The claim about the freezer being bad is not true. Powder that has not been mixed can go in the freezer, the fridge, or even a cool basement. I have never stacked myself, only read about it. If it were me I would drop the tirz by a milligram first and bring reta in gradually, maybe on the off days so the appetite control overlaps. There are more threads here if you search the site.
Been on 15 mg tirz steadily and now want to layer in reta. What starting amount makes sense? Should the shots happen on the same day or different ones? I figure they stay in separate syringes, right? One more thing: does reta have to stay refrigerated, or is the freezer actually okay? I saw something saying the freezer harms it.