Side-by-side · Research reference
TesamorelinvsThymosin α-1
Side-by-side comparison across mechanism, dosage, evidence, side effects, administration, and stack synergies. Citations on every claim where available.
AFDA-ApprovedVerified27/68 cited
BPhase 3Reviewed8/39 cited
Tesamorelin
GHRH Analogue · FDA-Approved
SQ · Abdomen · Once Daily
Thymosin α-1
Immune modulator · Approved (some countries)
SQ · 2× weekly · 6+ months for chronic indications
01Mechanism of Action
Parameter
Tesamorelin
Thymosin α-1
Primary target
Hypothalamic GHRH receptorsEGRIFTA® (tesamorelin for inje 2010
Toll-like receptor 9 (TLR9) + T-cell maturation pathwayCamerini 2001
Pathway
GHRH → Pituitary GH release → Liver IGF-1 synthesisFalutz 2007
TLR9 activation → ↑ IFN-α + IL-2 + IFN-γ → enhanced T-cell function + dendritic cell maturationIyer 2007
Downstream effect
Increased GH pulsatility, elevated IGF-1, lipolysis of visceral adipose tissueFalutz 2010
Restored T-cell function, improved viral clearance, anti-tumour adjuvant effectsIyer 2007
Feedback intact?
Yes — physiological pulsatility preserved
—
Origin
Synthetic 44-AA GHRH analogue with trans-3-hexenoic-acid modification for stabilityEGRIFTA® (tesamorelin for inje 2010
Synthetic 28-AA peptide identical to natural Tα-1 isolated from thymus extractCamerini 2001
02Dosage Protocols
Parameter
Tesamorelin
Thymosin α-1
Frequency
Once daily (morning or pre-sleep)
Aligns with natural GH pulse.
2× weekly (Mon/Thu typical)
Lower / starter dose
1 mg / dayFalutz 2010
1 mg still produces significant IGF-1 elevation.
0.8 mg per injection
Evidence basis
RCT / FDA-approvedFalutz 2007Falutz 2010
Phase 3 + approved (35+ countries as Zadaxin)Iyer 2007
Duration
12–52 weeks
VAT returns within months of stopping.
6–12 months for chronic indications
Reconstitution
Sterile water per labeling
Preserved at 2–8 °C after reconstitution.
Sterile water for injection per vial label
Timing
Empty stomach, pre-sleep preferred
No specific time
Half-life
~26 min (plasma)EGRIFTA® (tesamorelin for inje 2010
Modified vs native GHRH (7 min t½).
~2 hours plasma; tissue effect days
03Metabolic / Fat Loss Evidence
Parameter
Tesamorelin
Thymosin α-1
Primary fat target
Visceral adipose tissue (VAT) — abdominal
—
Effect on lean mass
Modest lean mass preservation / slight increase
—
Effect reversibility
VAT returns within months of stopping
—
Key publication
Falutz et al. NEJM 2007 · Falutz JCEM 2010 · FDA approval 2010Falutz 2007Falutz 2010EGRIFTA® (tesamorelin for inje 2010
—
04Side Effects & Safety
Parameter
Tesamorelin
Thymosin α-1
Injection site reaction
Erythema, pruritus, redness (common)
Erythema, mild discomfort
Fluid retention / Edema
Peripheral edema, arthralgia, carpal tunnel (GH-axis effect)
—
IGF-1 elevation
Dose-dependent; supraphysiological levels = discontinue
—
Cancer risk
Contraindicated in active malignancy (GH/IGF-1 axis); theoretical tumour growth riskEGRIFTA® (tesamorelin for inje 2010
No signal — used as adjuvant in oncology
Antibody formation
~50% at 26 weeks; non-neutralising in most; rare hypersensitivity (<1%)Sévigny 2018
—
GI symptoms
Nausea, diarrhea (mild, transient)
Rare nausea
Fatigue
—
Common during initial weeks
Fever / flu-like
—
Mild interferon-like response possible
Autoimmune
—
Theoretical risk; caution in active autoimmune disease
Absolute Contraindications
Tesamorelin
- ·Active malignancy or history of treated cancer
- ·Pregnancy
- ·Hypersensitivity to tesamorelin or mannitol
- ·Disruption of hypothalamic-pituitary axis (trauma, tumour, radiation)
Thymosin α-1
- ·Pregnancy / breastfeeding
- ·Hypersensitivity to peptide
- ·Concurrent immunosuppressant therapy (transplant patients)
Relative Contraindications
Tesamorelin
- ·Untreated diabetes (monitor HbA1c)
- ·Severe carpal tunnel syndrome
- ·Acute critical illness
Thymosin α-1
- ·Active autoimmune disease
- ·Severe immunocompromised state without supervision
05Administration Protocol
Parameter
Tesamorelin
Thymosin α-1
1. Reconstitution
Add 2.1 mL sterile water to 2 mg lyophilised vial. Roll gently — do not shake. Solution should be clear.
Add 1 mL sterile water per 1.6 mg vial → 1.6 mg/mL.
2. Injection site
Subcutaneous — abdomen preferred. Rotate sites (avoid same spot within 2 cm). Avoid navel and waistband area.
SQ — abdomen, thigh, or upper arm. Rotate sites.
3. Timing
Once daily. Preferred: evening, 2–3 hrs post-meal, before sleep — aligns with natural GH secretion pulse.
2× weekly, e.g. Monday + Thursday.
4. Storage
Lyophilised: room temp, light-protected. Reconstituted: refrigerate 2–8 °C, use within 21 days.
Lyophilised: refrigerate. Reconstituted: refrigerate, use within 24 h.
5. Needle
27–31G, 4–8 mm insulin syringe. Pinch skin, 45° angle for lean individuals.
27–31G, 4–8 mm insulin syringe.
06Stack Synergy
Tesamorelin
+ Ipamorelin
StrongTesamorelin (GHRH analogue) and ipamorelin (GHRP / ghrelin mimetic) act on two distinct receptor systems to amplify GH release synergistically — GHRH receptor + ghrelin receptor. This dual-axis stimulation produces a more robust, sustained GH pulse than either alone while maintaining physiological pulsatility. Ipamorelin is highly selective with minimal cortisol or prolactin elevation, making it the preferred GHRP pairing.
- Tesamorelin
- 2 mg SQ · evening
- Ipamorelin
- 200–300 mcg SQ · same injection
- Frequency
- Once daily, pre-sleep
- Primary benefit
- Maximal GH pulsatility, fat loss, recovery, sleep quality
Thymosin α-1
— no documented stacks