondary TLR4 antagonism on microglia and immune cells contributes to anti-inflammatory effect. | Proposed to deliver magnesium across the blood-brain barrier more effectively than other oral salts via threonate-related transporters, raising CNS magnesium and modulating NMDA receptor function and synaptic plasticity. |
| Legal status | Off-label compounded prescription (naltrexone is FDA approved for opioid and alcohol use disorder at 50 mg) | OTC dietary supplement |
| WADA status | allowed | allowed |
| DEA / Rx | Rx only (not a controlled substance) | OTC supplement (not scheduled) |
| Pregnancy | Insufficient data; not routinely recommended | Standard magnesium safety; Mg-T-specific data limited |
| CAS | 16590-41-3 | 778571-57-6 |
| PubChem CID | 5360515 | 10691810 |
| Wikidata | Q426444 | Q27151568 |
Safety profile
Low-Dose Naltrexone
Common side effects
- vivid dreams
- sleep disruption
- headache
- mild GI upset
- fatigue (early)
Contraindications
- concurrent opioid use
- acute hepatitis or liver failure
- opioid dependence
- pregnancy (insufficient data)
Interactions
- opioid analgesics (oxycodone, morphine, codeine): blocks analgesic effect; precipitates withdrawal in dependent users(major)
- tramadol: blocks opioid component of analgesia(major)
- thyroid hormone replacement: may alter dose requirements after immune modulation; monitor TSH(minor)
Magnesium L-Threonate
Common side effects
- loose stools
- mild GI upset
- headache (rare)
- fatigue (rare)
Contraindications
- severe renal impairment (eGFR below 30)
- hypermagnesemia
- myasthenia gravis (high doses)
- concurrent IV magnesium therapy
Interactions
- tetracyclines and fluoroquinolones: magnesium chelation reduces antibiotic absorption; separate by 2 to 4 hours(moderate)
- bisphosphonates: reduced absorption; separate by 2 hours minimum(moderate)
- muscle relaxants and aminoglycosides: potentiated neuromuscular blockade at high doses(moderate)
- antihypertensives: additive blood pressure reduction at high doses(minor)
Which Should You Take?
Magnesium L-Threonate comes out ahead for most readers on the criteria we weight: 2 catalogued goals, OTC dietary supplement, oral dosing, with a Tier-B outcome catalogued. Low-Dose Naltrexone is the right call when one of the conditionals below applies.
- → If your priority is immune support, pick Low-Dose Naltrexone.
- → If your priority is pain modulation, pick Low-Dose Naltrexone.
- → If your priority is focus or working memory, pick Magnesium L-Threonate.
- → If your priority is sleep onset or sleep quality, pick Magnesium L-Threonate.
Edge case: If you want to avoid prescription-only, Magnesium L-Threonate is the more accessible choice.
Default choice: Magnesium L-Threonate. Lower friction to source, and broader goal coverage. Reach for Low-Dose Naltrexone only if your priority sits squarely in the goals it owns above.
This verdict is generated from each compound's schema (goals, legal status, evidence outcomes, dosing route). It updates automatically as our compound data evolves; the deeper read sits on each individual compound page.
Common questions
What is the difference between Low-Dose Naltrexone and Magnesium L-Threonate?
Low-Dose Naltrexone and Magnesium L-Threonate differ in category (pharmaceutical vs supplement), mechanism, and typical dosing. See the side-by-side table for full details.
Which has a longer half-life, Low-Dose Naltrexone or Magnesium L-Threonate?
Low-Dose Naltrexone half-life is 4 hours; Magnesium L-Threonate half-life is 4 hours.
Can you stack Low-Dose Naltrexone with Magnesium L-Threonate?
Stack compatibility depends on mechanism overlap, legal status, and individual response. Check each compound page for specific interactions and contraindications before combining.
Go deeper