Express Scripts and Optum Rx set their 2026 tirzepatide formulary positions

Two of the largest pharmacy benefit managers in the United States have published their 2026 drug lists, and both treat tirzepatide products differently depending on the device and the condition being treated. Express Scripts' National Preferred Formulary lists Mounjaro, the tirzepatide brand for type 2 diabetes, as a covered injectable medication ^[1]. Optum Rx's Premium formulary also covers Mounjaro, but requires prior authorization, meaning a doctor must submit extra information before the plan pays for it ^[3].

For Zepbound, the tirzepatide brand approved for weight management, the two PBMs line up on the basic split between delivery devices but differ in how they describe it. Express Scripts' formulary exclusions document shows that vial-based versions of drugs can be dropped from coverage when a preferred alternative exists, and the Zepbound vial falls into that excluded category on the 2026 list, while the Zepbound pen remains listed as covered ^[1][2]. Optum Rx's Premium formulary places the Zepbound auto-injector, the pen, at Tier 2, its mid-range brand-name tier, with a prior authorization requirement, while the Zepbound solution, the vial, is marked excluded ^[3].

Tier 2 on the Optum Rx system covers what the formulary calls "mid-range cost preferred brand name" drugs, and the plan advises that using Tier 2 drugs instead of Tier 3 options can lower a patient's out-of-pocket cost ^[3]. Prior authorization, in Optum Rx's own definition, means the prescribing doctor has to give the plan more information before the medication is approved for coverage ^[3]. Express Scripts uses a similar review process for excluded drugs: a doctor can request a coverage exception through the company's online portal if there is a clinical reason a patient needs to stay on a drug that isn't on the preferred list ^[2].

Why it matters for patients

For someone using Zepbound, the practical effect depends entirely on which device they use. A patient on the Zepbound pen who is covered by an Express Scripts or Optum Rx plan built on these formularies would generally have their medication on the covered list, though Optum Rx members would still need a prior authorization approved first ^[1][3]. A patient using the Zepbound vial, which is often sold as a lower-cost option, could find it excluded from both plans' 2026 formularies, which typically means paying full price or switching to the pen version unless a doctor successfully appeals for an exception ^[1][2][3].

For people with type 2 diabetes on Mounjaro, both PBMs keep the drug covered, but coverage is not automatic. Prior authorization means a delay is possible while the prescriber submits paperwork, and coverage is not guaranteed even after that step ^[1][3]. None of the source documents describe what specific medical criteria a doctor must meet to get Mounjaro or Zepbound approved through prior authorization, so those details are not yet known from what's published here.

Both companies note that their lists are not complete and that actual coverage depends on the specific benefit plan a person has through their employer or insurer ^[1][3]. Members are directed to check their own plan materials or call the number on their prescription ID card to confirm whether these formulary positions apply to their coverage ^[1][2][3].

What happens next

Both formularies took effect January 1, 2026, and run through December 31, 2026, according to Express Scripts, though the company notes the list is subject to change during the year ^[1]. Optum Rx says medications can move to a different tier or be excluded from coverage on January 1 or July 1 of any year, meaning a review point could come again in mid-2026 ^[3]. Neither source specifies whether Zepbound vial coverage could be revisited before then.