What is the recommended Ghrelin dosage?

Ghrelin dosing varies by experience level. Beginners typically start at 50mcg daily, moderate users at 100mcg 2x daily, and aggressive protocols use 200mcg 2x daily.

How do you reconstitute Ghrelin?

Ghrelin typically comes in 5mg vials. Add 2mL of bacteriostatic water to the vial. Use our free calculator for exact syringe units based on your desired dose.

What is the half-life of Ghrelin?

The half-life of Ghrelin is ~30 minutes (IV), ~60-90 minutes (SC). This determines how frequently you need to dose for consistent blood levels.

Ghrelin

MetabolicInjectionResearchGrade B~30 minutes (IV), ~60-90 minutes (SC) half-life

Appetite StimulationGrowth Hormone ReleaseCachexiaGastric MotilityEnergy Homeostasis8 weeks on / 4 weeks off

Benefits

Potent stimulation of growth hormone release via the GHS-R1a receptor

Appetite stimulation — useful in cachexia, anorexia, and wasting conditions

Enhanced gastric motility and gastroprokinetic effects

Neuroprotective properties observed in preclinical models

Anti-inflammatory effects in various tissue models

Cardioprotective signaling through AMPK-dependent pathways

Improved body composition in catabolic states

Half-Life

~30 minutes

Route

Injection

Frequency

Daily

Vial Sizes

5mg

BAC Water

2mL

Safety Grade

Grade B

Open Ghrelin Dosage Calculator

Calculate exact syringe units for your vial and dose

About Ghrelin

Ghrelin is a 28-amino-acid peptide hormone discovered in 1999 as the endogenous ligand of the growth hormone secretagogue receptor (GHS-R1a). Uniquely among mammalian peptides, it carries an octanoyl (C8 fatty acid) modification on its third serine residue, which is essential for receptor binding and biological activity. Produced primarily by enteroendocrine cells in the stomach fundus, ghrelin is the only known circulating orexigenic (appetite-stimulating) hormone. It plays a central role in energy homeostasis by stimulating appetite, promoting growth hormone release from the anterior pituitary, regulating gastric motility, and modulating glucose metabolism. Ghrelin levels rise before meals and fall after eating, earning it the designation as the "hunger hormone."

Who Should Consider Ghrelin

Adults with cancer-related cachexia or anorexia seeking appetite restoration
Patients with functional dyspepsia or gastroparesis requiring prokinetic support
Elderly individuals with sarcopenia or age-related appetite decline
Adults with growth hormone deficiency being evaluated with GH stimulation testing
Researchers studying energy homeostasis, reward signaling, or GH secretion

How Ghrelin Works

Ghrelin binds to the growth hormone secretagogue receptor type 1a (GHS-R1a), a G-protein-coupled receptor expressed in the hypothalamus, pituitary, and throughout the gastrointestinal tract. At the pituitary, GHS-R1a activation triggers Gq/11-mediated signaling, raising intracellular calcium and stimulating growth hormone release independently of GHRH. In the arcuate nucleus of the hypothalamus, ghrelin activates NPY/AgRP neurons while inhibiting POMC/CART neurons, producing a strong orexigenic drive. The octanoyl modification at Ser3 — catalyzed by the enzyme ghrelin O-acyltransferase (GOAT) — is required for GHS-R1a binding. Ghrelin also activates vagal afferents in the gut to enhance gastric motility and acid secretion, and engages AMPK in peripheral tissues to promote fatty acid oxidation and glucose sparing.

What to Expect

First dose

0-2 hours

Rapid increase in circulating GH levels within 15-30 minutes. Noticeable hunger and appetite stimulation within 30-60 minutes. Possible mild flushing. Effects wane within 2-3 hours due to short half-life.

Days 1-7

Consistent appetite increase when dosed pre-meal. GH pulses become more predictable. Some users report improved sleep quality. Possible mild water retention and increased food intake.

Weeks 2-4

Measurable increase in caloric intake and body weight in cachectic populations. Improved gastric emptying rates. IGF-1 levels may begin to rise. Fat-free mass may start improving in catabolic patients.

Weeks 4-8

Clinical studies show meaningful weight gain in cachexia patients (1-3 kg). Sustained GH elevation with continued dosing. Body composition shifts toward lean mass preservation. Some GHS-R1a tachyphylaxis may begin to appear.

Weeks 8+

Receptor desensitization may reduce GH-releasing efficacy. Cycling off for 4 weeks is recommended to restore sensitivity. Appetite effects may partially persist. Long-term safety data beyond 12 weeks is limited.

Dosing Protocol

Level	Dose / Injection	Frequency
Beginner	50mcg	Daily
Moderate	100mcg	2x Daily
Aggressive	200mcg	2x Daily

Note: Endogenous 28-amino-acid orexigenic hormone with octanoyl modification at Ser3. Natural ligand of GHS-R1a. Primarily secreted by gastric oxyntic cells. Rapid degradation by esterases — acylated form is the bioactive species. Not widely available as a research peptide; MK-677, GHRP-2, and GHRP-6 are more commonly used synthetic GHS-R agonists.

How to Inject Ghrelin

Inject subcutaneously into the abdominal area or thigh. For appetite stimulation, administer 30-60 minutes before meals. For GH release, administer on an empty stomach, ideally in the morning or before sleep. Rotate injection sites. Due to the short half-life, multiple daily doses may be needed to sustain effects. Reconstitute lyophilized powder with bacteriostatic water along the vial wall; swirl gently, do not shake.

Cycling Protocol

On Period

8 weeks

Off Period

4 weeks

Due to potential GHS-R1a desensitization with chronic exposure, cycling is recommended. Clinical research protocols typically use acute or short-term dosing. Monitor appetite, weight, and fasting glucose during on periods.

Pharmacokinetics

Half-Life

30min

Bioavailability

SC: estimated ~50-70%; rapid des-acylation by plasma esterases reduces active fraction

Tmax

~15-30 minutes (IV bolus), ~60 minutes (SC)

Data Confidence

moderate

Source: IV half-life ~30 min; SC half-life estimated at 60-90 min based on acyl-ghrelin clearance kinetics (PMID 15191344)

Pharmacokinetics — Active Dose Over Time

Loading the interactive decay curve.

Side Effects

Increased appetite and potential weight gain are the most common effects. Transient flushing, mild nausea, and diarrhea may occur. Elevated blood glucose due to GH-mediated insulin resistance has been observed at higher doses. Increased gastric acid secretion possible. Water retention and mild edema reported in some clinical studies. Injection site reactions (redness, swelling) are possible with subcutaneous administration.

Contraindications

Active malignancy — ghrelin may promote tumor growth through GHS-R1a expressed on some cancer cell lines
Uncontrolled diabetes mellitus — ghrelin raises blood glucose via GH-mediated insulin resistance and direct hepatic effects
Pregnancy or breastfeeding — no safety data available in these populations
Prader-Willi syndrome — already characterized by elevated ghrelin and hyperphagia
Active eating disorders (binge eating disorder, bulimia) — appetite stimulation is contraindicated
Known hypersensitivity to ghrelin or any excipients

Drug Interactions

Insulin and oral hypoglycemics — ghrelin increases blood glucose; may require dose adjustment of diabetes medications
Exogenous growth hormone — additive GH elevation; increased risk of IGF-1-related side effects
Somatostatin analogs (octreotide, lanreotide) — directly oppose ghrelin-mediated GH release; reduced efficacy
GLP-1 receptor agonists (semaglutide, liraglutide) — opposing appetite effects may negate ghrelin's orexigenic action
Corticosteroids — both ghrelin and glucocorticoids raise blood glucose; additive hyperglycemia risk
Atropine and anticholinergics — may blunt ghrelin's gastroprokinetic effects