Tirzepatide: how it works, cost and where to get it

What tirzepatide is

The label calls tirzepatide "a GIP receptor and GLP-1 receptor agonist." GIP and GLP-1 are hormones the gut releases after eating. Tirzepatide binds to and switches on the receptors for both ^[1]. That makes it a GLP-1 medicine, but not only a GLP-1 medicine: it is a dual agonist. The label names no other target, so it is not a GLP-2 drug, and it is not insulin.

It is not semaglutide either. Semaglutide (Wegovy, Ozempic) acts on the GLP-1 receptor alone. Our semaglutide guide covers that drug, and Wegovy vs Zepbound compares the two.

Is tirzepatide a peptide?

Yes, in practice. The label describes tirzepatide as based on the GIP sequence, with aminoisobutyric acid at positions 2 and 13 and a 20-carbon fatty diacid attached through a linker. Its molecular weight is 4,813.53 Da ^[1]. The fatty acid lets it bind to albumin in the blood, which stretches its half-life to about 5 to 6 days and allows weekly dosing ^[1].

What color is tirzepatide, and why is mine red?

Zepbound is "a clear, colorless to slightly yellow, sterile solution." The label says not to use it if you see particles or discoloration ^[1]. Single-dose pens and vials list sodium chloride, sodium phosphate and water as inactive ingredients; multi-dose vials and KwikPens also contain benzyl alcohol, glycerin and phenol ^[1]. A red or pink product is not the FDA-approved drug as labeled. Some compounded products are blends with added vitamins; in September 2026 FDA called compounded tirzepatide with niacinamide an "essentially copy" in a warning letter to Empower Pharmacy ^[6]. If your product does not match what the pharmacy label describes, do not inject it. Call the pharmacist.

How tirzepatide works in the body

• Appetite. "Tirzepatide decreases calorie intake. The effects are likely mediated by affecting appetite." Both receptors sit in brain regions that control appetite ^[1].
• Stomach emptying. It slows how fast food leaves the stomach. The delay is largest after the first dose and fades over time ^[1].
• Body composition. The label says weight loss comes with more fat loss than lean mass loss ^[1]. In a SURMOUNT-1 substudy of 160 people, fat mass fell 33.9% and lean mass 10.9% at 72 weeks ^[7]. More in how to keep muscle on a GLP-1.
• Timing. Blood levels peak about 24 hours after a dose (range 8 to 72 hours) and reach steady state after 4 weekly doses ^[1].

For the bigger picture across the drug class, read how GLP-1 medicines work.

Is tirzepatide FDA-approved? Zepbound vs Mounjaro

The two FDA-approved tirzepatide brands

Brand	Approved for	First approved	Top dose
Zepbound	Weight reduction and long-term maintenance in adults with obesity, or overweight with a weight-related condition; moderate to severe obstructive sleep apnea in adults with obesity [2]	Nov 8, 2023 for weight [8]; Dec 20, 2024 for sleep apnea [9]	15 mg weekly [2]
Mounjaro	Blood sugar control in adults and children 10 and older with type 2 diabetes; lowering major heart risks in high-risk adults with type 2 diabetes [3]	May 13, 2022 [10]	15 mg weekly adults, 10 mg children [3]

Doses and how often to take it

Zepbound starts at 2.5 mg once a week for 4 weeks. That dose is only for getting started. The dose then goes to 5 mg and can rise in 2.5 mg steps after at least 4 weeks on the current dose. Maintenance doses for weight are 5, 10 or 15 mg; for sleep apnea, 10 or 15 mg ^[2]. You can inject any time of day, with or without meals, in the abdomen or thigh, or the back of the upper arm if someone else gives it ^[3].

It is a weekly drug. You can move your dosing day as long as doses are at least 3 days (72 hours) apart. If you miss a dose, take it within 4 days; after that, skip it and go back to your usual day ^[2]. Taking it every 5 days is not a labeled schedule, so ask your prescriber before changing anything.

If you use a compounded vial, the number of units depends on the concentration printed on the pharmacy label. Follow your prescriber's instructions and the pharmacy label, and ask the pharmacist if anything is unclear. Details: tirzepatide dosage, how to use tirzepatide, and microdosing tirzepatide.

What trials show

Average weight change in tirzepatide trials

Trial	Who	Result
SURMOUNT-1	Adults with obesity or overweight, no diabetes, 72 weeks	Average loss 15.0% (5 mg), 19.5% (10 mg), 20.9% (15 mg) vs 3.1% placebo [4]
Zepbound Study 2	Adults with type 2 diabetes, 72 weeks	Average loss 12.8% (10 mg), 14.7% (15 mg) vs 3.2% placebo [1]
SURMOUNT-5	Head to head with semaglutide, 72 weeks	Average loss 20.2% on tirzepatide vs 13.7% on semaglutide [11]
SURMOUNT-4	Stopped vs continued after 36 weeks on drug	People switched to placebo regained 14.0% of body weight from week 36 to 88; people who stayed on it lost another 5.5% [12]

Is tirzepatide stronger than semaglutide? In SURMOUNT-5, the one head-to-head trial, people on tirzepatide lost more weight on average and were more likely to reach 25% loss; stomach and bowel side effects were the most common in both groups ^[11]. That trial does not settle which is safer.

Is tirzepatide safe? Side effects and who should not take it

Most common side effects in Zepbound weight trials (percent of people)

Side effect	Placebo	5 mg	10 mg	15 mg
Nausea	8	25	29	28
Diarrhea	8	19	21	23
Vomiting	2	8	11	13
Constipation	5	17	14	11

The label carries a boxed warning: tirzepatide caused thyroid C-cell tumors in rats, and it is unknown whether it does in people. Anyone with a personal or family history of medullary thyroid carcinoma or MEN 2 should not take it ^[1]. Other label warnings cover severe stomach and bowel reactions (not recommended in severe gastroparesis), kidney injury from fluid loss, gallbladder disease, pancreatitis, allergic reactions, low blood sugar with insulin or a sulfonylurea, diabetic eye complications, and breathing in stomach contents during anesthesia or deep sedation ^[1][2].

Tirzepatide can make birth control pills less reliable. The label advises switching to a non-oral method or adding a barrier method for 4 weeks after starting and after each dose increase ^[3]. Zepbound should be stopped when pregnancy is recognized ^[1]. Other drug questions: tirzepatide interactions. Taking semaglutide and tirzepatide together is not recommended on the Zepbound label ^[2].

What tirzepatide costs

Tirzepatide prices, checked October 17, 2026

Route	Price	What to know	Source
Zepbound on LillyDirect (vial or KwikPen)	$299 (2.5 mg), $399 (5 mg), $449 (7.5 to 15 mg)	$449 needs a refill within 45 days; otherwise $499 (7.5 mg) or $699 (10 to 15 mg)	[5]
Zepbound with insurance that covers it	As little as $25	Savings card; not for Medicare or Medicaid; ends Dec 31, 2026	[13]
Zepbound on TrumpRx	From $299	Sends you to LillyDirect; listed original price $1,087	[14]
Zepbound KwikPen on Medicare	$50 copay	GLP-1 Bridge, for eligible Part D enrollees	[15]
Mounjaro list price	$1,112.16 per 28 days	Savings card brings covered fills to $25	[16][17]

What is compounded tirzepatide?

Compounded tirzepatide is mixed by a pharmacy rather than made by Lilly. It is not FDA-approved, and FDA does not review it for safety, effectiveness or quality ^[18]. During the shortage, pharmacies could make copies. FDA ruled the shortage resolved on December 19, 2024; its grace period ended March 5, 2025 for 503A pharmacies and March 19, 2025 for 503B outsourcing facilities ^[19]. A 503A pharmacy may now compound it only for a specific patient, and copies of an approved drug are barred unless the prescriber documents a change that makes a significant difference for that patient ^[19]. The Fifth Circuit upheld FDA's shortage decision on August 27, 2026 ^[20].

FDA had received more than 730 adverse event reports for compounded tirzepatide as of May 31, 2026 ^[18]. Is it safe? No one can say with the evidence FDA requires. Read compounded tirzepatide, research-use-only tirzepatide and our FDA warning letter tracker.

Is there a tirzepatide pill?

No FDA-approved one. The Zepbound and Mounjaro labels list only injections: single-dose pens and vials, and multi-dose vials and KwikPens ^[2]. Lilly's weight loss pill, Foundayo, contains a different drug, orforglipron ^[21]. See oral tirzepatide and Foundayo.

How to get tirzepatide

1. See a licensed clinician, in person or online, who can confirm the label fits you. Zepbound's weight indication covers adults with a BMI of 30 or more, or 27 or more with a weight-related condition ^[8].
2. Choose a pharmacy route: your own pharmacy with insurance, or LillyDirect self-pay with free home delivery or Walmart pickup ^[5].
3. Check the price at your maintenance dose, not just the starting dose.

Local options: tirzepatide near you. Online: how to get tirzepatide online.

All tirzepatide guides

• Zepbound: doses, cost and how to get it
• Mounjaro: what it is, how it works and what it costs
• Tirzepatide cost in 2026: brand, compounded and clinic prices
• Cheapest tirzepatide online, compared
• Where to get tirzepatide near you
• How to get tirzepatide online
• Tirzepatide side effects: what is common and what is serious
• How long Tirzepatide takes to work and how much weight people lose
• Tirzepatide dosage: doses, schedule and units to mg
• How to use Tirzepatide: injection sites, timing and missed doses
• Does Tirzepatide need to be refrigerated? Storage and travel
• What to eat and drink on Tirzepatide
• Tirzepatide with other medicines and health conditions
• What happens when you stop Tirzepatide
• Oral tirzepatide: what exists and what does not
• Microdosing tirzepatide: doses, cost and evidence
• Compounded tirzepatide: cost, legality and safety
• Does insurance cover Zepbound or Mounjaro? Plan by plan
• Wegovy vs Zepbound (semaglutide vs tirzepatide)
• Mounjaro vs Zepbound: same drug, different label