Tabimorelin
An investigational oral growth hormone secretagogue that stimulates GH release through ghrelin receptor activation, though development was discontinued due to drug interaction concerns.
Written by Michael Carroll — Owner, Director of Research · Reviewed by the Peptide Initiative Research Team · Editorial standards
Suggested dose
1.5 mg/kg
Compound profile
Scientific & efficacy data
Growth Hormone
Peptide profile
Moderate human trials
Tabimorelin
1.5 mg/kg per day (3 mg/kg first and last dose) · Once daily
Molecular formula
C32H40N4O3
- Mol. weight
- 528.7 g/mol
- CAS number
- 193079-69-5
- PubChem
- 9810101
- Developed · 1999
- Novo Nordisk Research Team
Novo Nordisk A/S
Amino acid sequence
N/A — Non-peptide small molecule (peptidomimetic growth hormone secretagogue)Growth Hormone Stimulation
Potent, dose-dependent GH elevation starting at 1.5 mg/kg; significant IGF-1 increases at higher doses, supporting anabolism and GH-mediated benefits
Convenience & Compliance
Non-injection, oral formulation enhances user compliance and avoids injection-site reactions; suitable for extended-use protocols
Selectivity & Safety Profile
Does not significantly elevate prolactin, cortisol, or ACTH at most doses; however, CYP3A4 inhibition and rapid tolerance development limit overall safety and efficacy profile
Dosing
How much do I take?
1.5 mg/kg · once daily
1.5 mg/kg
Once daily
Covers timing · dose-adjustment guidance.
Suitability
Is this right for me?
Best for stimulating growth hormone production in healthy individuals & exploring gh secretagogue mechanisms in research settings
Do not use if
Use with caution if
Not sure?
Compare Tabimorelin with similar peptides to find the best fit for your goals.
Administration
How do I use it?
Oral (capsule or solution)
Route
Not applicable — oral formulation only
Best sites
Covers reconstitution · step-by-step technique · storage.
Safety
Is it safe?
5 common side effects · 1 serious
Tabimorelin is an oral GHS-R agonist with preclinical and early clinical data indicating dose-dependent appetite stimulation (potentially problematic for weight-conscious users) and transient blood glucose elevation due to GH's insulin-antagonistic effects.
No human safety database exists beyond Phase 1/2 studies—efficacy and long-term safety profile in humans remain incompletely characterized.
Potential risks include carpal tunnel syndrome (documented with chronic GH therapy), arthralgias, and theoretical tumor growth acceleration, though these are extrapolated from GH physiology rather than directly observed in limited human exposure.
Safety information is limited to rat and limited human Phase 1/2 data; no Phase 3 efficacy trials have been completed. GH secretagogue class effects (appetite stimulation, glucose dysregulation) are expected based on mechanism, but individual tolerability variability is substantial.
Long-term human safety data beyond 12 weeks does not exist—any use should be considered experimental with careful clinical monitoring including fasting glucose and IGF-1 levels.
Common side effects · experienced by some users
Headache
Mild to moderate headache onset within 1-2 hours of dosing, typically frontal or temporal. Reported in ~30% of users in early clinical trials. Usually improves with repeated dosing as body tolerates ghrelin stimulation.
Management: Take with food to slow absorption and reduce intensity. Ibuprofen or acetaminophen (500 mg) effective if needed. Stay well-hydrated—dehydration worsens headaches. Divide dose (AM + PM instead of single dose) if tolerated. Most headaches diminish by day 3-5 with continued use.
Nausea
Mild to moderate nausea onset within 30 minutes to 2 hours post-dose. Reflects ghrelin receptor stimulation in the chemoreceptor trigger zone. Reported in ~20-25% of users. Usually mild and self-limited but can be distressing.
Management: Take immediately after eating (not on empty stomach) to buffer gastric irritation. Ginger (500 mg capsule or tea) is highly effective and natural. Ondansetron (4-8 mg) or metoclopramide (10 mg) work if ginger insufficient. Ensure adequate hydration. Most users report nausea resolves by day 3-5 as chemoreceptor tolerance develops.
Appetite stimulation
Ghrelin mimicry causes progressive appetite increase starting day 2-3. Peak hunger typically days 7-14. Mediated via NPY/AgRP pathways in lateral hypothalamus. Expected and intended effect reflecting proper ghrelin receptor activation.
Management: If weight gain is undesired, portion control at meals is essential—use smaller plates and eat slowly. Increase protein proportion to promote satiety. Avoid keep snacks available in visible locations. Time dosing away from peak hunger (early morning on empty stomach, not pre-meal). Increase aerobic activity to offset caloric surplus. This effect usually stabilizes by week 3-4.
Dizziness
Mild to moderate lightheadedness or vertigo onset within 30-90 minutes post-dose. Likely reflects acute cardiovascular changes from GH stimulation and ghrelin receptor activation. Usually mild and transient.
Management: Avoid driving or operating heavy machinery for 1-2 hours after dosing. Sit or lie down if dizziness occurs. Stay well-hydrated. Slow positional changes—rise from sitting slowly. Blood pressure monitoring may reveal mild changes. Dizziness usually diminishes by day 2-3 as tolerance develops.
Dry mouth
Xerostomia develops gradually within 1-4 hours post-dose. Results from ghrelin receptor stimulation affecting salivary gland function and increased metabolic rate. Usually mild but can be bothersome.
Management: Increase overall fluid intake to 2.5-3 liters daily. Sip water frequently throughout day. Sugar-free gum/lozenges stimulate saliva production. Avoid caffeinated beverages (worsen dehydration). Mouth rinse with water before bed. Most cases resolve by day 3-7 with consistent hydration.
Stop and seek help if
- Severe or worsening side effects that don't improve with dose adjustment or supportive care
- Signs of an allergic reaction—rash, hives, swelling, or difficulty breathing
- Your healthcare provider recommends discontinuation based on your clinical response
- Development of any new medical condition that may be contraindicated with Tabimorelin
- Pregnancy or planning to become pregnant (unless specifically approved for use during pregnancy)
- Abnormal lab results or clinical markers that suggest adverse effects
Tabimorelin should only be started, adjusted, or discontinued under medical supervision. This information is for educational purposes only and does not replace professional medical advice. Never stop a prescribed treatment without consulting your healthcare provider first, as abrupt discontinuation may have consequences.
With other peptides
- Safe:GHRH (synergistic GH stimulation, though not extensively studied in humans) — May be used together under medical guidance.
- Safe:Resistance training (enhances GH-mediated muscle growth) — May be used together under medical guidance.
- Safe:Adequate protein intake and overall nutrition (supports GH-driven anabolism) — May be used together under medical guidance.
With medications
- Caution:Strong CYP3A4 inhibitors (itraconazole, ritonavir, clarithromycin) — tabimorelin itself inhibits CYP3A4, creating bidirectional interaction risks — Use with caution—discuss with your healthcare provider.
- Caution:CYP3A4 substrates (statins, certain antiarrhythmics, immunosuppressants) without careful monitoring — Use with caution—discuss with your healthcare provider.
With supplements
- Safe:Multivitamins — Generally safe to take alongside Tabimorelin. Space doses apart if taking oral formulations to ensure optimal absorption.
- Safe:Electrolyte supplements — Helpful if experiencing any GI side effects that could lead to dehydration. Safe to combine.
Effectiveness
How do I know it's working?
Moderate human trials · first signs first dose
Evidence level
Moderate human trials
(Phase 1-2)
Regulatory status
Research compound
Onset of effects
Moderate
(1-2 weeks)
How it works
Tabimorelin is a growth hormone secretagogue peptide that stimulates your pituitary gland to release more growth hormone.
It works by binding to ghrelin receptors in the brain and pituitary, triggering natural growth hormone pulses. This helps increase muscle mass, bone density, and metabolic rate while reducing fat accumulation.
The deeper mechanism
Tabimorelin is a synthetic growth hormone-releasing peptide (GHRP) that selectively binds to and activates the ghrelin receptor (GHSR-1a) located on somatotroph cells in the anterior pituitary gland and on GHRH neurons in the hypothalamus.
This binding activates Gq/11 G protein-coupled receptor signaling pathways, leading to increased intracellular calcium mobilization and activation of PKC signaling cascades.
In somatotrophs, GHSR-1a activation directly stimulates growth hormone (GH) release through enhanced exocytosis of GH granules.
Simultaneously, Tabimorelin activates hypothalamic GHRH neurons while inhibiting somatostatin (SRIF)-secreting neurons, creating a dual mechanism for enhanced GH secretion.
The peptide also exhibits modest appetite-stimulating properties through NPY/AgRP pathway activation in the lateral hypothalamus. Unlike exogenous GH injection which suppresses endogenous GH secretion through negative feedback, Tabimorelin maintains natural pulsatile GH secretion patterns.
What to expect
First dose
What you might notice
- GH elevation occurs within 30–60 minutes;
- peak typically at 60–90 minutes post-dose
What's normal
- Full integration of Tabimorelin into physiological systems is established
- Long-term Tabimorelin response remains personalized to your physiology
- Tabimorelin tolerance is well-maintained with consistent dosing
What's next
- Maintain your established Tabimorelin protocol for sustained benefits
- Continue periodic monitoring to confirm Tabimorelin efficacy
- Review comprehensive Tabimorelin response with your provider
Days 1–3
What you might notice
- Mild headache, nausea, or dizziness may emerge;
- appetite begins to increase
What's normal
- Tabimorelin is achieving sufficient receptor engagement
- Initial mechanism of Tabimorelin is taking effect
- Early transient effects from Tabimorelin administration are resolving
What's next
- Maintain consistent Tabimorelin administration as prescribed
- Document subjective effects and physical markers daily
- Schedule a check-in with your provider about initial observations
Days 4–7
What you might notice
- Continued GH elevation on each dose;
- tolerance may begin to develop in some individuals (seen clinically as reduced GH peak)
What's normal
- Tabimorelin is achieving sufficient receptor engagement
- Initial mechanism of Tabimorelin is taking effect
- Early transient effects from Tabimorelin administration are resolving
What's next
- Maintain consistent Tabimorelin administration as prescribed
- Document subjective effects and physical markers daily
- Schedule a check-in with your provider about initial observations
Weeks 2–4
What you might notice
- Sustained appetite stimulation;
- modest gains in muscle or lean mass possible with adequate protein and training;
- GH response plateaus or declines in some users
What's normal
- Tabimorelin is now achieving steady-state pharmacokinetics
- Measurable changes aligned with Tabimorelin's mechanism may appear
- Initial adjustment effects typically resolve by this point
What's next
- Maintain Tabimorelin dosing exactly as established
- Track progress toward intended outcomes in detail
- Review lab work or biomarker changes with your healthcare team
Weeks 4–6
What you might notice
- End of typical cycle;
- benefits plateau or decline as tolerance fully develops;
- discontinuation recommended per protocol
What's normal
- Tabimorelin is now achieving steady-state pharmacokinetics
- Measurable changes aligned with Tabimorelin's mechanism may appear
- Initial adjustment effects typically resolve by this point
What's next
- Maintain Tabimorelin dosing exactly as established
- Track progress toward intended outcomes in detail
- Review lab work or biomarker changes with your healthcare team
Days after discontinuation
What you might notice
- GH levels return to baseline within 24–48 hours;
- appetite normalizes;
- no rebound adverse effects
What's normal
- Tabimorelin response patterns are emerging
- Initial Tabimorelin response is consistent with mechanism expectations
- Early tolerance development to Tabimorelin is not expected
What's next
- Assess whether Tabimorelin response aligns with expectations
- Plan next steps based on initial Tabimorelin tolerance and response
- Establish baseline monitoring for Tabimorelin response tracking
Not seeing results? Common reasons
- Not at therapeutic dose yet—initial doses are for building tolerance, not maximum effect
- Insufficient time at target dose—most compounds need several weeks to show full benefits
- Inconsistent dosing schedule—regular, consistent use is crucial for optimal results
- Individual variation in response—genetics, metabolism, and other factors affect outcomes
- Underlying conditions or medications interfering with absorption or effectiveness
- Improper storage leading to degraded product—always verify proper storage conditions
Key research
Questions
Frequently asked
Is tabimorelin the same as ghrelin?
No. Tabimorelin is a synthetic, non-peptide small molecule (peptidomimetic) that mimics ghrelin's effects by binding to the ghrelin receptor. Ghrelin is the natural hormone produced by stomach cells. Tabimorelin is stronger and longer-lasting than native ghrelin.
Why was tabimorelin development discontinued?
Development was halted primarily due to tabimorelin's mechanism-based inhibition of CYP3A4, a major liver enzyme. This creates serious drug-drug interaction risks—tabimorelin can dangerously elevate levels of medications metabolized by CYP3A4 (statins, some immunosuppressants, certain antiarrhythmics, etc.). Additionally, clinical trials showed limited efficacy in GH-deficient patients, with only 11% achieving meaningful GH peaks, combined with rapid tolerance development.
How quickly does tolerance develop to tabimorelin?
Clinical data show that GH response declines significantly after just 1 week of continuous daily dosing in many individuals, a phenomenon called tolerance. This is why most protocols recommend cycling: 4–6 weeks on, 2–3 weeks off, or using intermittent dosing schedules.
Can I safely combine tabimorelin with my cholesterol medication (statin)?
This is a serious concern. Tabimorelin inhibits CYP3A4, the enzyme that metabolizes most statins. Combining them could raise statin levels dangerously, increasing risk of muscle breakdown (rhabdomyolysis) or liver injury. You MUST consult a physician and pharmacist before combining. Switching to a statin not metabolized by CYP3A4 (e.g., pravastatin, rosuvastatin) may be necessary.
Is tabimorelin available as a commercial product?
No. Tabimorelin (NN-703) never received FDA approval and development was discontinued. It is not commercially available in any country and is only available within research or investigational settings.
How does tabimorelin compare to other growth hormone secretagogues like MK-677 or ipamorelin?
All three are non-peptide ghrelin receptor agonists. Tabimorelin is highly selective for GHSR and potently stimulates GH, but carries significant CYP3A4 inhibition risks. MK-677 (Ibutamoren) has a better drug-interaction profile and is more widely used. Ipamorelin is another oral alternative with less published CYP3A4 liability. Tabimorelin's development was discontinued due to the drug-interaction risk.
Further reading
History & related research
History · since 1998
The Danish pill that almost beat the peptide
Tabimorelin is a peptidomimetic drug created by Novo Nordisk. It mimics how peptides work but comes as an easy-to-swallow pill.
Read the full history of TabimorelinReady for the protocol?
Every dosing tier, administration route, timing note, and dose-adjustment rule for Tabimorelin, on one page.