Ask which weight loss injection is best and most articles decline to answer. There is a legitimate reason for the hedging: the right choice depends on your medical history, what your plan will actually pay for, and what your gut will tolerate. But there is more of an answer available now than there was two years ago, because the two leading drugs were finally tested head to head.
Here is what that trial found, what the other outcome trials found, what these medications cost in Houston as of July 2026, and who should not take them at all.
The one trial that compared them directly
Until 2025, every semaglutide-versus-tirzepatide comparison was indirect — setting one trial's placebo-controlled result beside another's, which is a weak way to compare two drugs. SURMOUNT-5 ended that. It randomized 751 adults with obesity and no type 2 diabetes to the maximum tolerated dose of one drug or the other for 72 weeks.
| Outcome at 72 weeks | Tirzepatide (Zepbound®) | Semaglutide (Wegovy®) |
|---|---|---|
| Mean weight change | −20.2% | −13.7% |
| Waist circumference change | −18.4 cm | −13.0 cm |
| Discontinued for GI side effects | 2.7% | 5.6% |
| Serious adverse events | 4.8% | 3.5% |
Tirzepatide produced roughly 47% more mean weight loss. That is not a rounding difference.
Three caveats belong with that number and are usually left out. The trial was funded by the manufacturer of tirzepatide. It was open-label, so participants knew which drug they were on. And 13.7% — the losing result — still exceeds what any non-surgical intervention achieved before this drug class existed.
One more finding worth knowing if you are a man: weight loss ran roughly 6 percentage points lower in men than women, in both arms.
What each drug is approved for, which matters more than efficacy
Efficacy determines what a drug can do. The FDA-approved indication determines whether anyone will pay for it. Those are different questions with different answers.
| Brand | Molecule | Dosing | FDA-approved for | Trial weight loss |
|---|---|---|---|---|
| Wegovy® | Semaglutide | Weekly | Chronic weight management; cardiovascular risk reduction with established CVD; MASH (accelerated approval, Aug 2025) | ~15% (STEP 1) |
| Zepbound® | Tirzepatide | Weekly | Chronic weight management; moderate-to-severe obstructive sleep apnea with obesity | ~15–21%, dose-dependent (SURMOUNT-1) |
| Saxenda® | Liraglutide | Daily | Chronic weight management | ~8% (SCALE) |
| Mounjaro® | Tirzepatide | Weekly | Type 2 diabetes only | Not indicated for weight loss |
| Ozempic® | Semaglutide | Weekly | Type 2 diabetes; CV risk reduction in T2D; CKD in T2D | Not indicated for weight loss |
The Mounjaro/Zepbound and Ozempic/Wegovy pairs cause endless confusion. Each pair is the same molecule with a different label, a different dose ceiling, and a different coverage pathway. Which one you get prescribed is usually a coverage decision, not a pharmacologic one.
The outcome data that should actually drive the choice
If excess weight is your only condition, choose on weight loss and tolerability. Most patients have more than one condition, and then the decision should follow the outcome trials rather than the weight-loss percentage.
Established cardiovascular disease. SELECT randomized more than 17,000 adults with overweight or obesity and established cardiovascular disease but no diabetes. Semaglutide cut major adverse cardiovascular events by about 20%. That is the evidence behind Wegovy's cardiovascular indication, and it is a real reason to choose semaglutide despite the weight-loss gap.
Chronic kidney disease with type 2 diabetes. FLOW was stopped early for efficacy. Semaglutide reduced major kidney events — kidney failure, sustained major loss of kidney function, or death from kidney or cardiovascular causes — by 24%. For a patient with diabetes, obesity, and a falling eGFR, this is the most important number in the class, and it is not a weight number.
Obstructive sleep apnea. SURMOUNT-OSA showed tirzepatide substantially reduced apnea-hypopnea index in adults with moderate-to-severe OSA and obesity. It carries the indication.
Fatty liver disease. ESSENCE supported semaglutide's accelerated approval for metabolic dysfunction-associated steatohepatitis in August 2025.
Read together: tirzepatide wins on weight; semaglutide currently carries the broader set of hard-outcome indications. Anyone who tells you only the first half of that is not giving you the whole picture.
What these cost in Houston, as of July 2026
Cost guidance in this category goes stale faster than almost any other medical topic. Every figure below is current to July 2026 and should be re-verified before you commit to anything.
Three things recently changed the picture.
Medicare. The Medicare GLP-1 Bridge went live July 1, 2026. It is a temporary national demonstration running through December 31, 2027, and it sets a flat $50 monthly copay for eligible Part D beneficiaries on covered weight-loss GLP-1s. It requires enrollment in a standalone Part D plan or a Medicare Advantage plan with drug coverage, plus prior-authorization criteria assessed as of when therapy was first started. CMS has described the Bridge as groundwork for a longer-term program beginning in 2027.
This is a genuine break with the past. Medicare Part D was statutorily barred from covering drugs used solely for weight loss. If a Medicare plan told you in 2024 or 2025 that these were not covered, that answer may now be out of date.
Commercial insurance. Still highly variable and mostly driven by your employer's plan design. Many Texas employer plans exclude anti-obesity medications outright while covering the identical molecule for diabetes. Ask for the formulary status of Wegovy and Zepbound by name — not whether "GLP-1s" are covered.
Cash pay. Manufacturer direct-to-consumer channels and the federal TrumpRx site now list negotiated cash prices well below the historical list prices above $1,000 per month. Prices vary by drug, formulation, and dose, and starter doses price lower than maintenance doses. That distinction matters, because nearly everyone ends up on a maintenance dose.
Texas Medicaid. State participation in obesity GLP-1 coverage is optional and differs by state. Confirm current Texas status directly rather than assuming either way.
Why compounded semaglutide and tirzepatide largely disappeared
For roughly three years a large secondary market sold compounded semaglutide and tirzepatide for a few hundred dollars a month. That market existed because of one specific legal provision: compounders may produce copies of an FDA-approved drug while that drug sits on the FDA shortage list.
Both shortages ended. The FDA declared the tirzepatide shortage resolved in December 2024 and semaglutide in February 2025, then set wind-down deadlines through 2025. Compounders and outsourcing facilities challenged the timeline in federal court and lost. On April 30, 2026, the FDA went further, proposing to remove semaglutide, tirzepatide, and liraglutide from the list of bulk substances outsourcing facilities may compound from, having found no clinical need.
Practically: mass-market compounded GLP-1s are no longer a lawful supply channel. Patient-specific compounding for a documented clinical need — a genuine allergy to an inactive ingredient, say — remains legal, but that is a narrow exception and it is not what the large online sellers were doing.
The rationale was not only commercial. By early 2025 the FDA had logged hundreds of adverse event reports tied to compounded versions, a large share involving patients drawing the wrong dose from multi-dose vials, some requiring hospitalization.
If a clinic is still advertising compounded semaglutide or tirzepatide at a low monthly price, ask what legal basis it is operating under. That is a fair question and it should have a clean answer.
Side effects, and one that matters more in a Houston summer
Most side effects are gastrointestinal — nausea, vomiting, diarrhea, constipation, reflux — and they cluster during dose escalation rather than at steady state. The profiles differ. Semaglutide skews toward nausea and constipation; tirzepatide toward diarrhea. In the head-to-head trial, GI effects drove more discontinuation on semaglutide.
There is a local wrinkle that national coverage never mentions.
These drugs blunt appetite and fluid intake, and their GI effects cause fluid loss. A Houston summer adds sweat losses on top of that, and a large share of this region's workforce spends the day outdoors. Volume depletion is the main mechanism behind reported acute kidney injury on GLP-1 therapy. If you are escalating your dose in July, working outside, or both, deliberate fluid intake is not optional — and checking a kidney function panel during escalation is a reasonable precaution rather than an excessive one.
Do not take these if you are pregnant or trying to conceive. Both carry a boxed warning against use with a personal or family history of medullary thyroid carcinoma or MEN2. Use caution with a history of pancreatitis, gastroparesis, or active diabetic retinopathy. And tell any surgeon or anesthesiologist you are on one, because delayed gastric emptying changes fasting instructions before a procedure.
What happens when you stop
Most people ask this last. It should be asked first.
When semaglutide was withdrawn in the STEP 1 extension, participants regained about two-thirds of the weight they had lost within a year. SURMOUNT-4 found the same pattern with tirzepatide: continued treatment held the loss, withdrawal reversed much of it.
That is not a failure of the drug. It is what treating a chronic disease looks like — the same thing happens when you stop a blood pressure medication. But it means the honest framing is ongoing therapy, not a course of treatment, and any plan built around stopping at a goal weight should say plainly what is likely to follow.
Who qualifies
FDA labeling for chronic weight management covers adults with a BMI of 30 or higher, or 27 or higher with at least one weight-related condition — type 2 diabetes, hypertension, dyslipidemia, obstructive sleep apnea, or cardiovascular disease.
BMI is a crude screen that misclassifies people at both ends. It overstates adiposity in muscular patients and understates it in older adults who have lost muscle mass. It is what insurers use, so it is what determines coverage. It should not be the only thing your physician looks at.
What a real evaluation includes
Before a prescription: a full history including every medication that may be driving weight gain, thyroid function, A1c or fasting glucose, a lipid panel, liver enzymes, and kidney function with a urine albumin-to-creatinine ratio if you have diabetes or hypertension. A screen for sleep apnea if there is snoring or daytime sleepiness. An explicit review of contraindications. A dose-escalation plan with stated intervals.
After: follow-up scheduled during escalation, not only at twelve weeks. Repeat labs. Attention to protein intake and muscle mass, because a meaningful share of the weight lost on these drugs is lean tissue. And a plan for what happens once you reach the maintenance dose.
If a service will prescribe these off a web form with no labs and no follow-up, that is not medical weight management. It is a fulfillment channel.