Peptide Protocol IQ
Cycle directory

How long people run these, and how long anyone actually has

Every compound here carries two durations side by side: the on and off period that circulates in practice, and the longest exposure in a verified human study. Where those two disagree, the disagreement is the point of the row.

Of 18 compounds, 10 have a verified human study to compare against at all, and 5 have any published evidence bearing on cycling or on what happens after stopping. The rest carry conventions with no source, shown as conventions.

Where “8 weeks on, 4 weeks off” came from

Not from a trial. The pattern is imported from anabolic steroid practice, where a break exists to let suppressed endogenous hormone production recover. Most compounds on this page suppress nothing, so the reasoning does not carry over even in principle. That does not make a break harmful. It makes it unevidenced, which is a different claim and the only one this site will make.

Every compound, both durations

“Longest human study” counts only records with a verified identifier. A dash means no human exposure has been published for that compound at all.

CompoundCommonly runBreakLongest human studyBasis for cycling
Semaglutide68 weeksNone68 weeksOn/off studied
Tirzepatide72 weeksNone72 weeksOn/off studied
Retatrutide48 weeksNone48 weeksConvention only
Cagrilintide68 weeksNone68 weeksConvention only
Tesamorelin52 weeksNone52 weeksOn/off studied
BPC-1578 weeks4 weeksNo human exposure publishedConvention only
TB-5006 weeks4 weeks2 weeksConvention only
GHK-Cu6 weeks4 weeks12 weeksMechanistic argument
KPV4 weeks4 weeksNo human exposure publishedConvention only
CJC-129512 weeks4 weeksNo human exposure publishedMechanistic argument
Ipamorelin12 weeks4 weeks1 weekMechanistic argument
MOTS-c4 weeks4 weeksNo human exposure publishedConvention only
Selank2 weeks2 weeksduration not statedOn/off studied
Semax2 weeks3 weeks6 weeksOn/off studied
AOD-960412 weeks4 weeksNo human exposure publishedConvention only
NAD+4 weeks4 weeksNo human exposure publishedConvention only
5-Amino-1MQ8 weeks4 weeksNo human exposure publishedConvention only
Epitalon2 weeks24 weeksNo human exposure publishedConvention only

What each one says about stopping

The question a cycle length is really asking. Search or filter by how well evidenced the answer is.

18 of 18 compounds

Semaglutide

On/off studied

68 weeks on · no break

Why a break: Not conventionally cycled. The approved use is continuous, and the trial that established the effect ran 68 weeks without a break.

On stopping: This is one of the few compounds on the site where discontinuation has been studied rather than guessed. Weight regain after stopping is well documented across the class, and the published extension work found most of the lost weight returned within a year. Treat it as a maintained-effect compound.

Tirzepatide

On/off studied

72 weeks on · no break

Why a break: Not conventionally cycled. The labelled schedule is continuous once the maintenance amount is reached.

On stopping: The randomised withdrawal work in this class shows substantial regain after stopping. The 176-week follow-up describes what continued use looks like, not what stopping looks like.

Retatrutide

Convention only

48 weeks on · no break

Why a break: Not cycled in the trial. The phase 2 ran 48 weeks continuously with a 4-week safety follow-up.

On stopping: Unstudied. The phase 2 followed participants for four weeks after treatment, which is a safety window rather than a durability measurement. Nothing published describes what happens to the weight change after stopping.

Cagrilintide

Convention only

68 weeks on · no break

Why a break: Not cycled. Both the monotherapy dose-finding trial and the phase 3 combination programme ran continuously.

On stopping: Unstudied as a separate question. The mechanism is satiety signalling, which by construction stops when the drug does.

Tesamorelin

On/off studied

52 weeks on · no break

Why a break: The approved use is continuous daily administration, not a cycle.

On stopping: Studied, and the result matters: visceral fat returned toward baseline after discontinuation in the published follow-up. This is a maintained-effect compound and the effect is not banked.

BPC-157

Convention only

8 weeks on · 4 weeks off

Why a break: The eight-on, four-off convention has no source. It appears to have been imported wholesale from anabolic steroid practice, where cycling exists to allow recovery of suppressed endogenous hormone production. BPC-157 suppresses nothing, so the rationale does not transfer even in principle.

On stopping: No human data of any kind. The only registered human trial used oral tablets over two weeks and never posted results.

TB-500

Convention only

6 weeks on · 4 weeks off

Why a break: A loading period followed by maintenance, then a break. The structure is convention; no trial has compared it with continuous use or with nothing.

On stopping: Not studied for this compound. The linked human study used full-length thymosin beta-4 intravenously for ten consecutive days and measured pharmacokinetics, not durability.

GHK-Cu

Mechanistic argument

6 weeks on · 4 weeks off

Why a break: Copper accumulation is the argument usually given for limiting duration. It is a reasonable concern and it has not been quantified for injected use in any published human study.

On stopping: Not studied. The one human randomised trial ran twelve weeks topically and was negative on every objective endpoint, so there was no effect to observe the loss of.

KPV

Convention only

4 weeks on · 4 weeks off

Why a break: There is no rationale to report. The figures in circulation are conventions applied to a compound with no human record.

On stopping: The FDA's compounding advisory briefing states it has identified no clinical studies and no human exposure data for KPV by any route. There is nothing to say about stopping because there is nothing published about starting.

CJC-1295

Mechanistic argument

12 weeks on · 4 weeks off

Why a break: Receptor desensitisation is the argument: sustained secretagogue exposure is expected to blunt the pulse it produces. That is a real pharmacological concern for this class and it has not been measured in a published human trial of this compound.

On stopping: Unstudied. Any effect on the growth hormone axis is expected to reverse, since the mechanism is stimulation rather than replacement.

Ipamorelin

Mechanistic argument

12 weeks on · 4 weeks off

Why a break: Same desensitisation argument as the other secretagogues, and the same absence of a trial testing it.

On stopping: Unstudied. The only human randomised trial ran about a week after surgery, intravenously, and missed its endpoint.

MOTS-c

Convention only

4 weeks on · 4 weeks off

Why a break: No rationale can be reported. The first interventional human study was registered in 2026 and its registry entry does not disclose the amount administered.

On stopping: No human exposure has been published, so nothing is known about stopping.

Selank

On/off studied

2 weeks on · 2 weeks off

Why a break: The Russian literature describes short courses rather than continuous use, so the short on-period here is closer to the published pattern than most conventions on this page.

On stopping: One published trial reports the anxiolytic effect persisting for about a week after the last administration. That is unusually specific for this category and worth noting.

Semax

On/off studied

2 weeks on · 3 weeks off

Why a break: The published stroke work used courses of five to ten days, in one trial repeated after a twenty-day break. Continuous multi-week use is a community extension of that, not a copy of it.

On stopping: Not studied as a separate question.

AOD-9604

Convention only

12 weeks on · 4 weeks off

Why a break: Convention. The sponsor programme ran continuously for up to six months and did not cycle anything.

On stopping: Not a meaningful question here: the human programme did not demonstrate a significant weight effect against placebo at its primary endpoint, and development stopped. There is no effect whose loss could be measured.

NAD+

Convention only

4 weeks on · 4 weeks off

Why a break: Convention. Clinic infusion schedules are built around cost and appointment logistics as much as around anything pharmacological.

On stopping: Blood NAD+ concentration falls when supplementation stops. Whether that matters depends on a downstream clinical benefit that has been inconsistent in the published record.

5-Amino-1MQ

Convention only

8 weeks on · 4 weeks off

Why a break: Convention. There is no published human dosing trial to cycle against.

On stopping: No human exposure data has been published.

Epitalon

Convention only

2 weeks on · 24 weeks off

Why a break: Short courses repeated once or twice a year, following the pattern described in the originating Russian literature.

On stopping: Not characterised in any adequately reported human trial.

Three things a cycle length cannot tell you

That a longer run is safe. Findings from a short study do not extend to a longer one. If the longest published exposure is twelve weeks and the plan is twenty-four, the second half has no evidence behind it, and that is true even if the first half went well.

That the effect persists. For the compounds where discontinuation has actually been measured, it mostly does not. Tesamorelin’s visceral fat reduction reversed. Weight returns after the incretins are stopped. These are the best-evidenced compounds on the site, and they are the ones where stopping undoes the result.

That a break does anything. No trial on this site compared cycled against continuous administration for any compound. The break is a convention, and its main documented effect is on the number of vials required, which the cost model will calculate honestly either way.