Why are prescription drug prices down 4.5% from a year ago?

The short answer

• Prescription drug prices fell 4.5% over the 12 months to September 2026, dropping while overall inflation rose 3.7%, driven by federal price negotiation and out-of-pocket caps under the Inflation Reduction Act alongside antitrust settlements with major pharmacy benefit managers. [1] [2] [3] [4]
• Over the five years leading to September 2026, prices rose just 4.2% as large-scale biosimilar adoption and Medicare inflation rebate penalties countered steep launch prices for newly developed specialty drugs. [5] [6] [7]

What's driving the price

Political, regulatory and trade factors

• Medicare drug price negotiation and Part D out-of-pocket caps (Jan 2025 to Sep 2026), Centers for Medicare and Medicaid Services: The Centers for Medicare and Medicaid Services put negotiated Maximum Fair Prices for 10 high-spend Part D drugs into effect on January 1, 2026, following the introduction of a $2,000 annual out-of-pocket Medicare Part D cap in 2025 that adjusted to $2,100 in 2026. [pushed prices down] [3] [8] [9] [10]
• Antitrust enforcement and consent orders against pharmacy benefit managers (Sep 2024 to Sep 2026), Federal Trade Commission: Following an administrative lawsuit against the three largest pharmacy benefit managers in September 2024 over inflated insulin list prices, the Federal Trade Commission finalized settlements with Express Scripts in February 2026 and Caremark in July 2026 to delink administrative fees from list prices and pass through point-of-sale rebates. [pushed prices down] [4] [11] [12] [13]
• Statutory inflation rebate penalties for manufacturer price increases (Oct 2022 to Sep 2026), Centers for Medicare and Medicaid Services: The Centers for Medicare and Medicaid Services required drugmakers to pay rebates if they raised Medicare Part B and Part D drug prices faster than the rate of general inflation, disincentivizing traditional annual list price hikes across brand medications. [pushed prices down] [6] [8]

Macro factors: supply, weather, disease, energy

• Elevated launch prices for novel specialty drugs and metabolic treatments (Oct 2021 to Sep 2026): Heavy spending on diabetes and weight-loss GLP-1 medications like semaglutide, combined with launch prices for newly approved drugs rising 8% annually to a median exceeding $250,000 between 2020 and 2025, sustained upward pressure on overall five-year spending. [pushed prices up] [5] [17]

Retail, brand and seasonal factors

• Mass commercial substitution to lower-cost biosimilar biologics (Jul 2024 to Sep 2026): Pharmacy benefit managers shifted formularies away from originator biologics to biosimilar alternatives, including Humira biosimilars that reduced average net costs per unit by 34.4% between January 2024 and March 2025, and Stelara biosimilars that entered the market in 2025 at list discounts of up to 85%. [pushed prices down] [7] [14] [15]
• Expansion of transparent cash-pay pharmacy channels (Feb 2026 to Sep 2026): Consumer pharmacy platforms such as Mark Cuban Cost Plus Drug Company and the launch of the direct-to-consumer TrumpRx site in February 2026 provided discounted cash prices on hundreds of medications directly to consumers, bypassing standard retail and intermediary markups. [pushed prices down] [2] [16]

Supply chain right now

• Drug discovery and clinical trials (stable): Research and development spending remains intensive while median launch prices for newly approved specialized therapies surpass $250,000. [5]
• Active pharmaceutical ingredient synthesis and drug manufacturing (stable): Bulk chemical and biologic manufacturing inputs remain steady as generic and biosimilar producers scale output to meet patent expirations. [15]
• Pharmacy benefit management and formulary contracting (moderate): Intermediary rebate structures and spread-pricing models are being restructured under regulatory scrutiny and antitrust consent orders. [4] [13] [18]
• Retail pharmacy dispensing and patient point-of-sale (critical): Direct consumer costs at pharmacy counters are falling as Medicare benefit caps, biosimilar transitions, and point-of-sale rebates take effect. [4] [8] [19]

Researched 2026-10-18 with Google Search. Every point links to its sources; unsourced claims were removed.

Prescription drugs prices, last 12 months

Source: U.S. Bureau of Labor Statistics, Consumer Price Index (CPI-U), series CUUR0000SEMF01.

Sources

1. How the Inflation Reduction Act Is Affecting the Cost of Prescription Drugs During 2026 | Serving Those Who Serve (stwserve.com)
2. Prescription Drug Prices Drop Even Faster Than in First Trump Administration—Hospital Price Inflation Still Hot (paragoninstitute.org)
3. Key Facts About Medicare Drug Price Negotiation | KFF (kff.org)
4. Duane Morris LLP - Pharmacy Benefit Manager Reaches Settlement with FTC Requiring Changes to Drug Pricing and Practices (duanemorris.com)
5. Prescription Drug Launch Price Trends Before and After the Inflation Reduction Act | PORTAL (portalresearch.org)
6. Medicare Inflation Rebate Program | CMS (cms.gov)
7. evernorth.com (evernorth.com)
8. medicarerights.org (medicarerights.org)
9. Inflation Reduction Act & Medicare Part D (uhc.com)
10. Selected Drugs and Negotiated Prices | CMS (cms.gov)
11. FTC Sues Prescription Drug Middlemen for Artificially Inflating Insulin Drug Prices (ftc.gov)
12. FTC Secures Major Settlement with Caremark, Resolving Antitrust Case Against Second Drug Middleman (ftc.gov)
13. FTC Settlement Affects Drug Pricing Practices and Reshoring (conference-board.org)
14. Drug Channels: The Stelara Biosimilar Price War: How PBM-Affiliated Private Labels Are Reshaping the Market (rerun) (drugchannels.net)
15. Stelara biosimilars enter US market with 85% discount in 2025 (gabionline.net)
16. CanAmerica Plus (canamericaplus.com)
17. pubmed.ncbi.nlm.nih.gov (pubmed.ncbi.nlm.nih.gov)
18. 2024 - FTC and Congress take action against PBMs for price gouging - ACAAI Member (college.acaai.org)
19. U.S. Medicine Use Trends 2026 (iqvia.com)

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