Switching from one GLP-1 to another

A switch is a prescriber's decision, and the details depend on why you are switching and where you are in the schedule. What follows is the shape of how it usually goes, so the conversation is shorter.

The common switches

Semaglutide to tirzepatide. The most frequent one, usually for more weight loss or less nausea. There is no milligram conversion between the two drugs. Prescribers most often start tirzepatide at 2.5 mg or 5 mg regardless of the semaglutide dose, and some skip the 2.5 mg step for people already tolerating full-dose semaglutide. The last semaglutide shot is still active for about five weeks, so the first tirzepatide weeks overlap with it.

Tirzepatide to semaglutide. Less common, usually driven by coverage or supply. Same principle: a fresh start on the semaglutide ladder, often at 0.5 mg or 1 mg rather than 0.25 mg if tolerance is established.

Injection to pill. The Wegovy pill is 25 mg of oral semaglutide at maintenance, taken on an empty stomach with a small sip of water and a 30 minute wait before eating. Its titration starts at 1.5 mg daily. Foundayo (orforglipron) starts at 0.8 mg daily and has no food or water rules. Neither pill dose maps onto an injection dose, so the pill ladder starts from the bottom or wherever the prescriber chooses.

Ozempic to Wegovy, or Mounjaro to Zepbound. Same molecule, different label and sometimes different pen. These are usually a straight continuation at the same dose, with the next shot on the usual day.

What to ask your prescriber

• Do I take the last dose of the old drug on schedule, then start the new one a week later, or is there a gap?
• What dose does the new drug start at, and how long is each step?
• If side effects on the new drug are worse, what is the plan: hold, step back, or go back to the old one?
• Does my coverage or self-pay price change, and when?

What to log through the change

Log the last old dose and the first new dose as what they are, in the same timeline. In Peptide AI they are two compounds, so the chart shows where one line ends and the other begins. Then log side effects for the first four weeks on the new drug as if it were month one, because for your gut it is. The weight line across the switch is the thing your prescriber will want to see at the next review.

Compounded to brand, and the other way

Moving from a compounded vial to a branded pen at the same milligram dose is usually a continuation. The difference is practical: the vial needs the reconstitution maths and a syringe, the pen does not. If you are moving to compounded, the app's calculator converts the prescribed milligrams to units on the syringe, and the vial row keeps count of what is left.

Logging on Peptide AI is free, and that includes GLP-1s. The dose log, the titration schedule, vials with doses remaining, injection sites with a rotation reminder, nutrition, supplements and training are all on the free tier with no card. Premium adds bloodwork, Oura, WHOOP, Garmin, Apple Health and Health Connect on the same timeline, the body scanner and Remi, the coach that answers from your own log. The pricing page has the three plans.