Capromorelin
An oral ghrelin agonist originally developed by Pfizer that stimulates growth hormone and appetite.
FDA-approved for veterinary use (Entyce and Elura) and investigated in human trials for age-related muscle wasting and appetite support.
Written by Michael Carroll — Owner, Director of Research · Reviewed by the Peptide Initiative Research Team · Editorial standards
Suggested dose
3 – 10 mg
Compound profile
Capromorelin scientific & efficacy data
Growth Hormone
Peptide profile
Moderate human trials
Capromorelin
3 mg · Once daily
Molecular formula
C28H35N5O4
- Mol. weight
- 505.6 g/mol
- CAS number
- 193273-66-4
- PubChem
- 216208
- Developed · 2001
- Pfizer Global Research and Development (Carpino et al.)
Pfizer Inc.
Amino acid sequence
Sequence not publicly available or proprietaryGH & IGF-1 Stimulation
Potent, dose-dependent growth hormone and IGF-1 elevation through oral ghrelin receptor agonism, supporting anabolic and metabolic pathways
Physical Function
In the pooled treatment groups of a phase 2 trial in older adults, tandem walk improved by 0.9 seconds at 6 months and stair climb improved by 12 months, versus placebo. [1]
Oral Convenience
No injections or reconstitution needed — simple oral capsule with proven bioavailability and predictable pharmacokinetics
Dosing
How much Capromorelin do I take?
3 – 10 mg
3 – 10 mg
Covers all 3 documented dose levels · timing · dose-adjustment guidance.
Every documented dose level
| Phase | Dose | Frequency |
|---|---|---|
| Initial weeks | 3 mg | Twice daily |
| Ongoing | 10 mg | Once daily at bedtime |
| Up to 12 months in the trial | 10 mg | Twice daily |
Suitability
Is Capromorelin right for me?
Best for stimulating growth hormone production in elderly adults & supporting appetite and weight gain in wasting conditions
Best for
Age-Related Muscle Wasting
Capromorelin showed significant improvements in physical function — including tandem walk and stair climb — in elderly adults, making it a strong candidate for combating sarcopenia.
Appetite Stimulation
As an FDA-approved veterinary appetite stimulant, capromorelin has extensive real-world evidence for boosting food intake and body weight in mammals.
Growth Hormone Research
One of the best-studied oral ghrelin agonists with human Phase 2 data, offering researchers a well-characterized tool for studying GH/IGF-1 pathways.
Consider alternatives if
Do not use if
Use with caution if
Not sure?
Compare Capromorelin with similar peptides to find the best fit for your goals.
Administration
How do I use Capromorelin?
Oral (capsule or tablet)
Route
Not applicable — Capromorelin is administered orally only
Best sites
Covers reconstitution · step-by-step technique · storage · a sample daily schedule.
Safety
Is Capromorelin safe?
2 common side effects · 1 serious
Capromorelin was generally well-tolerated in Phase 2 human trials involving nearly 400 elderly participants.
Most side effects were mild to moderate. Its FDA-approved veterinary use provides additional long-term safety data in mammalian species.
Human safety data comes primarily from a single Phase 2 trial (White et al., 2009) with 395 elderly subjects. Extensive veterinary safety data exists from FDA-approved products Entyce (dogs) and Elura (cats).
Less common
These typically resolve with continued use or dose adjustment.
Common side effects · experienced by some users
Appetite stimulation
Increased hunger and food intake. This is the intended mechanism for veterinary use but may be unwanted for some human users. Appetite increase is typically strongest in the first 2-3 weeks, then may stabilize or gradually decrease.
Management: If weight gain is undesired, monitor caloric intake closely and maintain consistent meal timing. Increase protein consumption to support lean muscle development. Consider timing dosing away from meal prep or dining triggers. Drink more water to help with satiety.
Fluid retention and weight gain
Mild to moderate water retention and lean weight gain due to GH effects. May cause temporary increase in body weight, typically 2-5 lbs over a 4-6 week cycle. Most weight gained is lean mass rather than fat, though some water retention is expected.
Management: Monitor body composition rather than just scale weight. Reduce sodium intake slightly to minimize water retention. Maintain adequate hydration. Most fluid retention resolves within 1-2 weeks post-cycle. Use compression garments if peripheral edema is bothersome.
Stop and seek help if
- Severe allergic reaction (rash, swelling, difficulty breathing)
- Significant blood glucose elevation that doesn't normalize
- Persistent nausea, vomiting, or GI distress not relieved by dose adjustment
- Unwanted excessive appetite or weight gain
- Development of peripheral edema or fluid retention
Always consult a healthcare professional before starting or stopping any peptide or research compound. This information is for educational purposes only.
With other peptides
- Safe:GHRH analogs (Sermorelin, Tesamorelin) — Synergistic GH release — GHRH stimulates via a different receptor pathway
- Caution:Other ghrelin agonists (MK-677, GHRP-6) — Redundant mechanism — may not add benefit and could increase side effects
With medications
- Caution:Insulin / Oral hypoglycemics — Capromorelin may elevate blood glucose; monitor closely and adjust diabetes medications as needed
- Caution:Corticosteroids — Both affect glucose metabolism; increased hyperglycemia risk when combined
With supplements
- Safe:Arginine / Ornithine — May modestly enhance GH release when combined with ghrelin agonists
- Safe:Melatonin — Some evidence melatonin supports GH secretion during sleep; generally safe to combine
Effectiveness
How do I know Capromorelin is working?
Moderate human trials · first signs 24-48 hours
Evidence level
Moderate human trials
(Phase 1-2)
Regulatory status
Not approved for human use
FDA-approved for veterinary use only: ENTYCE (appetite stimulation in dogs, 2016) and ELURA (weight loss in cats with chronic kidney disease, 2020); both labels state "not for use in humans".
Onset of effects
Moderate
(1-2 weeks)
How it works
The deeper mechanism
Capromorelin is a selective ghrelin receptor agonist: it binds the growth hormone secretagogue receptor (GHS-R1a) in the hypothalamus, stimulating appetite, and in the pituitary, increasing growth hormone secretion. [4] It binds human GHS-R1a with a Ki of 7 nM.
[6] It is metabolized mainly by CYP3A4 and CYP3A5. In dogs it peaks within about 50 minutes and has a half-life of about 1.2 hours. [4] In older adults, every dose raised peak nocturnal GH (most with the least frequent dosing) and produced a sustained, dose-related rise in IGF-1. [1]
What to expect
24-48 hours
What you might notice
- GH elevation peaks within the first day
- Initial appetite stimulation may begin
What's normal
- Initial response to Capromorelin is beginning at the cellular level
- Different individuals experience Capromorelin's onset at different rates
- Transient systemic effects from initial Capromorelin exposure are common
What's next
- Maintain consistent Capromorelin administration as prescribed
- Document subjective effects and physical markers daily
- Schedule a check-in with your provider about initial observations
1-2 weeks
What you might notice
- IGF-1 levels rise progressively
- Users may notice increased appetite and energy
- Physical performance improvements become apparent
What's normal
- Capromorelin has achieved stable, long-term homeostatic integration
- Sustained efficacy of Capromorelin remains consistent
- Chronic Capromorelin effects remain stable and predictable
What's next
- Maintain your established Capromorelin protocol for sustained benefits
- Continue periodic monitoring to confirm Capromorelin efficacy
- Review comprehensive Capromorelin response with your provider
4-6 weeks
What you might notice
What's normal
- Full therapeutic effects of Capromorelin are well-characterized at this point
- Maintenance of Capromorelin's therapeutic effects is typical
- Tolerance patterns with Capromorelin are generally stable over months
What's next
- Comprehensive assessment of Capromorelin efficacy should be conducted
- Discuss long-term continuation, cycling, or protocol modifications
- Continue regular monitoring of relevant biomarkers or symptoms
Signs it's working
Hormonal
- Elevated IGF-1 on blood work
- Increased GH levels measured 30-90 minutes post-dose
Physical
- Improved appetite and food intake
- Better exercise recovery
- Enhanced muscle tone or strength
Not seeing results? Common reasons
- Dose may be too low — Phase 2 data showed 10-30 mg was needed for meaningful effects
- Not enough time — GH/IGF-1 elevation builds gradually over 1-2 weeks of consistent dosing
- Taking with high-fat meals may alter absorption timing
- Individual variation in ghrelin receptor sensitivity
- Concurrent medications that affect GH axis (e.g., somatostatin analogs) may blunt response
Key research
Questions
Frequently asked about Capromorelin
Is capromorelin FDA-approved for human use?
No. Capromorelin is FDA-approved only for veterinary use: Entyce for dogs (2016) to stimulate appetite, and Elura for cats (2020) to manage weight in chronic kidney disease. Human Phase 2 clinical trials were conducted in elderly subjects showing safety and efficacy, but development for human use was not pursued to FDA approval. It remains a research compound for human applications.
How does capromorelin compare to MK-677 (ibutamoren)?
Both are oral ghrelin agonists that stimulate GH and IGF-1. MK-677 has more human clinical data and is more widely available in research settings. Capromorelin was developed earlier (1999-2001) and has stronger veterinary evidence. Capromorelin has a shorter plasma half-life (1-2.4 hours) compared to MK-677's longer half-life (~24 hours), though both produce sustained GH stimulation. MK-677 may cause more hunger, while capromorelin's appetite effects are more moderate.
Why was capromorelin developed for veterinary use but not pursued for humans?
Capromorelin was developed by Pfizer and showed promise in human Phase 2 trials, but pharmaceutical development is driven by market opportunity and competitive landscape. By the time human efficacy was confirmed, the anti-aging market landscape had shifted. Aratana Therapeutics acquired the veterinary rights and successfully developed it for pet health, which has a clearer regulatory pathway and proven commercial success.
Is capromorelin safe for elderly individuals?
The phase 2 trial randomized 395 adults aged 65–84 to 10 mg three times a week, 3 mg twice a day, 10 mg each night, 10 mg twice a day, or placebo. [1] At 6 months, the pooled treatment groups gained 1.4 kg of body weight and 1.4 kg of lean mass and improved tandem walk; stair climb improved by 12 months. [1] Adverse events included fatigue, insomnia and small rises in fasting glucose, HbA1c and insulin resistance, so glucose should be monitored. [1]
What is the mechanism of action?
Capromorelin is a peptidomimetic ghrelin receptor agonist. It binds to and activates the GHS-R1a (growth hormone secretagogue receptor 1a) on hypothalamic neurons, triggering the release of growth hormone-releasing hormone (GHRH). This stimulates the anterior pituitary to secrete growth hormone, which then stimulates liver IGF-1 production. Additionally, capromorelin activates appetite centers in the hypothalamus, explaining its appetite-stimulating effects used in veterinary practice.
How long is the typical cycle, and is post-cycle therapy needed?
The only human trial planned 2 years of daily dosing; it stopped early, with 315 people completing 6 months and 284 completing 12 months. [1] It did not use short cycles, and no study has tested cycling or post-cycle therapy. GH and IGF-1 effects depend on continued dosing.
Can women use capromorelin?
Capromorelin is not approved for human use, and pregnant and lactating women should avoid it. For non-pregnant women interested in GH stimulation for muscle, bone, or anti-aging purposes, capromorelin theoretically works similarly in both sexes (GH effects are largely sex-neutral). However, given lack of human approval and female-specific safety data, medical supervision would be essential.
Further reading
Capromorelin history & related research
History · since 1999
A tiny molecule that makes hungry animals hungry again
Capromorelin is a small molecule that acts like a hormone messenger. It tells your body to make more growth hormone and feel hungry.
Read the full history of CapromorelinReady for the protocol?
Every dosing tier, administration route, timing note, and dose-adjustment rule for Capromorelin, on one page.