Switching From Wegovy to Zepbound: Is There a Dose Conversion Chart?

There is no official Wegovy-to-Zepbound dose conversion. Zepbound's label starts everyone at 2.5 mg weekly for four weeks, then steps up by 2.5 mg, and says nothing about what you were taking before. Trials have never established equal doses of the two drugs. One study in type 2 diabetes switched people straight to 5 mg.

So any chart you see that pairs a Wegovy dose with a "matching" Zepbound dose is someone's rule of thumb, not a label instruction or a trial result. That doesn't make switching unusual. It just means the decision about where to restart belongs to the prescriber, and the evidence they have to work with is thinner than the charts suggest.

What do the labels actually say?

Zepbound (tirzepatide) starts at 2.5 mg weekly for four weeks. The dose then goes up by 2.5 mg after at least four weeks at each step, to a maintenance dose of 5, 10 or 15 mg; 15 mg is the maximum ¹. The label also says Zepbound should not be combined with any other GLP-1 drug ¹, so the switch is a stop-and-start, not an overlap.

Wegovy (semaglutide) climbs from 0.25 mg through 0.5, 1 and 1.7 mg to a 2.4 mg maintenance dose, with an optional step to 7.2 mg for people who have tolerated 2.4 mg for at least four weeks ². The Wegovy label covers switching between its own injection and its own tablets, with specific timing, but not switching to another company's drug ².

One label detail matters more than it looks. Semaglutide has a half-life of about a week, and the Wegovy label says it stays in the circulation for about five to seven weeks after the last 2.4 mg or 7.2 mg dose ². For the first weeks on Zepbound, you still have semaglutide on board.

Where do people restart? What the studies tested

Only a handful of studies have looked at the switch itself, and all of them were in type 2 diabetes, not weight management.

• •Straight to 5 mg. In a prospective study, adults on a stable GLP-1 drug, including semaglutide at 0.5, 1 or 2 mg, switched directly to tirzepatide 5 mg. Over 12 weeks HbA1c fell another 0.43 points and weight another 2.15 kg; 13.2% had gastrointestinal side effects and 2% stopped tirzepatide because of side effects ³.
• •Restarting at 2.5 mg. A small Japanese study followed 15 people who left semaglutide 1 mg because weight loss had stalled. All restarted tirzepatide at 2.5 mg and moved up to 7.5 or 10 mg; only the 10 mg group showed a significant HbA1c drop over three months ⁴.
• •A model, not a trial. A modeling study simulated switching from semaglutide 0.5 to 2 mg to tirzepatide and predicted further HbA1c and weight reductions, even at the 5 mg maintenance dose ⁵.

None of these tested switching from Wegovy at weight-loss doses, and none tested switching down from 7.2 mg.

Is tirzepatide stronger at matching doses?

At the top of each ladder, yes. In SURMOUNT-5, the head-to-head obesity trial, people on the highest tolerated tirzepatide dose (10 or 15 mg) lost 20.2% of body weight at 72 weeks, versus 13.7% on the highest tolerated semaglutide dose (1.7 or 2.4 mg) ⁶. Gastrointestinal side effects were the most common in both groups and showed up mainly during dose escalation ⁶.

That trial compared maximum doses. It does not tell you what milligram of tirzepatide "equals" a milligram of semaglutide, and nobody has run the trial that would. The two molecules don't even act on the same set of receptors, which is part of why a straight conversion doesn't exist. The semaglutide vs tirzepatide comparison covers how that gap does and doesn't carry down to small doses.

Switching at a microdose

If you are on a compounded, sub-starter dose of semaglutide and moving to compounded tirzepatide, there is no data at all. No study has tested switching between microdoses, and the label rules above describe the brand products only. Microdosing either drug is off-label and unproven.

The practical risk is arithmetic. Compounded vials come in different strengths, so the same number of units on a syringe can mean very different milligram doses after a switch. Work the units out from the new vial's concentration, not the old one, using the tirzepatide presentation calculator or, for pens, the pen click calculator.

What does each step cost?

Brand prices are tiered by dose, so a switch that restarts at 2.5 mg starts at the cheapest Zepbound price. On Lilly's LillyDirect page, read October 2, 2026, self-pay Zepbound costs $299 a month at 2.5 mg, $399 at 5 mg and $449 at 7.5 to 15 mg. The $449 price assumes a refill within 45 days; otherwise Lilly lists $499 for 7.5 mg and $699 for 10, 12.5 and 15 mg. KwikPens and single-dose vials are priced the same ⁷.

On NovoCare, read the same day, Wegovy injections cost $349 a month at any dose from 0.25 to 2.4 mg after a new-patient offer of $199 for the first two fills of 0.25 or 0.5 mg (through December 31, 2026), and $399 for the 7.2 mg dose ⁸.

So moving from Wegovy 2.4 mg to Zepbound 2.5 mg lowers the bill by $50 a month at first and raises it from 5 mg on. Compounded plans usually price differently, often at one flat rate across doses; current plans are compared on the cheapest microdose tirzepatide board.

What to watch for during the switch

The trials that measured it found gastrointestinal effects were the main problem during dose escalation ⁶, and restarting tirzepatide at 5 mg rather than 2.5 mg produced gastrointestinal effects in 13.2% of people over 12 weeks ³. Because semaglutide lingers for weeks, the first month on Zepbound is effectively a period of exposure to both. If nausea or vomiting builds instead of settling, that is worth raising with the prescriber before the next step up, not after.