Peptides  /  LL-37
For Adults · Compounded Peptide

LL-37

A human antimicrobial peptide.

The only human cathelicidin, a naturally occurring antimicrobial peptide studied in innate immunity. Prescribed online after a licensed provider reviews your online visit, compounded by U.S. 503A pharmacies, and shipped discreetly to most U.S. states.

$249

Start your online visit →

A few private questions, then a licensed provider reviews your answers.

100% Online 503A Compounded Licensed Providers Discreet Shipping
ForbiddenRx LL-37 vial
At a glance
Form
Injection
Cadence
Set by your provider
Class
Cathelicidin peptide
Guided by
Provider review
Helps with
Immune category
For
Adults 18+
The basics

What is LL-37?

What it is
Cathelicidin peptide
Forms
Injection
Supplied as
Strength set by your prescriber
Dosing
Set by your prescriber
Supply
1-month
Visit
Online, reviewed by a licensed provider
Prescription
Provider-reviewed · not available OTC
Shipping
Discreet, unmarked · most U.S. states
Start your online visit →

LL-37 is a 37-amino-acid peptide cleaved from the human cathelicidin protein hCAP18. It is part of the innate immune system, is found in skin, airways and white blood cells, and has been studied for its antimicrobial and immune-signalling activity.

Research on LL-37 is mostly laboratory-based, and it has roles in both defence and inflammation. As a compounded injection it is not an FDA-approved medication and has not been shown to treat any infection or condition.

This is a compounded preparation, not an FDA-approved medication, and compounded drugs are not reviewed by the FDA for safety or effectiveness. Individual results are not guaranteed. It is prescribed only where a licensed provider determines it is appropriate after reviewing your health history.

Why people ask about it

Why does LL-37 come up?

LL-37 appears in immune-support conversations because it is the body's own antimicrobial peptide. That biology is well described in the laboratory, but it does not establish a benefit from taking it as a compounded preparation.

✔A provider decides, not a quiz

Every LL-37 prescription here follows a review by a licensed provider of your health history, current medications and goals. If it isn't appropriate for you, it isn't prescribed.

✔Compounded, not a research chemical

Your vial is compounded by a licensed U.S. 503A pharmacy and dispensed against a prescription written in your name — not sold as a "research only" product with no oversight.

Know the difference

Prescribed LL-37 vs. supplements and grey-market vials — what's the difference?

The short answer: unregulated supplements make claims nobody checks, "research only" vials sold online carry no prescription, no pharmacy and no accountability, and a prescribed LL-37 is compounded by a licensed 503A pharmacy against a provider's order written for you.

 Oral supplement"Research only" vialPrescribed LL-37 (Rx)
What it isAn unregulated oral precursorA vial sold without a prescriptionCompounded LL-37 dispensed on a provider's order
Licensed provider reviews youNoNoYes — before anything is dispensed
Compounded by a licensed pharmacyNoNoYes — U.S. 503A
Your name on the vialNoNoYes
Dose set by a prescriberNoNoYes
Legal to sell for human useAs a supplementNoYes — by prescription

The simplest test of any peptide seller: is your name on the vial? A "research only" label means no prescriber reviewed you, no licensed pharmacy compounded it, and nobody is accountable for what is actually inside.

How it works

How does getting LL-37 actually work?

Three steps: answer a short set of medical questions, a licensed provider reviews them, and if they prescribe, a 503A pharmacy compounds and ships it.

I

Answer a few questions

A short private medical questionnaire — your history, current medications and what you are hoping to address. It takes a couple of minutes.

II

Meet your provider live

A provider licensed in your state reviews your answers online — no appointment, no waiting room. They decide whether LL-37 is appropriate.

III

Compounded & shipped

If they prescribe, a licensed U.S. 503A pharmacy compounds your vial and ships it discreetly, with your name on the label.

Who it's for

Who is LL-37 for?

It's for adults who want LL-37 prescribed and compounded properly rather than bought from a grey market. Whether it is appropriate for you is a decision for the provider who reviews your visit.

✔Interested in the immune category

You have read about LL-37 and want it prescribed rather than bought from an unregulated seller.

✔You want a real prescription

Reviewed by a licensed provider, compounded by a 503A pharmacy, dispensed with your name on the vial.

✔You want the dosing decided for you

The amount and schedule are set by your prescriber, not selected here or taken from a forum.

✔You are comfortable with an injectable

LL-37 is compounded as a subcutaneous injection.

✕When it's not the right fit

LL-37 has not been shown to prevent or treat any infection in people, and some research links it to inflammatory skin conditions. If you have an autoimmune or inflammatory condition, tell your provider. It is a compounded preparation, not an FDA-approved medication, and compounded drugs are not reviewed by the FDA for safety or effectiveness. Individual results are not guaranteed. If you are pregnant or breastfeeding, have an active cancer diagnosis, or have significant kidney or liver disease, tell your provider in your answers. New or unexplained symptoms should be evaluated by a clinician rather than self-treated.

How to get it

How do I get LL-37 online?

You answer a few questions, a licensed provider reviews your answers, and — if they prescribe — your medication is compounded and shipped to your door. No insurance required, no in-person appointment, no waiting room.

A few questions

Answer a short set of private medical questions. Add as many peptides as you like; one checkout, and a provider reviews each.

Online provider review

A provider licensed in your state reviews your answers online. Approval is never guaranteed.

Discreet delivery

If prescribed, your vial is compounded by a 503A pharmacy and ships in plain, unmarked packaging to most U.S. states.

Pricing is shown at checkout — no insurance needed, no hidden fees.

Using it & safety

How is it taken, and is it safe?

LL-37 is compounded as injection. The amount and the schedule are set by the provider who reviews your visit — we deliberately do not publish a dosing regimen here, because that is a clinical decision about you, not a product specification.

Forms & how it's taken

Injection
Compounded as injection.
Supplied as
Strength set by your prescriber.
Dose & schedule
Set by your prescriber. Follow the directions on your label.
Supply
1-month supply.
InjectionProvider-set

Safety & side effects

⚠ Not a treatment for infection

LL-37 has not been shown to prevent or treat any infection in people, and some research links it to inflammatory skin conditions. If you have an autoimmune or inflammatory condition, tell your provider. It is a compounded preparation, not an FDA-approved medication, and compounded drugs are not reviewed by the FDA for safety or effectiveness. Individual results are not guaranteed.

Reported effects are most often related to the injection itself or to infusing too quickly. They can include:

  • Redness, swelling or itching at the injection site
  • Headache
  • Fatigue

Tell your provider about every condition and medication before starting, including pregnancy or breastfeeding. Stop and seek care for signs of an allergic reaction — rash, swelling of the face or throat, or difficulty breathing. For emergencies call 911.

Compare your options

Which skin and repair peptide fits you?

A side-by-side look at the skin & repair options available through ForbiddenRx. Which one is appropriate for you is decided by the provider who reviews your visit.

TreatmentWhat it isFocusFormForRx required
LL-37
This page		Cathelicidin peptideImmune categoryInjectionAdults 18+Yes
BPC-157Synthetic pentadecapeptideRepair categoryInjectionAdults 18+Yes
BPC-157 CapsulesSynthetic pentadecapeptideRepair categoryCapsulesAdults 18+Yes
GHK-CuCopper tripeptideSkin & repair categoryInjectionAdults 18+Yes
Questions, answered

LL-37 FAQ

What is LL-37?

LL-37 is the human cathelicidin antimicrobial peptide, part of the innate immune system.

Can it treat an infection?

No. It has not been shown to treat or prevent any infection. See a clinician for any suspected infection.

Is it FDA-approved?

No. It is a compounded preparation, not an FDA-approved medication, and compounded drugs are not reviewed by the FDA for safety or effectiveness. Individual results are not guaranteed.

Do I have to book an appointment?

No. You complete the questionnaire online and a licensed provider reviews it — there is no scheduling step and no waiting room.

Can I order more than one peptide?

Yes. Add each one to your cart and check out once. A provider reviews every treatment in your order.

Credibility you can verify

Care held to a higher standard

Licensed Providers

U.S. board-certified clinicians

503A Pharmacies

U.S.-based compounding partners

Most U.S. States

We confirm your state during intake

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Category

The Peptide Catalog

Every peptide we can dispense, each prescribed by a licensed provider and compounded by a 503A pharmacy.

Learn more →

Start with a real prescription

If you are going to take LL-37, take one a licensed provider prescribed and a 503A pharmacy compounded with your name on it. Answer a few questions and a licensed provider reviews them.

Start your online visit →

  • Discreet, unmarked packaging
  • Refills so you never miss a dose
  • Labs guiding every adjustment
  • Licensed providers in most U.S. states
Medically reviewed

Sources & references

Medically reviewed by ForbiddenRx Medical Affairs — Independent, licensed medical providers · Last reviewed August 2026. This page was written and is periodically reviewed for medical accuracy in line with clinical guidance followed by the independent, licensed medical providers in the ForbiddenRx network. It is provided for general educational purposes and is not a substitute for professional medical advice, diagnosis, or treatment. Always talk with a licensed provider about your individual health.

  1. PubMed — LL-37 human cathelicidin, review literature.
  2. PubMed — cathelicidin LL-37 and innate immunity, published literature.
  3. U.S. Food & Drug Administration. 503A Pharmacy Compounding — the regulatory basis for how this preparation is dispensed.
For further reading

Clinical references

This page is educational and is not medical advice.