Peptide half-lives range from 2 minutes (GnRH) to 5 to 7 days (semaglutide, CJC-1295 with DAC), and understanding these numbers determines how often you need to dose each compound. Short half-life peptides like ipamorelin (2 hours) and GHRP-6 (15 to 20 minutes) require daily or multiple daily injections, while long half-life peptides like tirzepatide (5 days) and semaglutide (7 days) work with once-weekly dosing. Half-life also affects how quickly a peptide clears your system, which matters for anti-doping testing, side effect management, and switching between protocols. The chart below covers over 30 commonly used peptides with their half-lives, typical dosing schedules, and clinical notes.
Key takeaways
- Half-life determines dosing frequency: peptides with half-lives under 30 minutes typically need multiple daily doses, while those over 24 hours may work with weekly injections
- Semaglutide (168 hours) and tirzepatide (120 hours) have the longest half-lives among commonly prescribed peptides, enabling once-weekly dosing
- BPC-157 has an estimated half-life of 4 to 6 hours, supporting once or twice daily dosing for most protocols
- Modified peptides (PEGylated, acylated) often have dramatically longer half-lives than their unmodified versions
- Individual factors like kidney function, body composition, and injection site affect actual clearance rates by 20 to 40%
Complete peptide half-life reference chart
This chart organizes peptides by category with half-life, typical dosing frequency, and route of administration. Half-life values come from published pharmacokinetic studies where available, and from manufacturer data or clinical estimates where formal PK studies haven't been published.
| Peptide | Half-life | Dosing frequency | Route |
|---|---|---|---|
| GLP-1 receptor agonists | |||
| Semaglutide | ~168 hours (7 days) | Once weekly | SC injection |
| Tirzepatide | ~120 hours (5 days) | Once weekly | SC injection |
| Liraglutide | ~13 hours | Once daily | SC injection |
| Exenatide (extended) | ~2 weeks (sustained release) | Once weekly | SC injection |
| Dulaglutide | ~120 hours (5 days) | Once weekly | SC injection |
| Healing and tissue repair peptides | |||
| BPC-157 | ~4 to 6 hours (estimated) | Once or twice daily | SC injection or oral |
| TB-500 (thymosin beta-4 fragment) | ~6 to 8 hours | Twice weekly (loading), once weekly (maintenance) | SC injection |
| GHK-Cu | ~30 to 60 minutes (plasma) | Once or twice daily | SC injection or topical |
| KPV | ~2 to 3 hours (estimated) | Once or twice daily | SC injection or oral |
| Pentosan polysulfate (Cartrophen) | ~24 hours | Once weekly | SC/IM injection |
| Growth hormone secretagogues | |||
| Ipamorelin | ~2 hours | Once to three times daily | SC injection |
| CJC-1295 without DAC (Mod GRF 1-29) | ~30 minutes | Once to three times daily | SC injection |
| CJC-1295 with DAC | ~5 to 8 days | Once or twice weekly | SC injection |
| Sermorelin | ~10 to 20 minutes | Once daily (before bed) | SC injection |
| Tesamorelin | ~26 to 38 minutes | Once daily | SC injection |
| GHRP-2 | ~25 to 30 minutes | Two to three times daily | SC injection |
| GHRP-6 | ~15 to 20 minutes | Two to three times daily | SC injection |
| Hexarelin | ~70 minutes | Once to twice daily | SC injection |
| MK-677 (ibutamoren, non-peptide) | ~4 to 6 hours (but IGF-1 elevated 24h) | Once daily (oral) | Oral |
| Melanocortin and cosmetic peptides | |||
| PT-141 (bremelanotide) | ~2 to 3 hours | As needed (45 min before activity) | SC injection |
| Melanotan II | ~33 to 56 minutes | Loading: daily. Maintenance: 1 to 2x/week | SC injection |
| Hormonal and reproductive peptides | |||
| GnRH (gonadotropin-releasing hormone) | ~2 to 4 minutes | Pulsatile (every 60 to 120 min) | IV/SC pump |
| Gonadorelin | ~4 minutes | Two to three times weekly | SC injection |
| Kisspeptin-10 | ~28 minutes (IV), ~55 min (SC) | Variable (research stage) | IV or SC |
| Oxytocin | ~3 to 5 minutes (IV) | As prescribed | IV, IM, intranasal |
| Anti-inflammatory and immune peptides | |||
| Thymosin alpha-1 | ~2 hours | Two to three times weekly | SC injection |
| LL-37 | ~4 to 6 hours (estimated) | Once daily or three times weekly | SC injection |
| AOD-9604 | ~30 to 45 minutes | Once daily | SC injection or oral |
| Insulin and metabolic peptides | |||
| Insulin lispro (rapid-acting) | ~1 hour | With meals | SC injection |
| Insulin glargine (long-acting) | ~12 to 24 hours | Once daily | SC injection |
Why does peptide half-life matter for your protocol?
Half-life determines three things that directly affect your results: how often you inject, how stable your blood levels are, and how quickly a peptide clears your system.
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Try the BMI Calculator →Short half-life peptides (under 30 minutes) like sermorelin and GHRP-6 require precise timing. They create sharp peaks followed by rapid clearance, which actually mimics the body's natural pulsatile hormone release. This is why sermorelin is given before bed: it triggers a GH pulse that coincides with your natural nighttime GH surge, amplifying the effect. The short half-life means the peptide is gone within 2 hours, avoiding sustained GH elevation that could cause side effects.
Long half-life peptides like semaglutide (168 hours) and CJC-1295 with DAC (5 to 8 days) maintain more consistent blood levels. This is useful for applications requiring steady-state concentrations, such as appetite suppression with GLP-1 agonists. The STEP 1 trial (Wilding et al., New England Journal of Medicine, 2021) showed 14.9% mean body weight loss with once-weekly semaglutide, a result enabled by its 7-day half-life maintaining consistent receptor activation.
For clearance planning, the general rule is that a drug is effectively eliminated after 5 half-lives. Semaglutide takes approximately 35 days (5 x 7 days) to fully clear after your last dose. Ipamorelin clears in about 10 hours. This matters when transitioning between protocols, managing side effects, or preparing for anti-doping testing.
What factors change a peptide's actual half-life in your body?
Published half-life values represent averages from clinical studies, but individual variation can shift these numbers by 20 to 40% in either direction.
Kidney function is the biggest variable. Most peptides are renally cleared, meaning reduced kidney function extends half-life. A person with mild kidney impairment (eGFR 60 to 89) may see peptide half-lives extended by 15 to 25%. The semaglutide prescribing information notes that renal impairment increases exposure by up to 28% (Novo Nordisk, Wegovy prescribing information, 2021).
Body composition matters too. Peptides distribute through body water, and higher body fat percentages can alter distribution volumes. A 2019 pharmacokinetic analysis by Overgaard et al. (Clinical Pharmacokinetics) found that body weight accounted for 25% of the variability in semaglutide clearance rates.
Injection site affects absorption rate, which indirectly influences effective half-life. Abdominal subcutaneous injections typically show faster absorption than thigh or upper arm sites. For short half-life peptides, this difference is minimal. For longer-acting compounds, it can shift peak concentrations by 1 to 2 hours.
Age and sex also play roles. Women generally show 10 to 15% longer half-lives for GH-releasing peptides compared to men, likely due to estrogen's effects on GH receptor dynamics (Veldhuis et al., Journal of Clinical Endocrinology and Metabolism, 2005). Older adults (65+) may see 15 to 30% longer clearance times due to reduced renal function and altered body composition.
How do modifications extend peptide half-lives?
Native peptides are fragile molecules. The body's enzymes (particularly dipeptidyl peptidase-4, or DPP-4) break them down within minutes. Drug developers use several strategies to extend peptide half-lives from minutes to days.
Albumin binding is how semaglutide achieves its 7-day half-life. A fatty acid chain attached to the GLP-1 molecule binds reversibly to serum albumin, shielding it from enzymatic degradation and renal clearance. Native GLP-1 has a half-life of 1 to 2 minutes. Semaglutide's acylation extends this by approximately 5,000-fold.
PEGylation attaches polyethylene glycol chains to peptides, increasing their molecular size and reducing renal filtration. CJC-1295 with DAC (drug affinity complex) uses a maleimide linker that binds covalently to albumin after injection, extending the 30-minute half-life of unmodified GRF 1-29 to 5 to 8 days.
Amino acid substitution replaces vulnerable residues with non-natural amino acids that resist enzymatic cleavage. Tesamorelin uses this approach, replacing the alanine at position 2 (where DPP-4 cleaves) with a modified residue, extending its half-life from 10 minutes (native GHRH) to 26 to 38 minutes. Not dramatic, but enough for practical once-daily dosing.
Cyclization connects the ends of a peptide chain into a ring structure, protecting internal bonds from exopeptidases. Bremelanotide (PT-141) uses this strategy, achieving a 2 to 3 hour half-life versus the minutes-long half-life of linear melanocortin peptides.
How to use this chart for dosing decisions
The half-life chart is a starting point, not a prescription. Your prescribing physician should adjust dosing based on your specific response, lab values, and treatment goals. But understanding the numbers helps you ask better questions.
For healing protocols using BPC-157 (4 to 6 hour half-life), twice-daily dosing maintains more consistent tissue levels than once daily. A split dose of 250 mcg morning and 250 mcg evening keeps peptide levels above the therapeutic threshold for approximately 16 out of 24 hours, compared to 8 to 10 hours with a single 500 mcg dose.
For GH-releasing peptide stacks (ipamorelin + CJC-1295 without DAC), the timing should align with natural GH pulse windows. Taking both peptides 30 minutes before bed creates a GH surge that coincides with the first deep sleep cycle, maximizing the physiologic response. The short half-lives (2 hours and 30 minutes respectively) mean the stimulation is brief, mimicking a natural pulse rather than creating sustained elevation.
For GLP-1 receptor agonists, the long half-lives allow dosing flexibility within a 1 to 2 day window. If you normally inject semaglutide on Mondays but forget, taking it on Tuesday has minimal impact on steady-state levels. This forgiveness factor is one reason weekly injections show better adherence than daily regimens in clinical practice.
Frequently asked questions
What's the half-life of BPC-157?
BPC-157's half-life hasn't been established through formal human pharmacokinetic studies. Based on its molecular weight (1,419 Da) and rodent data, the estimated half-life is 4 to 6 hours. This supports the common practice of once or twice daily dosing. The peptide is stable in gastric acid, which makes oral administration viable with slower absorption but similar total bioavailability estimates of 20 to 40%.
Why does semaglutide last so much longer than natural GLP-1?
Natural GLP-1 has a half-life of just 1 to 2 minutes because DPP-4 enzymes rapidly cleave it. Semaglutide uses three modifications to resist this breakdown: an amino acid substitution at position 8 (Aib instead of alanine) that blocks DPP-4 cleavage, an acylated fatty acid chain at position 26 that binds to serum albumin (reducing renal clearance), and overall enhanced structural stability. These changes extend the half-life to approximately 168 hours.
Does a longer half-life mean a peptide works better?
Not necessarily. Half-life and efficacy are different properties. Some applications benefit from short, pulsatile exposure (like GH secretagogues mimicking natural GH pulses), while others need sustained levels (like GLP-1 agonists for appetite suppression). A 30-minute sermorelin pulse before bed can be more effective for GH stimulation than a week-long CJC-1295 with DAC exposure, because it better matches the body's natural signaling pattern.
How long do peptides stay detectable in drug tests?
Detection windows extend beyond pharmacological half-life. WADA-accredited labs can detect GH secretagogues for 24 to 72 hours after the last dose using urine testing, and longer through blood markers like IGF-1 elevation. Semaglutide (not currently banned) would remain detectable for 4 to 5 weeks after the last dose due to its long half-life. Detection technology continues to improve, so conservative clearance estimates are always safer.
Does injection site change a peptide's half-life?
Injection site affects absorption rate more than true half-life. Abdominal subcutaneous injections are absorbed fastest due to higher blood flow in that region. Thigh injections are slower, and upper arm falls in between. For short half-life peptides, the difference is minimal (5 to 15 minutes). For longer-acting peptides like semaglutide, absorption differences can shift peak concentration timing by 1 to 2 hours but don't significantly alter the overall 7-day half-life.
Can you extend a peptide's half-life at home?
No. The molecular modifications that extend peptide half-lives (acylation, PEGylation, amino acid substitution) are done during manufacturing. You can't modify a short half-life peptide after purchase. What you can do is optimize timing: dosing short half-life peptides at strategic intervals (before bed for GH secretagogues, near injury sites for BPC-157) maximizes their effect during the brief window they're active.
Medical references
- Wilding JPH, et al. "Once-weekly semaglutide in adults with overweight or obesity." New England Journal of Medicine. 2021;384(11):989-1002.
- Novo Nordisk. "Wegovy (semaglutide) prescribing information." 2021. FDA reference.
- Overgaard RV, et al. "Clinical pharmacokinetics of oral semaglutide." Clinical Pharmacokinetics. 2019;58(10):1353-1363.
- Veldhuis JD, et al. "Estrogen and testosterone modulate GH-releasing peptide stimulated GH release." Journal of Clinical Endocrinology and Metabolism. 2005;90(11):6103-6111.
- Sikiric P, et al. "Stable gastric pentadecapeptide BPC 157." Current Pharmaceutical Design. 2018;24(18):2030-2049.
- Teichman SL, et al. "Prolonged stimulation of growth hormone release by CJC-1295." Journal of Clinical Endocrinology and Metabolism. 2006;91(3):799-805.
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Get startedDisclaimer: This article is for informational purposes only and doesn't constitute medical advice. Half-life values listed here are estimates based on available pharmacokinetic data and may vary between individuals. Most peptides discussed aren't FDA-approved for the applications described. Always consult with a licensed healthcare provider before beginning any peptide therapy. Individual results vary. FormBlends provides semaglutide and tirzepatide through its licensed telehealth platform.