Every dosage page in this market ends up at the same question, and almost none of them answer it from a source. The dose is stated, the frequency is stated, and then a line appears: 4 to 6 weeks, followed by a 2 to 4 week break.
This site has now published dosage references for more than thirty compounds, opening the primary record for each one. This page reports what that record contains about duration, which is less than the guides imply and more interesting than nothing.
The census
On 19 September 2026 we queried ClinicalTrials.gov for fourteen compounds sold through this market and read the title of every registration returned.
| Compound | Registrations | Titles containing "cycle" |
|---|---|---|
| kisspeptin | 45 | 1 |
| sermorelin | 42 | 0 |
| tesamorelin | 24 | 0 |
| selank | 10 | 0 |
| MOTS-c | 8 | 0 |
| BPC-157 | 4 | 0 |
| ipamorelin | 3 | 0 |
| GHK-Cu | 2 | 0 |
| TB-500 | 1 | 0 |
| CJC-1295 | 1 | 0 |
| melanotan | 1 | 0 |
| epitalon, semax, adipotide | 0 | 0 |
| Total | 141 | 1 |
The single hit is NCT03018314, Serum Kisspeptin Levels in Infertile Women, where "cycle" means the menstrual cycle.
The word is likewise absent from the current PITOCIN label, a document that specifies oxytocin dosing down to millilitres per hour. It is a term of art in one community and not in the other, and the query is reproducible in a few minutes by anyone who wants to check it.
Two of those counts deserve a footnote. Epitalon and semax return zero because they have no registrations at all — a fact this site has documented separately. Adipotide returns zero because its one trial is filed under the development name Prohibitin Targeting Peptide 1, which is the registry-naming trap that page covers.
The one real "cycle", and what it means there
That adipotide trial is the exception that clarifies the rule. Its full title is A First-in-Man, Phase I Evaluation of A Single Cycle of Prohibitin Targeting Peptide 1 in Patients With Metastatic Prostate Cancer and Obesity.
"Cycle" there is oncology vocabulary. It means one defined course of treatment — in that protocol, 0.03 mg/kg daily for 28 days — administered once. There is no off period, no repetition, and no recovery rationale. The word describes the shape of a single course, which is close to the opposite of the on-and-off pattern the research market means by it.
So the one place the term appears in the human record for these compounds is a place where it means something else.
What the human record specifies instead
Duration is specified constantly. It is simply never specified as a cycle.
| Source | Duration stated | What sets it |
|---|---|---|
| NOVAREL (hCG) label | 3 weeks; 4–6 weeks; 6 weeks; 6–9 months then 3 months | The indication being treated |
| Pivotal tesamorelin trial (Falutz et al., 2010) | 2 mg daily for 6 months, n=404 | The trial's measurement window |
| Adipotide, monkey and human | 28 days, both species | The study's dosing period |
| PITOCIN label | Minutes to hours, titrated | An observed uterine response |
| The semaglutide dose ladders, tirzepatide labels | 4-week intervals | Titration steps toward maintenance; then chronic use with no stop date |
Three different logics are visible there, and none is a cycle. An indication sets a course. A trial sets a window. A titration sets an interval before the next increase. The GLP-1 labels are the clearest case: they use the four-week unit that cycle guides also use, and they use it to move up, indefinitely, with no off period anywhere in the document.
What the guides state, and what the same guides also say
The figures in circulation are real, published, and attributable. This site opened them while writing its compound pages.
For BPC-157, the pages we opened state 2 to 6 weeks by goal (a clinic guide), 4 to 6, 6 to 8 or 8 to 12 weeks (a protocol site), and 4 to 12 weeks with a 2 to 4 week break (a vendor-affiliated guide). For GHK-Cu, they state 4 to 8 week cycles, 8 to 12 weeks on with 4 weeks off, and 30-day cycles split into two 15-day phases with a 30-day rest.
The notable thing is not the disagreement. It is that one of those same protocol pages states, in its own text, that there is no published human Phase 2 or Phase 3 dose-finding trial for BPC-157 — on the page where it specifies three alternative cycle lengths. Both sentences are published. Only one of them gets quoted onward.
This is what a convention looks like from the inside: figures that are consistent in shape (a number of weeks on, sometimes a number off), inconsistent in value, and unattached to any measurement.
What a real cycle length would require
The word has a defensible meaning in the context it came from. In anabolic steroid use, administration suppresses the hypothalamic-pituitary-gonadal axis, and the off period exists to allow it to recover. That is a mechanism, with a literature, specific to those compounds.
Transferring the word does not transfer the reasoning. For a peptide to have an evidence-based cycle length, a source would need to establish two things:
- That continued administration produces a declining or adverse effect over time — tolerance, receptor desensitisation, a cumulative toxicity, an antibody response.
- That an interruption of some stated length reverses it.
Receptor desensitisation is the argument usually offered for growth hormone secretagogues, and it is not an unreasonable one. But the sources opened for this catalogue assert it rather than measure it in people over a stated interval, and none of them closes the second half — the length of interruption that would undo it. Establishing part one without part two gives a reason to stop, not a schedule.
For most of this catalogue the question does not arise in the literature at all, because the human file is a handful of short early-phase studies. A compound with four papers and one terminated trial has no duration data to have an opinion about.
What this page is not saying
It is not saying that continuous administration is safe, or that stopping is unnecessary. The absence of evidence for a cycle length is not evidence that none is needed — and several compounds in this catalogue have documented signals that would be more concerning under continued administration, such as the reversible renal changes recorded in the adipotide monkey study at its effective dose.
It is saying that the specific numbers in circulation — four weeks, eight weeks, twelve on and four off — are conventions that no source has tested, that they disagree with each other, and that several of the pages publishing them say as much in their own text. Anyone who wants to check this can: the registry query above takes minutes, and the guides' own disclaimers are on the same pages as their figures.
The broader pattern this belongs to — sourced figures whose provenance is weaker than the confidence with which they are quoted — is set out in how to read a dosing claim, and the per-compound record is indexed on the peptide dosage chart.
Sources
- ClinicalTrials.gov API v2, term queries for fourteen compounds, all returned titles read individually; 141 registrations, one title containing "cycle" (NCT03018314). Read 19 September 2026.
- ClinicalTrials.gov, NCT01262664, identification module. Read 19 September 2026.
- PITOCIN (oxytocin) injection label, Par Health USA, DailyMed set id
6e5a66fc-e507-497c-b5ce-44a8c95898ad, published 21 May 2026, full text searched for the term. Read 19 September 2026. - NOVAREL (chorionic gonadotropin) label, dosage regimens by indication, as recorded on this site's hCG dosage page (read 16 September 2026).
- Falutz J et al., JAIDS 2010, pivotal tesamorelin trial duration, as recorded on this site's tesamorelin and sermorelin page.
- Clinic, protocol and vendor dosage guides for BPC-157 and GHK-Cu, opened and tabulated on this site's pages for those compounds (dated 2025-10-30 to 2026-08-30).