CommunityDosing & Titration

Reta Dosage Question

15 replies11 peopleAug 17, 2026☆ Follow
Summary

What is retatrutide half-life and should dosing be split twice weekly when stacked with tirzepatide?

Users report retatrutide half-life near six days. Some prefer once-weekly injections for steady buildup while others split doses to smooth appetite control and reduce GI sides. Stacking with tirzepatide leads several to choose twice-weekly pins for consistency. Side-effect tolerance often develops over time so waiting before further increases can help.

What this discussion establishesWhere people disagree

Whether once-weekly or twice-weekly produces meaningfully different average exposure or efficacy

Still open

Optimal long-term schedule when combining retatrutide above 4 mg with 15 mg tirzepatide

Nothing here is advice.

15 replies · 11 people
PlainTimber88archiveopening postAug 17

Curious about the half-life for Reta. Anyone willing to share what twice-weekly injections feel like? Appreciate any input. Right now I take 15 mg tirz once a week plus 2 mg reta split across two shots. This probably sounds pretty uninformed, which it is, because the half-life part has me puzzled.

LevelThistle44archiveAug 17
↳ replying to @PlainTimber88 (opening post)

Around six days when split twice weekly. Seems to work fine.

LevelFenwick92archiveAug 17

Half-life sits near six days or about 144 hours. Better to keep it to one shot per week rather than splitting because levels build up gradually toward steady state.

LevelThistle44archiveAug 17
↳ replying to @LevelFenwick92

Buildup still occurs and total exposure stays the same either way.

ClearLantern70archiveAug 17

I inject every six days. Stacking with tirz would probably throw me off so twice a week feels safer.

LevelThistle44archiveAug 17
↳ replying to @ClearLantern70

Makes sense. I split one GLP on Monday and Friday and the other on Wednesday and Saturday.

WarmCompass44archiveAug 17

No real reason to split if 4 mg at once causes no sides. Splitting mainly helps when sides appear. Have you tried the full 4 mg in a single shot yet?

SlowAlder89archiveAug 17

Twice-weekly injections have worked okay since I began. Highs are lower and lows are higher so appetite control stays steadier. Just one person’s experience though.

LevelThistle44archiveAug 17
↳ replying to @WarmCompass44

Steadier blood levels keep hunger more predictable instead of the usual drop-off around days five to seven.

BrightCompass57archiveAug 17
↳ replying to @LevelFenwick92

That claim does not hold up. Once-weekly creates repeated big peaks followed by drops. Twice-weekly also tends to produce fewer sides.

IronLantern24archiveAug 18

Started with every-six-day shots for five months then switched to every 3.5 days because of sides. Effectiveness never dropped after moving to twice weekly.

CopperSignal27archiveAug 18

Splitting mainly cuts sides or lets you tweak the dose faster. Half-life hovers around six days. If you plan to raise the reta amount later, staying twice-weekly makes sense even without current sides. Doses above tirz 15 mg plus reta 4 mg often bring issues so smaller more frequent shots usually soften them. My own weekly total is close to tirz 15 mg, reta 6 mg and cagri 0.5 mg split every other day.

WarmWillow50archiveAug 18

Planning to split my reta now. Tried 4 mg twice already and the sides hit hard with bloating, sulfur burps and stomach upset. Going to test 2 mg on Friday and Tuesday for a while. 3 mg feels fine but 4 mg in one go gets rejected.

CopperSignal27archiveAug 18
↳ replying to @WarmWillow50

That approach fits those side effects well, especially when they only last two or three days. Early fade is strong evidence splitting will help. Another option is simply waiting because GI sides usually show tolerance unlike the weight-loss effects, so retrying the higher dose after one or two months can work. On ozempic I could never pass 0.5 mg and ended up using 0.22 mg every other day to reach 0.8 mg weekly while keeping nausea down.

SteadyQuill58archiveAug 18

Every-five-day schedule has suited me for a couple months. Used to get quite hungry on day five but now the effects feel more even.

WarmWillow50archiveAug 18

Yes the sides usually fade after about three days on 4 mg. Just ordered some pens so the extra injections will be simpler.

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