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Thymosin Alpha-1 vs LL-37 side-by-side

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Thymosin Alpha-1LL-37

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Property	Thymosin Alpha-1	LL-37
Category	Immune	Immune
Also known as	Ta1, Zadaxin, thymalfasin	Cathelicidin, CAP18
FDA approved	No	No
Clinical status	Approved in 30+ countries as Zadaxin; not FDA approved in the United States; source also reports FDA orphan drug designation and expected Category 1 compounding status return in 2026. Pre Preclinical I Phase I II Phase II III Phase III IV Phase IV FDA FDA approved	Investigational; source notes clinical trials for wound healing and FDA Category 2 restricted status due to limited safety data and immunogenicity concerns. Pre Preclinical I Phase I II Phase II III Phase III IV Phase IV FDA FDA approved
What to expect	Immune support, chronic infections, cancer adjunct	Antimicrobial, infections, biofilm disruption, wound healing
How it works	Thymosin Alpha-1 is presented as an immune modulator. The supplied evidence describes activity at toll-like receptors, particularly TLR9 and TLR2, on dendritic cells. That pathway is linked in the source to Th1-oriented T-cell signaling, natural killer cell activity, antibody response effects, and regulatory T-cell activity through IDO-associated signaling.	LL-37 is described as a positively charged, amphipathic host-defense peptide that can associate with negatively charged microbial membranes and disrupt them. Beyond direct antimicrobial effects, the source reports signaling roles that include neutralizing bacterial LPS, shaping inflammatory activity, recruiting immune cells to sites of injury or infection, and supporting epithelial repair. The source notes production in epithelial tissues such as skin, gut, and lung, as well as immune cells including neutrophils.
Typical dosing	1.6 mg twice weekly · 2-3x weekly	100-200 mcg daily · Once daily
Research dosing	1.6 mg twice weekly · 6-12 months for hepatitis · Subcutaneous injection	100-200 mcg subcutaneous · Variable by protocol · Subcutaneous injection or topical
Typical duration	6-12 months for hepatitis	Variable by protocol
Administration	Subcutaneous injection	Subcutaneous injection or topical
Timing	Morning With or without food	Morning With or without food
Evidence level	Clinical Trials	Clinical Trials
Possible side effects	Injection site reactions (Reported as the most common side effect in the source.) Mild fatigue (Reported in the supplied side-effect list.) Headache (Reported in the supplied side-effect list.) +3 more Rare allergic reactions (Reported as rare in the source.) Contraindicated in immunosuppressed transplant patients (Listed by the source as a contraindication rather than a routine adverse effect.) Favorable safety profile (General safety characterization reported by the source, not a specific adverse event.)	Injection-site reactions (Reported as common in the source.) Skin toxicity (Source examples include ulcers and burning.) Allergic reactions (Reported by the source without severity grading.) +4 more Histamine release (Source flags caution for MCAS or histamine sensitivity.) Possible contribution to autoimmune conditions (Reported as a potential concern, not established causality.) High-dose toxicity concerns (Source flags concern at higher doses.) Limited long-term safety data (Source notes uncertainty around longer-term safety.)
Research summary	The source reports a substantial human research base for Thymosin Alpha-1, including use in chronic hepatitis B and safety observations across more than 30 trials with over 11,000 participants. Evidence in sepsis is described as mixed: an earlier ETASS study suggested lower 28-day mortality, while the larger double-blind TESTS phase 3 trial in 1,106 patients did not show a mortality benefit. The source also notes study as an adjunct in selected cancers and vaccine-response contexts, but characterizes that support as weaker.	The source presents LL-37 as a well-studied endogenous component of human innate immunity, with literature support for broad antimicrobial activity, membrane disruption, and distribution across epithelial and immune tissues. It also reports exploratory research on LL-37 or related mimics in laboratory anticancer models, Helicobacter pylori host-defense research, and ocular-surface pathogen contexts. The evidence described is strongest for LL-37 as a natural immune peptide; deliberate administration remains experimental in the supplied source, and the source flags that LL-37 may worsen inflammation in some disease settings.
References	PubMed PMC +2 more PMC Springer	Peptibase peptides Peptibase peptides +3 more Peptibase peptides Peptibase peptides Peptibase peptides
Full profile	View Details	View Details

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Educational use only. This information is aggregated from public research and community reports. It is not medical advice, and dosing details are descriptive, not recommendations. Always consult a qualified healthcare professional.

Property

Thymosin Alpha-1

LL-37

Category

Immune

Also known as

Ta1, Zadaxin, thymalfasin

Cathelicidin, CAP18

FDA approved

Clinical status

Approved in 30+ countries as Zadaxin; not FDA approved in the United States; source also reports FDA orphan drug designation and expected Category 1 compounding status return in 2026.

Pre
Preclinical
I
Phase I
II
Phase II
III
Phase III
IV
Phase IV
FDA
FDA approved

Investigational; source notes clinical trials for wound healing and FDA Category 2 restricted status due to limited safety data and immunogenicity concerns.

Pre
Preclinical
I
Phase I
II
Phase II
III
Phase III
IV
Phase IV
FDA
FDA approved

What to expect

Immune support, chronic infections, cancer adjunct

Antimicrobial, infections, biofilm disruption, wound healing

How it works

Thymosin Alpha-1 is presented as an immune modulator. The supplied evidence describes activity at toll-like receptors, particularly TLR9 and TLR2, on dendritic cells. That pathway is linked in the source to Th1-oriented T-cell signaling, natural killer cell activity, antibody response effects, and regulatory T-cell activity through IDO-associated signaling.

LL-37 is described as a positively charged, amphipathic host-defense peptide that can associate with negatively charged microbial membranes and disrupt them. Beyond direct antimicrobial effects, the source reports signaling roles that include neutralizing bacterial LPS, shaping inflammatory activity, recruiting immune cells to sites of injury or infection, and supporting epithelial repair. The source notes production in epithelial tissues such as skin, gut, and lung, as well as immune cells including neutrophils.

Typical dosing

1.6 mg twice weekly · 2-3x weekly

100-200 mcg daily · Once daily

Research dosing

1.6 mg twice weekly · 6-12 months for hepatitis · Subcutaneous injection

100-200 mcg subcutaneous · Variable by protocol · Subcutaneous injection or topical

Typical duration

6-12 months for hepatitis

Variable by protocol

Administration

Subcutaneous injection

Subcutaneous injection or topical

Timing

Morning

With or without food

Morning

With or without food

Evidence level

Clinical Trials

Possible side effects

Injection site reactions (Reported as the most common side effect in the source.)
Mild fatigue (Reported in the supplied side-effect list.)
Headache (Reported in the supplied side-effect list.)

+3 more

Rare allergic reactions (Reported as rare in the source.)
Contraindicated in immunosuppressed transplant patients (Listed by the source as a contraindication rather than a routine adverse effect.)
Favorable safety profile (General safety characterization reported by the source, not a specific adverse event.)

Injection-site reactions (Reported as common in the source.)
Skin toxicity (Source examples include ulcers and burning.)
Allergic reactions (Reported by the source without severity grading.)

+4 more

Histamine release (Source flags caution for MCAS or histamine sensitivity.)
Possible contribution to autoimmune conditions (Reported as a potential concern, not established causality.)
High-dose toxicity concerns (Source flags concern at higher doses.)
Limited long-term safety data (Source notes uncertainty around longer-term safety.)

Research summary

The source reports a substantial human research base for Thymosin Alpha-1, including use in chronic hepatitis B and safety observations across more than 30 trials with over 11,000 participants. Evidence in sepsis is described as mixed: an earlier ETASS study suggested lower 28-day mortality, while the larger double-blind TESTS phase 3 trial in 1,106 patients did not show a mortality benefit. The source also notes study as an adjunct in selected cancers and vaccine-response contexts, but characterizes that support as weaker.

The source presents LL-37 as a well-studied endogenous component of human innate immunity, with literature support for broad antimicrobial activity, membrane disruption, and distribution across epithelial and immune tissues. It also reports exploratory research on LL-37 or related mimics in laboratory anticancer models, Helicobacter pylori host-defense research, and ocular-surface pathogen contexts. The evidence described is strongest for LL-37 as a natural immune peptide; deliberate administration remains experimental in the supplied source, and the source flags that LL-37 may worsen inflammation in some disease settings.

References

PubMed PMC

+2 more

PMC Springer

Peptibase peptides Peptibase peptides

+3 more

Peptibase peptides Peptibase peptides Peptibase peptides

Full profile

View Details