Liothyronine (T3) vs PT-141
FDA Approved vs FDA Approved
monitor Mechanism-based · 60% Both Liothyronine (T3) and PT-141 can raise blood pressure. Monitor BP regularly and consider adding cardiovascular support (cardarine, telmisartan, or similar).
Molecular Data
Liothyronine (T3) PT-141
Weight 650.97 Da —
Half-life ~1 day ~2.7 hours
Type Thyroid hormone (C15H12I3NO4) Melanocortin receptor agonist
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
PT-141
01 FDA-approved pharmaceutical route
02 Predictable absorption profile
03 Effective for both male and female sexual dysfunction
04 Works within 45 minutes
05 Effective in PDE5 inhibitor-resistant cases
06 Central mechanism (not dependent on blood flow)
Dosing Protocols
Liothyronine (T3)
25-75 mcg/day (replacement) / 1-2x daily (oral)
PT-141
Women: 1.75mg (FDA-approved); Men: 1-2mg; Start 0.5mg test dose for tolerance / As needed before sexual activity; max 1 dose per 24 hours
Female HSDD (FDA-approved) 1.75mg As needed, max 1 dose/24hr
Male Erectile Dysfunction 1-2mg As needed, 45-60min before activity
Female Arousal Disorder 0.75-1.25mg As needed, max 1 dose/24hr
Low Starting Dose 0.5mg Test dose for tolerance assessment
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
PT-141
Nausea (40%)
Flushing (20%)
Headache (11%)
Injection site reactions
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)
Uncontrolled hypertension
Cardiovascular disease
Use of nitrate medications
Pregnancy or breastfeeding
Research Evidence
Liothyronine (T3) PT-141
Status FDA Approved FDA Approved
References 5 studies 4 studies
Latest September 2023 2022
FDA Approved Yes Yes
This comparison is for educational and research purposes only. Consult a healthcare professional before use.