LL-37 (Cathelicidin) vs Semax

Side-by-side comparison of mechanisms, dosing, interactions, and stacking potential.

LL-37 (Cathelicidin)Semax
CategoryPeptidesPeptides
Standard DoseResearch indicates 50-100 mcg daily via subcutaneous injection for immune support.Research indicates 200-600 mcg daily via intranasal administration (0.1% solution, 2-3 drops per nostril).
TimingMorning administration preferred for immune support. Topical application directly to wound sites.Morning and early afternoon dosing (avoid evening — may cause stimulation/insomnia). Intranasal preferred for rapid CNS delivery.
Cycle Duration4-8 week cycles. Short-term use preferred due to limited long-term safety data.10-14 day cycles with equal rest periods. Some protocols use 3-5 day on / 2 day off patterns.
Evidence Levelanimal_plus_anecdotalmoderate_human

Mechanism

LL-37 is a 37-residue amphipathic helical antimicrobial peptide, the only human cathelicidin, that kills bacteria by forming tetrameric channels that perforate cytoplasmic membranes. Beyond direct antimicrobial activity, it modulates innate immunity through formyl-peptide receptor 2 (FPR2), induces chemotaxis of neutrophils and monocytes, upregulates CXCR4 and IL-8, and neutralizes bacterial endotoxins (LPS). It also promotes wound healing through keratinocyte migration and angiogenesis.

Standard Dosing

Research indicates 50-100 mcg daily via subcutaneous injection for immune support.

Timing

Morning administration preferred for immune support. Topical application directly to wound sites.

Cycle Duration

4-8 week cycles. Short-term use preferred due to limited long-term safety data.

Side Effects

  • Injection site pain and redness
  • Localized inflammation
  • Potential mast cell activation

Contraindications

  • Active autoimmune conditions (particularly lupus — LL-37 is implicated in SLE pathophysiology)
  • Pregnancy and breastfeeding
  • Psoriasis (may exacerbate)

Best Stacking Partners

KPVThymosin Alpha-1BPC-157
B

Semax

Peptides

Mechanism

Semax (Met-Glu-His-Phe-Pro-Gly-Pro) is a synthetic heptapeptide analog of the ACTH(4-10) fragment that rapidly upregulates brain-derived neurotrophic factor (BDNF) and its signaling receptor TrkB in the hippocampus (1.4-fold BDNF protein increase, 3-fold exon III BDNF mRNA increase). It activates dopaminergic and serotonergic brain systems, enhances neurotrophin gene expression (BDNF, NGF), and modulates intracellular calcium dynamics in brain neurons. Semax lacks ACTH's corticotropic activity, acting purely as a nootropic/neuroprotective agent.

Standard Dosing

Research indicates 200-600 mcg daily via intranasal administration (0.1% solution, 2-3 drops per nostril).

Timing

Morning and early afternoon dosing (avoid evening — may cause stimulation/insomnia). Intranasal preferred for rapid CNS delivery.

Cycle Duration

10-14 day cycles with equal rest periods. Some protocols use 3-5 day on / 2 day off patterns.

Side Effects

  • Nasal irritation (intranasal route)
  • Mild headache
  • Stimulation/insomnia if dosed late
  • Irritability at high doses
  • Hair loss (anecdotal at high doses)

Contraindications

  • Seizure disorders
  • Acute psychosis or mania
  • Pregnancy and breastfeeding
  • Severe hypertension

Best Stacking Partners

SelankP21Noopept

Not sure which is right for you?

Take our free assessment to get personalized recommendations based on your health goals, current stack, and biomarkers.

Get Your Free Protocol →or take the assessment →