Liothyronine (T3) vs Semax
FDA Approved vs Well Studied
monitor Mechanism-based · 51% Both Liothyronine (T3) and Semax can raise blood pressure. Monitor BP regularly and consider adding cardiovascular support (cardarine, telmisartan, or similar).
Molecular Data
Liothyronine (T3) Semax
Weight 650.97 Da 813.93 Da
Half-life ~1 day 0.5-2 hours
Chain — 7 amino acids
Type Thyroid hormone (C15H12I3NO4) ACTH(4-10) synthetic analog
Key Benefits
Liothyronine (T3)
01 Direct and rapid increase in basal metabolic rate
02 Enhanced fat oxidation and lipolysis
03 Improved energy levels and reduction of hypothyroid fatigue
04 Faster-acting than T4 with effects noticeable within hours to days
05 Useful when peripheral T4-to-T3 conversion is impaired (illness, caloric deficit, stress)
06 Supports body temperature regulation and thermogenesis
07 Can improve cognitive clarity and reduce brain fog associated with low thyroid function
Semax
01 Rapid brain delivery via intranasal route
02 Rapidly increases BDNF levels
03 Extensive clinical research in Russia
04 Easy self-administration
05 Modulates dopamine and serotonin systems
06 Neuroprotective effects
Dosing Protocols
Liothyronine (T3)
25-75 mcg/day (replacement) / 1-2x daily (oral)
Semax
300-600mcg per dose (up to 1000mcg for intensive use) / 1-2x daily (morning recommended for cognitive boost)
Research protocol 500-750mcg 1x daily
Intensive protocol 750-1000mcg 1-2x daily
Side Effects
Liothyronine (T3)
Tachycardia and palpitations (increased heart rate, especially at higher doses)
Anxiety, nervousness, and irritability
Insomnia and disrupted sleep architecture
Increased sweating and heat intolerance
Tremor (fine hand tremor, similar to hyperthyroid presentation)
Increased appetite despite accelerated metabolism
Loose stools or increased bowel frequency
Semax
Mild nasal discomfort (nasal route)
Possible nasal sensation upon administration
Contraindications
Untreated adrenal insufficiency (must correct cortisol deficiency before starting T3)
Acute myocardial infarction or unstable angina
Thyrotoxicosis or untreated hyperthyroidism
Known hypersensitivity to liothyronine or any tablet excipients
Uncorrected adrenal cortical insufficiency (risk of adrenal crisis)
Pregnancy or breastfeeding
Known peptide allergies
Do not exceed 4-week continuous use without medical supervision
Research Evidence
Liothyronine (T3) Semax
Status FDA Approved Well Studied
References 5 studies 5 studies
Latest September 2023 2025
FDA Approved Yes No
This comparison is for educational and research purposes only. Consult a healthcare professional before use.