What Is Sermorelin? Dosage, Half-Life & How to Track It

What Sermorelin is and how it works

Sermorelin is a synthetic peptide corresponding to the first 29 amino acids of natural growth-hormone-releasing hormone (GHRH) — the shortest fragment of the full 44-amino-acid hormone that retains its biological activity. It binds the same GHRH receptor on the pituitary, prompting it to release growth hormone in a pulse, exactly the way the body’s own GHRH does.

It was actually the first peptide in this GHRH-analog family to reach the market: the FDA approved it in 1997 under the brand name Geref, primarily for diagnosing and treating pediatric growth-hormone deficiency. The brand was discontinued for commercial reasons — not safety — years ago, but the peptide itself is chemically identical to what was in that product.

Because it stimulates the pituitary rather than replacing GH directly, it preserves the natural feedback loop: somatostatin can still cap the pulse, which is the same reason it is commonly paired with a GHRP like ipamorelin — that combination reliably produces a bigger release than either alone.

Typical dosing & reconstitution

Sermorelin is reconstituted from lyophilized powder with bacteriostatic water. A common titration is 200 mcg nightly for the first couple of weeks, building to 300–500 mcg by week 5–8, always dosed at bedtime.

Vial size and BAC water set concentration, which sets your units:

At 1.67 mg/mL, a 300 mcg dose is 18 units. The larger 3 mL dilution keeps most doses comfortably above 10 units for accurate reading on a standard insulin syringe — the reconstitution calculator does this math for any vial size.

Half-life & what it means for frequency

Sermorelin clears extremely fast — its half-life is on the order of 10–20 minutes, in line with natural GHRH itself. That brief window is exactly what makes it a once-daily peptide rather than something dosed less often: there is no depot, so the pulse it produces is over quickly and the next one has to be a fresh injection.

The corollary is that timing is everything. Dosed at bedtime, it rides the body’s largest natural GH pulse of the day; dosed at the wrong time or on a full stomach, the response is weaker. There is no long tail to worry about, but there is also no room for a "close enough" schedule.

What to track & common side effects

Sermorelin is generally well tolerated. The most common complaints are injection-site redness, a brief flush or warmth after the dose, and occasional headache. Because it is dosed at bedtime, some people report vivid dreams or lighter sleep in the first week or two, which usually settles.

Since it is a nightly habit sustained over months, what is worth tracking is simple: the bedtime streak, sleep quality, and whatever recovery or body-composition marker you started it for — plus IGF-1 if you lab it periodically to see whether the trend is moving.

Frequently asked questions