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Immune
Immune-modulating peptide approved in dozens of countries.
Immune
The human body's own antimicrobial peptide, cut from cathelicidin.
Thymosin Alpha-1 is not FDA-approved and rated 4/5 for evidence; LL-37 is not FDA-approved and rated 3/5. Thymosin Alpha-1 has more human evidence behind it. LL-37 is banned in sport by WADA; Thymosin Alpha-1 is not. Both are used for immune goals.
Often used together: A common community immune pairing. No studies of the two together.
| Compare | Thymosin Alpha-1 Immune-modulating peptide approved in dozens of countries. | LL-37 The human body's own antimicrobial peptide, cut from cathelicidin. |
|---|---|---|
| Category | Immune | Immune |
| Evidence | 4/5Multiple RCTs in hepatitis and sepsis; mixed results in sepsis (large trial neutral). | 3/5Small human trials of topical LL-37 for venous leg ulcers; a larger Phase IIb missed its overall goal. No human data for injection. |
| FDA status | Not FDA-approved (approved in ~35 other countries) | Not FDA-approved |
| WADA (sport) | Not on the Prohibited List | Banned |
| Also known as | Tα1, Thymalfasin, Zadaxin | Cathelicidin, hCAP-18 fragment, Ropocamptide |
| How it works | Enhances T-cell maturation and dendritic cell function, modulating innate and adaptive immunity. | A positively charged peptide that disrupts microbe membranes and breaks up biofilms. It also signals immune cells and supports wound closure. The same immune-activating effect is linked to psoriasis, rosacea and lupus when it is overactive. |
| Half-life | About 2 hours | Not established in humans; broken down quickly by proteases |
| Commonly reported doses |
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| Route | Subcutaneous | Subcutaneous |
| Good once mixed | ~14 days in the fridge | ~28 days in the fridge |
| Top side effects |
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| Lowest research-listing price per mg | $2.40 (10 mg vial, 40% off) | $4.20 (5 mg vial, 40% off) |
| Latest lab purity | 99.92% (lot THA0001) | 99.68% (lot LL0002) |
Want a third? Add another peptide. Doses are commonly reported ranges, not recommendations.
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Thymosin Alpha-1 is not FDA-approved and rated 4/5 for evidence; LL-37 is not FDA-approved and rated 3/5. Thymosin Alpha-1 has more human evidence behind it. LL-37 is banned in sport by WADA; Thymosin Alpha-1 is not. Both are used for immune goals.
Thymosin Alpha-1: Not FDA-approved (approved in ~35 other countries). LL-37: Not FDA-approved. Regulations change, so confirm with the FDA.
Thymosin Alpha-1 is rated 4 out of 5: Multiple RCTs in hepatitis and sepsis; mixed results in sepsis (large trial neutral). LL-37 is rated 3 out of 5: Small human trials of topical LL-37 for venous leg ulcers; a larger Phase IIb missed its overall goal. No human data for injection. The scale is explained on our methodology page.
Thymosin Alpha-1 is not named on the WADA list, though the general rule on non-approved substances (S0) can still apply. LL-37 is banned by WADA, by name or as part of a named class.
A common community immune pairing. No studies of the two together. That describes how some people use them, not a recommendation.