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A question on split dose protocol timing

17 replies14 peopleSep 22, 2026☆ Follow
Summary

What split-dose schedules for retatrutide minimize side effects like drowsiness while keeping levels stable?

Forum users describe personal split protocols such as Monday/Thursday, Sunday/Thursday, or Friday/Tuesday at roughly equal intervals, with total weekly doses divided in half and given every 84 hours or so. Most report that timing is flexible and that splitting reduces sides and appetite swings compared with single weekly shots. A few alternate retatrutide with tirzepatide or add one to the other, treating the two as independent; others note fatigue may stem from calorie deficit rather than the drug itself.

What this discussion establishesWhere people disagree

Whether alternating retatrutide and tirzepatide prevents either from reaching steady state, or whether simply adding one alongside the other is preferable.

Still open

How much drowsiness on the second injection day is typical and whether it reliably disappears with time or dose adjustment.

Nothing here is advice.

17 replies · 14 people
GreyWillow57archiveopening postSep 22

I'm aiming to raise my rat's dose so the injection day itself feels milder. For anyone who has tried splitting doses, what schedule do you use? My current idea is Friday at 6 pm and Tuesday at 6 am so the hours across the week stay equal and the concentration stays steadier. The rat tends to feel sleepy after the Friday shot, though, so I wonder if the Tuesday one will cause daytime tiredness too. Any experiences or earlier observations to pass along?

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AmberMeadow80archiveSep 22

Tuesdays and Saturdays, 2 mg each time. The exact hour does not appear to make a difference.

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PlainAlder11archiveSep 22

Where did you get the rat, and did you give it a name?

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SteadySparrow75archiveSep 22

5 mg reta Thursday night and 5 mg tirz Monday morning.

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AmberCinder18archiveSep 22
↳ replying to @SteadySparrow75

Wouldn't that keep either compound from settling into any steady level? Splitting tirz alone smooths the peaks and valleys, but switching between two different meds each time seems like it might leave both fluctuating.

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SteadySparrow75archiveSep 22
↳ replying to @AmberCinder18

For me the tirz works at 5 mg and the reta works at 5 mg.

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SlowAlder89archiveSep 22
↳ replying to @GreyWillow57 (opening post)

I've been splitting for nearly five months. Always Monday and Thursday right after work. It has worked well for cutting down sides and keeping hunger under control.

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AmberCinder18archiveSep 22
↳ replying to @SteadySparrow75

I also wonder about simply adding tirz on top of reta on the same days instead of staggering them, whatever the split happens to be.

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LevelThistle44archiveSep 22
↳ replying to @AmberCinder18

Both compounds still reach steady state the same way a single weekly dose would. I inject Monday nights and Friday mornings, though the precise hour has not been critical for me. I've been splitting since December and have lost 90 lb that way.

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NorthWillow72archiveSep 22
↳ replying to @LevelThistle44

I looked around for actual numbers on how much GLP-1, GIP, and glucagon activity comes per milligram of reta versus how much GLP-1 and GIP per milligram of tirz. It would be like splitting the GLP-1 and GIP doses while getting only one glucagon dose a week. I am also curious whether adding straight glucagon to tirz would give similar effects. Just idle curiosity, but I would like to see the data. This is what a quick search turned up.

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LevelWillow41archiveSep 22

Take the weekly amount you want, cut it in half, and inject every 84 hours.

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IronLantern24archiveSep 23

I inject 3.5 mg of reta Sunday night around midnight and another 3.5 mg Thursday morning at 9:30. I have kept to that pattern for four months with no problems.

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RustKettle26archiveSep 23

4 mg Sunday and 4 mg Thursday, both in the morning because that fits my routine better. It has been working well.

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SteadySparrow75archiveSep 23

I treat my reta and tirz as two separate things. I had been on 5 mg tirz twice a week, then replaced one of those weekly shots with reta. My tirz day is Monday morning and reta is Thursday night. I started reta at 2 mg to check for bad sides, then raised it while adjusting the tirz up to 6 mg to keep the total effect similar. The 6 mg tirz brought more reflux, headache, and food aversion than I wanted, so I dropped back to 5 mg. Reta went from 2 mg to 3 mg to 4 mg without issue, though hunger was higher than on tirz. At 5 mg reta I noticed more stomach sounds, burping, a mild headache, and a throat sensation short of reflux, but food-noise control matched the 5 mg tirz and felt about right.

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GreenPebble13archiveSep 23

I'm returning to split dosing this week: 1.5 mg reta Monday morning and 1 mg reta Thursday morning. The only reason I stopped splitting before was the extra pinning. I have run cycles of the Wolverine stack that require daily shots, so I have gotten used to the idea that daily pinning is not that bad.

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QuietAnchor73archiveSep 23
↳ replying to @GreyWillow57 (opening post)

How long have you been on reta? When I first started I felt drowsy a day or two after the shot, but that went away after about a month.

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AmberTimber37archiveSep 23

I do 3.5 mg reta Monday night and 3.5 mg Friday morning. That is about as even as I can manage without shifting the days.

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QuietAnchor73archiveSep 23
↳ replying to @QuietAnchor73

Fatigue, lethargy, and feeling cold can also be signs the body is reacting to a big calorie drop and thinks it is starving. Increasing protein intake often helps ease those feelings.

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