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The Peptide Effect
Comparison

CJC-1295 vs Sermorelin

CJC-1295 and sermorelin are both GHRH analogs that stimulate pituitary growth hormone release, but they represent different generations of peptide engineering. Sermorelin is bioidentical GHRH(1-29) — the minimal active fragment of native GHRH — with decades of clinical history and a former FDA approval. CJC-1295 is a modified GHRH analog with amino acid substitutions for protease resistance, and its DAC (Drug Affinity Complex) variant extends the half-life from minutes to approximately 8 days by binding serum albumin. This pharmacokinetic difference is the key distinction: CJC-1295 allows less frequent dosing and produces more sustained GH/IGF-1 elevation, while sermorelin creates shorter, more physiologic GH pulses.

Side-by-side comparison diagram of CJC-1295 and Sermorelin mechanisms of action
Conceptual comparison — not to scale

Head-to-Head Comparison

CriteriaCJC-1295Sermorelin
Primary mechanismGHRH receptor agonist — modified GHRH analog with enhanced stabilityGHRH receptor agonist — bioidentical GHRH(1-29) fragment
Amino acid modifications4 amino acid substitutions (Ala2, Gln8, Ala15, Leu27) for protease resistance; optional DAC conjugationNone — identical to first 29 amino acids of native human GHRH
Half-life~30 minutes (no DAC / Mod GRF 1-29); ~8 days (with DAC)~10–20 minutes
Dosing frequency1–3× daily (no DAC); 1–2× weekly (with DAC)Once daily before bed (standard protocol)
Typical dosage100 mcg (no DAC) per injection; 2 mg (with DAC) per weekly injection200–300 mcg subcutaneous per injection
GH release patternPulsatile (no DAC) or sustained elevation (with DAC)Short pulsatile GH release that closely mimics natural GHRH signaling
IGF-1 elevationSignificant and sustained — CJC-1295 DAC shown to raise IGF-1 by 65–115% in clinical trialsModerate and transient — IGF-1 increases during active treatment, normalizes quickly after discontinuation
FDA historyNo FDA approval; investigational compound with clinical trial dataPreviously FDA-approved (Geref) for pediatric GH deficiency diagnostics; brand discontinued
Clinical data depthModerate — Phase I/II trials demonstrating GH/IGF-1 elevation and safetyExtensive — decades of clinical use, multiple published studies, former FDA-approved drug
Side effectsInjection site irritation, water retention, facial flushing, transient numbness/tingling; DAC version may cause prolonged side effects due to long half-lifeMild — injection site reactions, facial flushing, headache; effects resolve quickly due to short half-life
Ease of course correctionNo DAC: quick clearance allows easy adjustment. With DAC: 8-day half-life means side effects persist if they occurExcellent — 10–20 minute half-life means any adverse effects resolve very rapidly
Approximate monthly cost$50–$100 (research grade); $200–$450 (clinic)$50–$100 (compounding); $200–$400 (clinic)

When to Choose Each

Choose CJC-1295

Users who want less frequent dosing (especially DAC variant), those seeking maximum sustained IGF-1 elevation, protocols where dosing compliance is a concern, experienced peptide users comfortable with longer-acting compounds

Choose Sermorelin

First-time peptide users who want the most conservative option, physician-supervised protocols that prioritize clinical history and safety data, users who want rapid clearance for easy dose adjustment, those who prefer bioidentical compounds

Verdict

For users who want the convenience of less frequent dosing and maximum sustained GH/IGF-1 elevation, CJC-1295 with DAC is the superior choice — one or two injections per week versus daily dosing. For users who prioritize the most natural GH release pattern, a well-characterized safety profile, and easy course correction if issues arise, sermorelin is the safer and more conservative option with decades of clinical backing. In practice, many clinics have moved toward CJC-1295 (without DAC, also known as Mod GRF 1-29) as the preferred GHRH component in stacks with ipamorelin, as it offers better stability than sermorelin without the extended-release concerns of the DAC variant.

References

  1. Prolonged stimulation of growth hormone (GH) and insulin-like growth factor I secretion by CJC-1295, a long-acting analog of GH-releasing hormone, in healthy adults (2006) — PubMed
  2. The effect of CJC-1295, a synthetic GHRH analog, on pulsatile GH secretion (2006) — PubMed
  3. Sermorelin: a review of its use in the diagnosis and treatment of children with idiopathic growth hormone deficiency (1999) — PubMed
  4. Growth hormone-releasing hormone: clinical studies and therapeutic aspects (1988) — PubMed
  5. Pharmacokinetics and pharmacodynamics of modified GRF(1-29) and its DAC-conjugated analog (2006) — PubMed

Frequently Asked Questions

What is Mod GRF 1-29 and how does it relate to CJC-1295?
Mod GRF 1-29 is CJC-1295 without the DAC (Drug Affinity Complex) modification. It has the same 4 amino acid substitutions for protease resistance but lacks the albumin-binding DAC group, giving it a half-life of about 30 minutes instead of 8 days. In the peptide community, "CJC-1295 no DAC" and "Mod GRF 1-29" are used interchangeably. This is the version most commonly stacked with ipamorelin.
Should I choose CJC-1295 with DAC or without DAC?
CJC-1295 without DAC (Mod GRF 1-29) is generally preferred for daily stacking protocols with ipamorelin because it creates a pulsatile GH pattern similar to natural physiology. The DAC version is better for those who want maximum convenience (weekly dosing) and sustained IGF-1 elevation, but the constant GH stimulation is less physiologic and may lead to more water retention. Most anti-aging clinicians recommend the non-DAC version.
Is sermorelin outdated compared to CJC-1295?
Not necessarily. Sermorelin has a weaker pharmacokinetic profile (shorter half-life, no protease resistance) but its bioidentical nature and extensive safety record make it preferred by many physicians. It is still one of the most commonly prescribed GH peptides in anti-aging medicine. CJC-1295 (no DAC) is technically a better-engineered molecule, but "better" depends on whether you prioritize stability or a proven clinical track record.
Can I switch from sermorelin to CJC-1295 mid-protocol?
Yes — since both act on the same GHRH receptor, switching is straightforward. No washout period is necessary. Many users start with sermorelin to establish tolerance and then transition to CJC-1295 (no DAC) for improved stability and potency. If stacking with ipamorelin, simply replace the GHRH component while keeping the ipamorelin dose unchanged.
Do CJC-1295 or sermorelin require refrigeration and special storage?
Both peptides require careful storage to maintain potency. As lyophilized (freeze-dried) powders before reconstitution, they are generally stable at room temperature for limited periods but are best stored in a refrigerator. Once reconstituted with bacteriostatic water, both should be refrigerated at 2 to 8 degrees Celsius (36 to 46 degrees Fahrenheit) and are typically considered stable for 3 to 4 weeks. CJC-1295 has somewhat better inherent stability than sermorelin due to its protease-resistant amino acid substitutions. Avoid freezing reconstituted peptides and protect them from direct sunlight. Consulting the supplier for specific storage guidelines is recommended.

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