PeptideCalculations
Guide

Peptide Cycle Length: How Long to Run BPC-157, TB-500, GH Secretagogues and GLP-1s

Why GLP-1s run continuously by label, why GH secretagogues get breaks (the hexarelin data), and why BPC-157 and TB-500 cycle lengths are convention only.

By the Peptide Calculations editors · Updated 2026-10-19

“How long do I run it” has three different answers depending on the peptide, and they come from three different kinds of evidence. GLP-1 drugs have FDA labels that say run continuously. GH secretagogues have small human studies showing the response fades with constant use, which is where the idea of a break comes from. Healing peptides like BPC-157 and TB-500 have no human trial at all, so every cycle length you see for them is a community convention. This guide sorts the common peptides into those three buckets and says which is which. Not medical advice; the only numbers here with a clinician behind them are the label ones.

Why cycles exist at all

A cycle is a planned run of dosing followed by a planned break. There are three reasons people build one.

The receptor adapts. Growth hormone releasing peptides (hexarelin, GHRP-2, GHRP-6, ipamorelin) act on the ghrelin receptor, and repeated stimulation blunts the response. The clearest human data is Rahim, O’Neill and Shalet in the Journal of Clinical Endocrinology and Metabolism, 1998: twice-daily subcutaneous hexarelin at 1.5 mcg/kg for 16 weeks. The GH area under the curve fell from 19.1 at baseline to 13.1 at week one, 12.3 at week four, and 10.5 mcg/L per hour at week 16, a drop of roughly 45 percent. Four weeks after stopping it was back to 19.4, not different from baseline. The authors called it a partial and reversible attenuation. Most of the loss happened in the first week and the rest drifted down slowly, so a break resets it but constant use never fully kills it.

The label says to. No peptide label in this site’s tables tells you to cycle. The GLP-1 labels tell you the opposite.

There is no long-term data. For BPC-157 and TB-500 the break is a hedge against the unknown rather than a response to any measured adaptation.

GLP-1s: continuous by label

The Wegovy label escalates semaglutide over 16 weeks (0.25, 0.5, 1, 1.7 mg, four weeks each) and then holds 2.4 mg once weekly as the maintenance dose. There is no stop point; the label’s weight-reduction trials ran 68 weeks. The Ozempic label does the same at diabetes doses (0.25 mg for four weeks, then 0.5 mg, with increases to 1 and 2 mg after at least four weeks on each). The Zepbound label for tirzepatide starts at 2.5 mg for four weeks, then 5 mg, then optional 2.5 mg steps after at least four weeks each, to a maintenance dose of 5, 10 or 15 mg; the trials ran 72 weeks with at least 52 on maintenance.

Retatrutide and cagrilintide are not approved, so there is no label, only trial duration. The phase 2 retatrutide trial in NEJM (Jastreboff 2023) ran 48 weeks of once-weekly dosing with a 4-week safety follow-up. The phase 2 cagrilintide trial in The Lancet (Lau 2021) ran 26 weeks of once-weekly dosing with a 6-week untreated follow-up. Neither tested a cycle. The retatrutide authors noted weight had not plateaued at 48 weeks, which argues that the trial length, not any biological limit, set the end point.

Stopping a GLP-1 is a decision about weight regain, not receptor fatigue. The one dosing rule the Wegovy label does attach to a gap: miss two or more consecutive doses and you restart escalation at a lower dose, because tolerance to the GI side effects is lost.

Healing peptides and GH secretagogues: thin human data

BPC-157 is the clearest case. The 2025 systematic review by Vasireddi and colleagues in HSS Journal screened the orthopaedic and sports medicine literature and found 36 studies: 35 preclinical animal studies and one uncontrolled human chart review. No randomized controlled human trial exists. So the 4 to 8 week cycle you see everywhere is a convention. A widely shared Reddit cheat sheet lists 4 to 8 weeks on and 2 to 4 weeks off at 200 to 500 mcg a day; a Huberman Lab summary describes 8 weeks on and 8 to 10 weeks off.

TB-500 is the same story with a twist. The human trials of thymosin beta-4 (RegeneRx, NCT00832091 and NCT00382174) tested a topical gel on venous stasis and pressure ulcers at three dose levels, and the pressure ulcer trial showed no significant difference from placebo. No human trial has injected it. The injected protocol repeated across community write-ups (for example the Wolverine Stack guide on Substack) is 2 to 2.5 mg twice a week for 4 to 6 weeks as a loading phase, then a lower maintenance dose; other pages describe daily 500 mcg dosing over 8 to 12 weeks instead, so the convention is not even consistent.

GH secretagogues have a little more. Ipamorelin’s only human trial (Beck 2014, Int J Colorectal Dis; NCT00672074) gave 0.03 mg/kg intravenously twice a day for up to seven days after bowel surgery. It says nothing about weeks of subcutaneous use. CJC-1295 with DAC was studied by Teichman 2006 in JCEM in single and multiple ascending doses: GH rose two to ten fold for six days or more and IGF-1 one and a half to three fold for nine to eleven days after one injection, with a half-life of 5.8 to 8.1 days and evidence of a cumulative effect with repeat doses. The 8 to 12 week runs followed by a break that appear on protocol pages such as peptide-db’s CJC/ipamorelin entry are community convention informed by the hexarelin data above. Tesamorelin (Egrifta) is the one GHRH analog with a label, and it is dosed once daily continuously with a note to reconsider continuation if visceral fat has not fallen; there is no cycle in the label.

Cycle length by class

Peptide Run length Break Basis
Semaglutide (Wegovy, Ozempic) continuous; 16-week escalation then maintenance; trials 68 weeks none FDA label
Tirzepatide (Zepbound) continuous; escalation up to 20 weeks then maintenance; trials 72 weeks none FDA label
Retatrutide 48 weeks once weekly in phase 2 none tested trial (Jastreboff 2023, NEJM)
Cagrilintide 26 weeks once weekly in phase 2 6-week untreated follow-up was observation, not a planned break trial (Lau 2021, Lancet)
Tesamorelin (Egrifta) once daily, continuous, reassess if no fat loss none FDA label
Hexarelin 16 weeks twice daily in the one chronic study; GH response down 45% 4 weeks restored baseline trial (Rahim 1998, JCEM)
Ipamorelin 7 days IV in the only human trial; 8 to 12 weeks on protocol pages 4 weeks commonly reported trial for the week, community for the months
CJC-1295 DAC single and repeat doses in Teichman 2006; 8 to 12 weeks on protocol pages commonly reported trial for PK, community for cycle
BPC-157 4 to 8 weeks at 200 to 500 mcg a day 2 to 4 weeks commonly reported; no human RCT (Vasireddi 2025)
TB-500 4 to 6 week loading at 2 to 2.5 mg twice a week, then maintenance varies by write-up commonly reported; human trials were topical gel only

Reading the table: the first five rows have a label or a peer-reviewed trial behind the run length. The hexarelin row is the only direct human measurement of a secretagogue fading with use. Everything below it is convention. When a page gives you a cycle length without saying which of these it is, assume the bottom of the table. For the dose inside the cycle, each peptide’s dosage page lists the range and its basis, and the calculator turns it into syringe units.

Sources

Questions

How long should a BPC-157 cycle be?

There is no human trial to answer that. A 2025 systematic review in HSS Journal found 35 animal studies and one uncontrolled human chart review. Community write-ups cluster around 4 to 8 weeks on and 2 to 4 weeks off, and that is the only basis for those numbers.

Do you cycle semaglutide or tirzepatide?

No. The Wegovy and Zepbound labels describe continuous once-weekly dosing: a 16 to 20 week escalation, then a maintenance dose held indefinitely. The weight-reduction trials behind the labels ran 68 and 72 weeks without breaks.

Do GH secretagogues stop working if you take them every day?

Partly, for some of them. Rahim 1998 gave hexarelin twice daily for 16 weeks and the GH response fell about 45 percent, then recovered to baseline four weeks after stopping. That reversible attenuation is the reason people build breaks into GHRP cycles.

How long does a TB-500 cycle run?

Community write-ups describe a 4 to 6 week loading phase at 2 to 2.5 mg twice a week, then a lower maintenance dose. The only human thymosin beta-4 trials used a topical gel for ulcers, so none of the injected schedule comes from a trial.

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