Ipamorelin vs Sermorelin: How They Differ and How to Dose Each

Ipamorelin and sermorelin are often mentioned together because both are studied for their effect on growth hormone release. They are not the same compound, and they do not work the same way. Sermorelin is a GHRH analog. Ipamorelin is a GHRP (a ghrelin receptor agonist). That single mechanism difference is why their typical research dosing ranges, timing, and pairing strategies diverge.

This is a neutral, third-person comparison of how the two differ on paper and how each is commonly reconstituted and measured for lab handling. Nothing here is dosing guidance. Peptides are research compounds not approved for human consumption, and any protocol decision belongs with a licensed clinician. See the disclaimer for the full scope.

Mechanism: GHRH vs GHRP

The pituitary releases growth hormone in response to two upstream signals. Sermorelin and ipamorelin each hit one of them.

• Sermorelin (GHRH analog): binds the GHRH receptor. It mimics the body's own growth-hormone-releasing hormone, the natural starter signal. It is a shortened version of GHRH (the first 29 amino acids), so it carries the active portion of the natural sequence.
• Ipamorelin (GHRP): binds the ghrelin/GHS receptor, a separate pathway. It also suppresses somatostatin, the brake signal that normally limits release. Ipamorelin is noted in research literature for being selective, meaning it has little reported effect on cortisol or prolactin compared to older GHRPs like GHRP-6.

Because they act on two different receptors, the two are described as additive in research settings. That additive effect is the entire reason ipamorelin is so often paired with a GHRH compound rather than run alone.

Why ipamorelin is paired with CJC-1295

Sermorelin and CJC-1295 are both GHRH-side compounds. The practical difference is duration. Sermorelin has a very short half-life, often cited at around 10 to 20 minutes. CJC-1295 (especially the DAC version) is engineered to last far longer, which is why many research stacks pair ipamorelin with CJC-1295 instead of sermorelin: one long-acting GHRH signal plus one GHRP pulse from a single combined vial.

If you are working with that combination, the CJC-1295 and ipamorelin calculator handles the two-peptide reconstitution math in one place so the units line up for each compound in the blend. For background on why the pairing is structured this way, the CJC-1295 ipamorelin dosage reference covers it in more detail.

Typical dosing ranges in research literature

These are commonly cited reference figures from research and compounding contexts, not a recommendation. Units and frequency vary widely by source.

• Sermorelin: commonly referenced around 100 to 300 mcg per administration, often noted before sleep to align with natural GH rhythm.
• Ipamorelin: commonly referenced around 100 to 300 mcg per administration, sometimes split across the day in research protocols because of its short pulse.
• Frequency: both are short-acting, so literature often describes once-daily or more frequent handling. CJC-1295 with DAC is the outlier, designed for far less frequent use.

Note the overlap in mcg figures. The numbers look similar, but they are doing different jobs: sermorelin supplies the GHRH signal, ipamorelin supplies the GHRP pulse. To turn any mcg figure into syringe units you need the vial concentration, which is set at reconstitution.

Reconstitution and measuring units

Both peptides ship as a lyophilized powder and are reconstituted with bacteriostatic water. The math is identical for either compound; only your target mcg changes.

Worked example. A 5 mg (5000 mcg) vial mixed with 2 mL of bacteriostatic water gives a concentration of 2500 mcg/mL. On a U-100 insulin syringe, 1 mL equals 100 units, so the full vial is 100 units of fluid.

• A 250 mcg measure = 250 / 2500 = 0.1 mL = 10 units.
• A 100 mcg measure = 100 / 2500 = 0.04 mL = 4 units.
• A 300 mcg measure = 300 / 2500 = 0.12 mL = 12 units.

Run the same calculation for your own vial size and water volume with the reconstitution calculator, then convert any target to syringe marks with the mg to units calculator. If the unit marks on the barrel are unfamiliar, how to read an insulin syringe for peptides walks through it.

Quick comparison

• Receptor: sermorelin = GHRH receptor. Ipamorelin = ghrelin/GHS receptor.
• Role: sermorelin starts the signal. Ipamorelin amplifies the pulse and lowers the somatostatin brake.
• Selectivity: ipamorelin is cited as selective with minimal reported cortisol or prolactin effect.
• Common pairing: ipamorelin is paired with a GHRH compound (sermorelin or, more often, CJC-1295) because the two pathways are additive.
• Reconstitution math: identical for both. Concentration depends only on vial size and water volume.

Whichever compound a protocol uses, logging the vial concentration, target mcg, and resulting units keeps the numbers consistent over time. The Stackr app stores that per vial so you are not recalculating from scratch each refill.