Comparison
Magnesium L-Threonate vs Semax
Side-by-side of Magnesium L-Threonate and Semax. 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.
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.
Semax
Semax peptide benefits: nootropic ACTH(4-10) analog without corticotropic activity. Cognitive enhancement, neuroprotection, intranasal dosing, Russian stroke.
Effects at a glance
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
Semax
- •Synthetic heptapeptide analog of ACTH(4-10) developed in Russia in the 1980s
- •Approved in Russia for ischemic stroke, cognitive impairment, and cerebrovascular disorders
- •Lacks the corticotropic activity of native ACTH due to the Pro-Gly-Pro stabilizing tail
- •Russian RCTs report improved cognitive recovery in acute ischemic stroke versus standard care
- •Modulates BDNF and NGF expression and dopaminergic signaling in preclinical models
- •Standard route is intranasal; not FDA approved; research-use-only outside Russia
Side-by-side
| Attribute | Magnesium L-Threonate | Semax |
|---|---|---|
| Category | supplement | peptide |
| Also known as | Mg-T, MgT, Magtein, magnesium threonate | Met-Glu-His-Phe-Pro-Gly-Pro, ACTH(4-10) Pro-Gly-Pro analog |
| Half-life (hr) ↗ | 4 | 0.5 |
| Typical dose (mg) ↗ | 2000 | 0.6 |
| Dosing frequency | 1 to 3 times daily | 2-3x daily (intranasal) |
| Routes | oral | intranasal |
| Onset (hr) | 1 | 0.5 |
| Peak (hr) | 2 | 2 |
| Molecular weight | 294.5 | 813.94 |
| Molecular formula | C8H14MgO10 | C37H51N9O10S |
| Mechanism | 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. | Modulates BDNF and NGF expression in hippocampus and cortex, enhances dopaminergic and serotonergic signaling, and reduces oxidative stress markers in preclinical ischemia models. Lacks corticotropic activity of native ACTH. |
| Legal status | OTC dietary supplement | Approved in Russia for stroke and cognitive disorders; not FDA approved; research-use-only grey market elsewhere |
| WADA status | allowed | unknown |
| DEA / Rx | OTC supplement (not scheduled) | Not FDA approved; not scheduled; research-chemical status outside Russia |
| Pregnancy | Standard magnesium safety; Mg-T-specific data limited | Not recommended; insufficient data |
| CAS | 778571-57-6 | 80714-61-0 |
| PubChem CID | 10691810 | 9811102 |
| Wikidata | Q27151568 | Q4413083 |
Safety profile
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)
Semax
Common side effects
- mild nasal irritation
- transient mild headache
- rare mild euphoria or activation
Contraindications
- pregnancy
- lactation
- acute psychotic disorder
- severe hypertension (caution due to mild activating effect)
Interactions
- stimulants (caffeine, amphetamines): potential additive activation; monitor for overstimulation(minor)
- antipsychotics: theoretical antagonism via dopaminergic modulation(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. Semax is the right call when one of the conditionals below applies.
- → If your priority is sleep onset or sleep quality, pick Magnesium L-Threonate.
- → If your priority is long-term neuroprotection, pick Semax.
- → If your priority is stroke recovery, pick Semax.
Edge case: If you want to avoid research-only / gray-market sourcing, Magnesium L-Threonate is the more accessible choice.
Default choice: Magnesium L-Threonate. Lower friction to source, and broader goal coverage. Reach for Semax 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 Magnesium L-Threonate and Semax?
Magnesium L-Threonate and Semax differ in category (supplement vs peptide), mechanism, and typical dosing. See the side-by-side table for full details.
Which has a longer half-life, Magnesium L-Threonate or Semax?
Magnesium L-Threonate half-life is 4 hours; Semax half-life is 0.5 hours.
Can you stack Magnesium L-Threonate with Semax?
Stack compatibility depends on mechanism overlap, legal status, and individual response. Check each compound page for specific interactions and contraindications before combining.
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