82 clinics listing tirzepatide or its brands in Illinois

What is Tirzepatide?

Tirzepatide is the active ingredient in Mounjaro (for type 2 diabetes) and Zepbound (for weight loss). It is the first medication that targets two hunger hormones at once: GIP and GLP-1. By activating both, it produces stronger weight loss and blood sugar control than GLP-1-only medications like semaglutide at the doses the two have actually been compared at. In the largest clinical trial, people on the highest dose lost an average of 22.5% of their body weight. It beat Wegovy 2.4 mg in SURMOUNT-5, the only head-to-head trial of the two, though the newer 7.2 mg dose of Wegovy has never been tested against it.

Brand names

Tirzepatide is available as Mounjaro, Zepbound, manufactured by Eli Lilly.

Expected weight loss

In the main weight loss trial, people on tirzepatide 15 mg lost an average of 22.5% of their body weight over 72 weeks (about 17 months). That 22.5% is estimated assuming everyone stayed on treatment. Counting everyone who started, including those who stopped early, the average was 20.9%. This matters when you compare drugs, because the usual headline figure for Wegovy, 14.9%, is the counting-everyone number. The fair pairings are 20.9% against 14.9%, or 22.5% against 16.9%. At 10 mg, the average was 21.4%. Over a third of people on the highest dose lost 25% or more. For a 200-pound person, 22.5% is roughly 45 pounds.

Cost in Illinois

Without insurance, Tirzepatide typically costs Lilly lists Mounjaro at $1,112.16 per fill and Zepbound at $499 to $1,086.37 per fill, by product and dose (WAC as of January 1, 2026). A fill is one month: four pens for Mounjaro, 28 days for Zepbound. With insurance, costs range from Set by your plan's formulary, drug tier and deductible; manufacturer savings cards can lower it for eligible commercially insured patients. Compounded options may be available at $250-$550/month.

Savings programs: Eli Lilly offers the Zepbound Savings Card (commercially insured patients may pay as low as $25/month) and sells Zepbound direct through LillyDirect Self Pay as a single-patient-use KwikPen or a 4-count single-dose vial: $299 at 2.5 mg, $399 at 5 mg, $499 at 7.5 mg and $699 at 10 mg and above for a 28-day supply.