ForumDosing & Titration

Adding Reta to Tirz Schedule Question

6 replies4 peopleMay 27, 2026☆ Follow
Summary

How to add retatrutide when already on a high tirzepatide dose for more weight loss

The original poster on 15 mg tirzepatide after an 85 lb loss wants to add reta and continue losing 125-150 lb more while keeping their current diet and training. Replies suggest a full switch to reta may be preferable for the added glucagon effect rather than stacking, though one user shares a low-dose reta plus cagri bridge on top of tirz. Mixed experiences with the tirz-reta combination are noted, including increased side effects for some. Personal titration stories emphasize starting low and using larger vials for convenience.

What this discussion establishesWhere people disagree

Whether to keep tirz while adding reta or drop tirz entirely and move to reta (possibly with cagri)

Still open

Best starting dose and titration speed when switching from 15 mg tirz

Nothing here is advice.

6 replies · 4 people
WryLedger43archiveopening postMay 27

Hi everyone. Thanks in advance for any experiences or thoughts. I'm on 15 mg of Tirz right now after losing 85 lb in the first year. I still want to drop another 125-150 lb. My diet is steady with 200 g of protein daily, lifting three times a week and doing HIIT cardio twice a week. I'm thinking about adding Reta to what I'm already doing. I figure I could start at a higher dose, even though slow titration is the usual advice, because I'd rather buy a stronger strength to cut down on how many times I need to reorder. Appreciate the read and any input.

LevelThistle44archiveMay 27

Plenty of threads this year cover this topic. Given how much you've already lost and how much more you want to lose, Reta looks like the stronger option based on trial results. Adding another peptide like cagri also seems reasonable for the scale of drop you're aiming for. I lost 10 lb on Tirz in the first month, then switched to Reta and dropped another 58 lb over about 24 weeks, not counting a few pounds from creatine. I agree it's worth focusing on the better price per mg, which usually means going with the larger vials.

GreenQuill96archiveMay 27

I wouldn't jump in with a fairly high starting dose of Reta. Adding it on top mostly duplicates the GLP and GIP activity while bringing in some glucagon. For reference, I'm only at 9 mg Tirz on Fridays but on Tuesdays I use a small tide-over of 3.25 reta plus 0.75 cag.

LevelThistle44archiveMay 27
↳ replying to @GreenQuill96

If the goal is another 150 lb, I'd probably switch fully to Reta instead of stacking, assuming it's tolerated. The GCGR signaling should help over the long run, and the target is likely past the usual effective range for Reta anyway, so easing in slowly may not be necessary.

GreenQuill96archiveMay 27
↳ replying to @LevelThistle44

I agree completely that going hard on Reta, maybe with Cag too, means dropping Tirz. I was only talking about mixing if the 15 mg Tirz dose is going to stay in place.

WarmSparrow60archiveMay 27

Look into Eloralintide. It's currently being tested alongside Tirz in trials. The Tirz plus Reta combination has gotten mixed feedback, with some people returning to Tirz alone because of extra side effects from the overlap.

LevelThistle44archiveMay 28

I began with the smaller and larger vial sizes because I wasn't sure how quickly I'd move off Tirz or how dosing would progress on Reta. I'm fine keeping a reconstituted vial in the fridge for up to ten weeks. I used up three of the smaller vials between mid-January and end of March before moving to the first larger one. Looking back, the larger size alone would have worked with a bit of waste, but it didn't really matter. I was only on 5 mg Tirz when I switched. I did lots of small injections so any sides wouldn't last days. I never ran into sides bad enough to slow down, so the switch felt successful on speed, comfort, and results. The tracking app won't show both compounds on one chart and doesn't go back to the start of Reta use, so I ended up with two separate charts.

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