Zepbound vs Wegovy: Two Drugs, Not Two Brands

Zepbound vs Wegovy is not a choice between two strengths of the same medicine. Zepbound is tirzepatide, made by Eli Lilly. Wegovy is semaglutide, made by Novo Nordisk. Two different molecules from two different companies — so no, Zepbound is not a semaglutide, and moving from one to the other is changing drugs, not changing doses.

Almost everything else follows from that. The two act on a different number of targets, they are cleared to treat different things, one of them now comes as a pill, and they are priced differently.

What is actually inside each one

Both are lab-made copies of a hormone your gut already produces. When you eat, the gut releases signals called incretins — chemical messages that tell the pancreas to release insulin and tell the brain you have had enough.

Wegovy copies one of those signals, GLP-1. Semaglutide is a long-lasting version of it, so instead of fading within minutes it stays active for about a week.

Zepbound copies two. Tirzepatide reaches the GLP-1 target and a second one called GIP, the other main incretin. One molecule, two switches. The two molecules differ both in receptor targets and in peptide sequence and chemical modifications (Zepbound prescribing information, Wegovy prescribing information); if you want it at the molecule level rather than the brand level, tirzepatide vs semaglutide goes there.

Zepbound vs Wegovy: what each one is cleared to treat

Here is where the two brands genuinely part company, and it is the part people rarely check before deciding they want one.

The sleep-apnea line came from two trials called SURMOUNT-OSA, where people on tirzepatide for sleep apnea had roughly 20 to 24 fewer breathing interruptions per hour of sleep than people on placebo after a year (NEJM, 2024). The heart line came from SELECT, which followed 17,604 adults with existing heart disease for about three and a half years: 6.5% of the semaglutide group had a heart attack, stroke or cardiovascular death, against 8.0% on placebo (NEJM, 2023).

As of September 6, 2026, the day this article was written, the newest Zepbound labeling is dated August 2026 and was posted on September 2. It added a caution about temporary worsening of diabetic retinopathy — damage to the small blood vessels at the back of the eye — in people with type 2 diabetes whose blood sugar drops quickly, which the Wegovy labeling already carried. Both labels also dropped their separate section on suicidal behaviour and ideation in February 2026. The two warning lists sit closer together now than they did a year ago.

The trials that put them head to head

A prior trial, SURPASS-2, directly compared tirzepatide with semaglutide 1 mg in adults with type 2 diabetes; SURMOUNT-5 later compared the weight-management doses in adults with obesity but without type 2 diabetes. SURMOUNT-5 ran 72 weeks in 751 adults and was published in the New England Journal of Medicine in 2025 (PMID 40353578). Everyone took the highest dose they could tolerate.

Average weight change at 72 weeks was 20.2% down on tirzepatide and 13.7% down on semaglutide. In plainer terms: about a fifth of body weight on one, about an eighth on the other. Waists came down 18.4 cm and 13.0 cm.

Two things are worth knowing before treating that as settled. Everyone knew which drug they were taking — the trial was open-label — and knowing tends to nudge results. And the semaglutide side topped out at 2.4 mg, the strongest dose sold while the trial ran; a 7.2 mg version, Wegovy HD, was approved in March 2026, after the comparison was over.

The unpleasant part looked similar on both sides. The most common problems in each group were stomach and bowel related, mostly mild to moderate, and mostly during the weeks when the dose was climbing.

Wegovy has a pill. Zepbound does not.

This is the newest real difference between them, and for plenty of people it is the deciding one. Novo's tablet version of Wegovy was approved on 22 December 2025 as a new dosage form (Drugs@FDA, NDA 218316). It carries the same semaglutide as the shot, paired with an absorption helper so it survives the stomach, and comes as 1.5 mg, 4 mg, 9 mg and 25 mg tablets.

The trade is the morning routine. The tablet goes down on an empty stomach with no more than a small glass of water, swallowed whole, and then nothing to eat, drink or swallow — other medicines included — for at least half an hour. Zepbound's labeling lists pens and vials only. If daily-versus-weekly is the question you are stuck on, oral semaglutide covers it properly.

What each one costs if you are paying yourself

Both companies now sell direct at prices well below the pharmacy sticker. These were read from the manufacturers' own pages on 6 September 2026, and they change often.

Insurance is the wildcard, and usually not in your favour: many plans cover these drugs for type 2 diabetes and exclude them for weight, which is how two people on the same medicine end up with wildly different bills.

The compounded versions are the same molecules under different rules

Zepbound and Wegovy are brands. The molecules inside them are also prepared by compounding pharmacies against an individual prescription, which is a different legal category rather than a copy of the brand.

Promise dispenses tirzepatide as a compounded medication, which is different from an FDA-approved product: the formulation offered here — tirzepatide with vitamin B12 — is not FDA-approved. Compounded medications are not reviewed by the FDA for safety, effectiveness or quality. That status is a fact about a preparation, not a verdict on you: a licensed provider may still decide a compounded formulation suits a particular person, and that decision sits between you and your doctor.

A licensed provider reviews every request here and prescribes only when it is appropriate — not everyone qualifies, and being turned down is the review doing its job rather than failing you. For how these preparations are made and who answers for them, compounded tirzepatide has it.

What usually settles it

Not the head-to-head number, most of the time. A diagnosis of moderate to severe sleep apnea points one way. Established heart disease points the other. A strong dislike of needles points at the tablet, and so does a plan that covers one brand and not the other.

Tolerance decides more of these than people expect. Someone who stops in month two because of nausea has taken nothing at all, whatever a 72-week average says. Which is why the useful question is rarely which drug won a trial, and nearly always which one a clinician who has read your history thinks you can stay on.