Even at Zero Cost, One in Ten Prescriptions Never Gets Filled
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Across branded medicines, roughly 10% of new prescriptions go unfilled within 30 days even when the patient owes nothing at all according to IQVIA data released in 2025. Cost is the strongest thing anyone has measured, and taking it to zero still leaves a tenth of people who never start.
Who This Helps
This is market background rather than instructions. It's for you if you want to understand why coverage and copay design look the way they do. If you're choosing a plan, our guide to checking coverage is the practical one.
The curve
IQVIA published 2025 claims data on how often new-to-brand prescriptions go unfilled within 30 days, across all payers, sorted by what the patient owes (IQVIA):
- Nothing owed: 10%.
- Under $20: 14% to 15%.
- $30 to $50: 18% to 20%.
- $50 to $75: 27%.
- $125 to $250: 44%.
- Over $250: 58%.
One thing that’s important to keep in mind: this dataset covers branded medicines across all categories and has no GLP-1 breakout anywhere in its text or charts. It's a backdrop for how cost and behavior relate generally, it isn't a measurement of this market.
What the floor tells you
IQVIA reads its own data this way: patients facing low or no out-of-pocket responsibility continue to abandon therapy at roughly 10 to 15%, which indicates that affordability is only one of several factors influencing whether treatment starts. The company describes the relationship as multifactorial.
That's a more honest framing than most coverage of drug pricing manages. Free doesn't get you to everyone. Somewhere around one person in ten walks away from a prescription that costs them nothing, and the data shows the pattern without explaining it. Nobody has measured what that tenth is made of and it could be due to access issues, like difficulty getting to a pharmacy to fill the prescription, to fear of side effects that weren’t discussed fully when prescribed.
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Where the money actually buys something
The gap between $0 and $20 is about five percentage points. The gap between $20 and $250 is about forty-five. So the return on reducing what someone owes isn't spread evenly, and it isn't concentrated at the bottom of the range.
IQVIA draws the same conclusion, saying the most significant opportunity for affordability interventions sits among patients facing higher levels of cost exposure, and that reducing that burden may help preserve treatment initiation that would otherwise be lost. This may be fueling the move to create copay programs or offer savings card programs from manufacturers who want to give people a little nudge with the best effect.
Read practically, that means getting a copay from $250 down to something manageable does far more than getting it from $20 to nothing. A program that lands people in the $20 to $50 range captures most of the available effect. Chasing the last few dollars to zero buys comparatively little, and it shows there’s little incentive to companies offering truly $0 copay plans.
Why this matters for GLP-1s specifically
The dataset doesn't separate them out, so treat what follows as context rather than measurement. But GLP-1s have mostly sat at the far end of that curve, where the line is steepest. A list price in the hundreds per month puts an uninsured or poorly covered patient in the band where more than half of new prescriptions go unfilled.
It also explains why the copay figures attached to recent coverage programs cluster where they do rather than at zero. Fifty dollars sits in the part of the curve where most of the behavioral gain has already been captured.
Starting and staying are different problems
Going unfilled happens at the counter. Stopping happens months later, and the reasons differ. In a chart review of 288 patients at a single health system who started in 2022 or 2023 and later stopped, financial reasons accounted for 47.6%, side effects 14.6% and supply shortages 11.8% (Cleveland Clinic). Financial reasons led at every point in the first year.
Persistence, or the rate people stay on medications long-term, has been improving. Among commercially insured adults without diabetes, one-year persistence rose from 33.2% for people starting in 2021 to 60.9% for those starting in the first half of 2024 (Journal of Managed Care and Specialty Pharmacy), with the authors pointing to the resolution of the shortages as a possible reason. The widely repeated figure that roughly two thirds quit within a year describes an earlier cohort running 2018 to 2023 (JAMA Network Open), and quoting it as the current picture is where a lot of coverage goes wrong.
Cost pressure also shows up without anyone stopping a prescription. Among insured people taking a GLP-1, 27% report paying the full cost themselves and 56% say the medication is hard to afford (KFF).
Final Takeaway
Two things are true at once, and most arguments about drug pricing pick one. Patients paying for these medications are more interested in paying the least possible, but companies making medications right now are more interested in bringing high pricing down to moderate, not in the last stretch to free.
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Frequently Asked Questions
Why would someone not fill a prescription that costs nothing?
The data shows the pattern and doesn't explain it. IQVIA calls the relationship multifactorial and says affordability is one of several factors. Anyone offering a confident single explanation is going past what's been measured.
Does this data say anything about GLP-1 abandonment specifically?
No. The dataset covers branded medicines generally and contains no GLP-1 figures anywhere. We use it here only as context for how cost and behavior relate at the pharmacy counter.
Would making GLP-1s free fix access?
It would help, and it wouldn't finish the job. The measured difference between owing nothing and owing under $20 is about five percentage points, while the difference between $20 and $250 is roughly forty-five. Most of the gain is in the middle of the range.
Find a provider in your state
Answer a few questions and see live pricing from the providers that ship where you live.
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Written by
Lauren PescarusLauren Pescarus is a team member with GLP Winner where she works on marketing, content creation, and operations. She has over 10 years experience in the content creation space, including in the GLP-1 space where she works to stay on top of access news, research updates, and lifestyle tips guided by science.