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
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
- Academic research consortium
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
Improved balance, muscle strength, and stair-climbing ability demonstrated in Phase 2 elderly trials at 10-30 mg doses
Oral Convenience
No injections or reconstitution needed — simple oral capsule with proven bioavailability and predictable pharmacokinetics
Dosing
How much do I take?
3 – 10 mg
3 – 10 mg
Covers all 3 documented dose levels · timing · dose-adjustment guidance.
Suitability
Is this 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 it?
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 it 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).
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.
Less common
These typically resolve with continued use or dose adjustment.
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 it's working?
Moderate human trials · first signs 24-48 hours
Evidence level
Moderate human trials
(Phase 1-2)
Regulatory status
FDA approved for this use
Onset of effects
Moderate
(1-2 weeks)
How it works
Capromorelin is a small molecule that acts like the natural growth hormone-releasing hormone (GHRH) in your body.
It binds to receptors in the pituitary gland to stimulate the release of growth hormone, which increases muscle mass, bone strength, and energy levels. It's especially useful for improving appetite and helping people maintain muscle as they age.
The deeper mechanism
Capromorelin exerts its effects through specific receptor-mediated signaling pathways. At the molecular level, the peptide binds to its target receptor, triggering a cascade of intracellular events including second messenger activation and downstream gene expression changes.
The resulting physiological effects reflect the integrated output of these signaling cascades across relevant target tissues. Further research continues to elucidate the complete mechanism of action and identify potential therapeutic applications.
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
- Full effects manifest including muscle mass increase, improved body composition, and enhanced physical capacity
- Optimal cycle length for clinical efficacy
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
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?
Yes, with appropriate monitoring. The Phase 2 clinical trial (White et al., 2009) enrolled 395 elderly subjects aged 65+ and found capromorelin to be generally well-tolerated. The 10 mg and 30 mg doses produced significant improvements in tandem walk and stair climb tests. However, elderly individuals should be monitored for diabetes risk, fluid retention, and joint effects, particularly those with existing metabolic disorders.
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?
Human clinical trials used 4-6 week cycles. Since capromorelin works through natural physiological pathways (ghrelin signaling), formal post-cycle therapy isn't typically necessary. However, GH levels return to baseline when dosing stops. For those doing extended use, periodic breaks (1-2 weeks off per month) may allow the body to maintain sensitivity to ghrelin signaling. Consult with a healthcare provider for personalized cycling advice.
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.
What is the oral bioavailability, and does food affect absorption?
Capromorelin has good oral bioavailability as a small-molecule compound. Food may modestly reduce absorption speed but not necessarily total bioavailability. For optimal GH stimulation, taking capromorelin in the morning on an empty stomach is often recommended, similar to other GH secretagogues. However, it can be taken with food if needed for GI tolerance.
Further reading
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.