Is Thymosin Alpha-1 FDA approved?

Thymosin Alpha-1 (Zadaxin) is approved in 35+ countries for viral hepatitis and immune reconstitution, but is not FDA-approved in the United States. It is used off-label and available as a research chemical domestically.

What dose of LL-37 is used in research?

Research protocols typically use 25–50mg/week subcutaneously for systemic antimicrobial and immunomodulatory effects. Topical use for wound infections uses lower concentrations in peptide-formulated dressings. For research use only.

LL-37 vs Thymosin Alpha-1: Dosing, Half-Life, Side Effects + Which to Choose (2026) | PeptiDex

Quick Verdict

LL-37 for direct antimicrobial action — destroys biofilms and pathogens on contact. Thymosin Alpha-1 for immune system calibration — trains T-cells to mount better responses. Use LL-37 to kill the infection; use TA1 to strengthen your immune system against future threats.

Side-by-Side Analysis

Dimension	LL-37	Thymosin Alpha-1
Mechanism	The only human cathelicidin antimicrobial peptide.	Enhances T-cell function, boosts dendritic cell activity, and modulates cytokine production.
Primary Benefits	Broad-spectrum antimicrobial, anti-biofilm, wound healing, immune modulation, anti-inflammatory	Immune support, antiviral, recovery
Typical Dose	100–100mcg	1500–1500mcg
Route	SubQ	SubQ
Frequency	7x/wk	2x/wk
Half-Life	4 hours	2 hours
FDA Status	Approved	Approved
Evidence Grade	moderate	moderate-strong
Key Studies	20+ indexed	20+ indexed
Lowest Price	$94.97 / 5mg via Bio Longevity Labs	$78.00 / 10mg via Ascension Peptides

Which one should you choose?

LL-37 is a direct antimicrobial agent that attacks pathogens, while Thymosin Alpha-1 (TA1) is an immune modulator that trains your body to fight infections itself. LL-37 binds to and breaks down the membranes of bacteria, viruses, and biofilms, making it highly effective against active, stubborn infections (like Lyme or SIBO). TA1 enhances the function of T-cells and dendritic cells, balancing an underactive or overactive immune system. Choose LL-37 as a targeted "smart bomb" for a specific chronic infection. Choose TA1 for long-term immune support, viral clearance, or autoimmune modulation. TA1 is the safer, more fundamental default.

Who Should Choose LL-37?

Choose LL-37 if you:

Have an active chronic infection (Lyme, SIBO, biofilm-forming bacteria)
Need direct antimicrobial and antiviral action at the infection site
Are researching wound infections or antimicrobial-resistant bacteria
Want a peptide that also modulates LPS-induced inflammation

Who Should Choose Thymosin Alpha-1?

Choose Thymosin Alpha-1 if you:

Have an underactive or dysregulated immune system
Are recovering from chemotherapy or immunosuppression
Want to improve vaccine efficacy or T-cell function
Are researching autoimmune modulation or viral clearance (Hepatitis B/C, COVID)

Can you stack LL-37 + Thymosin Alpha-1?

Synergistic combination. LL-37 directly targets and destroys the pathogen; Thymosin Alpha-1 enhances the adaptive immune response to finish the job and prevent recurrence. This combination is used in integrative medicine for stubborn chronic infections.

Vendor Pricing

· Affiliate links · Prices verified 2026

LL-37

1 vendor

Bio Longevity LabsTriple-Tested Best Value

5mg vial · $18.99/mg

$94.97Buy

Full vendor comparison for LL-37

Thymosin Alpha-1

2 vendors

Ascension Peptides Best Value

10mg vial · $7.80/mg

$78.00Buy

Bio Longevity Labs

10mg vial · $13.00/mg

$129.97Buy

Full vendor comparison for Thymosin Alpha-1

Affiliate disclosure: PeptiDex may earn a commission from purchases via vendor links at no extra cost to you. See our methodology.

Frequently Asked Questions

LL-37 has broad-spectrum antimicrobial activity and can disrupt beneficial bacteria if overused or misapplied. For systemic subcutaneous use at research doses, disruption of the gut microbiome is minimal as it does not reach the gut lumen at therapeutic concentrations.

Deep Dive Profiles

LL-37 Research Profile Thymosin Alpha-1 Research Profile

Research Tools

PK Plasma Curves

Visualize LL-37 & Thymosin Alpha-1 plasma concentration over time

Reconstitution Calculator

Calculate precise dilution volumes and concentrations

Research Use Only — Not Medical Advice

This comparison is provided for educational and research purposes only. It does not constitute medical, prescribing, or treatment advice. Clinical data cited here is sourced from published peer-reviewed trials and FDA labels. Consult a qualified healthcare professional before making any decisions about medications or research compounds. PeptiDex is an informational resource and does not sell pharmaceutical products.