Nucala (mepolizumab) is an injectable biologic from GSK that blocks interleukin-5. FDA labeling covers severe eosinophilic asthma, eosinophilic granulomatosis with polyangiitis, hypereosinophilic syndrome, chronic rhinosinusitis with nasal polyps, and COPD with an eosinophilic phenotype. Adults and adolescents 12 and older with severe asthma get 100 mg every four weeks, which works out to 13 doses a year.
Two things make the cash number confusing. Nucala ships in four presentations at three different list prices, and it can be given three different ways: self-injected at home with the autoinjector, injected by staff in a doctor’s office, or given in a hospital outpatient clinic. The drug is identical in all three. The bill is not. Every figure below was verified on September 2, 2026, and this page covers money and paperwork only, not whether the drug is right for you.
What Does Nucala Cost Without Insurance?
GSK publishes Nucala’s wholesale acquisition cost (the manufacturer list price) in its state prescriber price disclosures, current as of January 2026. Texas’s Department of State Health Services separately collects January 1 list prices directly from manufacturers and publishes them in its 2026 Annual WAC Report. Texas’s figures for all four Nucala NDCs match GSK’s own disclosure to the cent, which is about as clean a two-source confirmation as drug pricing gets. The Medicare row comes from the CMS Part B payment limit file effective July 1 through September 30, 2026, built on first-quarter 2026 average sales price data.
| Nucala presentation or benchmark | Low | Average / typical | High |
|---|---|---|---|
| 100 mg/mL autoinjector, GSK list price | $3,990.98 | $3,990.98 | $3,990.98 |
| 100 mg/mL prefilled syringe, GSK list price | $3,990.98 | $3,990.98 | $3,990.98 |
| 100 mg single-dose vial, GSK list price | $3,674.88 | $3,674.88 | $3,674.88 |
| 40 mg/0.4 mL syringe (ages 6 to 11), GSK list price | $1,596.41 | $1,596.41 | $1,596.41 |
| Medicare Part B allowed amount, 100 mg (Q3 2026) | $3,228.10 | $3,228.10 | $3,228.10 |
| In-office injection administration, CPT 96372 (Medicare national) | $15.36 | $15.40 | $15.44 |
| NUCALA Copay Program (commercial insurance only) | $0 | $0 | $0 |
| GSK Patient Assistance Program (approved uninsured applicants) | $0 | $0 | $0 |
The honest cross-source range for one adult 100 mg dose of the drug itself is $3,228 to $3,991. At 13 doses a year, straight list price for the autoinjector is $51,882.74, and the Medicare benchmark works out to $41,965.30.
List price is not the same as Medicare’s price
Wholesale acquisition cost is what GSK charges wholesalers before any discount, rebate or chargeback, and GSK says so directly on the disclosure. Medicare’s Part B number is built from average sales price, which is net of most of those discounts, then marked up 6%. That is why the same 100 mg is $3,990.98 on one page and $3,228.10 on the other, a gap of about $763 per dose.
Neither number is what a specialty pharmacy quotes a cash customer, and quotes on drugs at this price point vary enough that a single phone call is not a market survey. If a pharmacy or clinic gives you a figure that matches nothing here, run it through our fair price checker before you pay.
The administration fee is the small number
CPT 96372, the code for a therapeutic subcutaneous injection, carries 0.46 total relative value units in the CMS 2026 physician fee schedule file released June 30, 2026. Against the 2026 conversion factors of $33.4009 and $33.5675, that is about $15.36 to $15.44 nationally. GSK’s own copay program caps administration help at $100 per administration, which is a reasonable ceiling for what a physician office actually bills a cash patient.
The number that moves is the facility fee. A hospital outpatient infusion suite bills its own charge on top of the drug and the injection, and that charge is what turns a $3,991 dose into a five-figure line item. Our guide to hospital price transparency explains how to pull a hospital’s posted cash rate before you agree to be treated there.
What Drives the Price
Which presentation is on the prescription. The autoinjector and the prefilled syringe both list at $3,990.98. The 100 mg vial, which has to be reconstituted by a professional, lists at $3,674.88. Same 100 mg of drug, $316.10 apart, purely on delivery device. If you are paying cash and a clinician is going to administer it anyway, ask whether the vial is an option.
Your dose, which the diagnosis sets. FDA labeling puts severe asthma at 100 mg every four weeks for ages 12 and up, and 40 mg every four weeks for children 6 to 11. Eosinophilic granulomatosis with polyangiitis and hypereosinophilic syndrome are dosed at 300 mg every four weeks, which means three autoinjectors and roughly triple the cost. COPD and nasal polyps are dosed at 100 mg. Confirm which line of the label your prescription is written against before you budget.
Where the injection happens. Home self-injection with the autoinjector costs the drug and nothing else. A physician office adds roughly $15 of Medicare-benchmarked administration. A hospital outpatient department adds a facility fee that no national file will tell you in advance. That single choice is worth more than every discount card on the market.
There is no biosimilar. FDA’s biosimilar product list, content current as of August 4, 2026, contains no mepolizumab product. Nucala has been sold in the US since its initial approval in 2015 and is still the only mepolizumab here. Unlike an older biologic where competition has arrived, there is nothing cheaper to substitute.
Whether the buyer gets 340B pricing. HRSA’s 340B Drug Pricing Program requires manufacturers that participate in Medicaid to sell covered outpatient drugs to qualifying safety-net providers at significantly reduced prices, capped at a statutory ceiling. Community health centers, disproportionate share hospitals and other covered entities buy at those prices, which is why the same injection at a federally qualified health center can be priced very differently than at a private specialty clinic.
Cash Price vs. Insurance
For Nucala, the split is unusually sharp. If you have commercial insurance, run the claim and enroll in the NUCALA Copay Program, which GSK advertises at as little as $0 per dose. The posted terms require a commercial medical or prescription plan, exclude anyone with Medicare Part B, Medicare Part D, Medicaid, Medigap, VA, Department of Defense or TRICARE coverage, and note that program maximums are set at GSK’s discretion. The program also pays up to $100 per administration, and that administration benefit counts against the annual maximum.
If you are uninsured, there is no cash-shopping strategy that gets you close. A discount card on a $3,991 specialty biologic is not the tool it is on a retail drug, and Nucala is not stocked at most neighborhood pharmacies anyway. The realistic path is the free-drug program, and it is worth applying even if you think your income is too high, because the Nucala-specific thresholds are more generous than GSK’s general program.
The awkward middle is a commercial plan that covers Nucala badly, with a specialty tier coinsurance of 30% or 40% against a list price near $4,000. In that situation the copay program is doing real work, but so is checking whether the same drug given in a doctor’s office rather than a hospital clinic changes your share of the bill.
How to Pay Less
-
Apply to the GSK Patient Assistance Program by name, using the Nucala track. The foundation publishes separate, higher income limits for Nucala than for GSK’s general program: $63,840 for a household of one in the 48 states and DC, $86,560 for two, $109,280 for three, $132,000 for four, and $22,720 for each additional person. Alaska runs from $79,800 to $165,000 and Hawaii from $73,440 to $151,800. You must live in the US, Puerto Rico or the US Virgin Islands and have no coverage for the product.
-
Choose the site of care deliberately. Home self-injection with the autoinjector removes the administration and facility charges entirely. If a clinician has to give it, a physician office is the cheaper venue. Before agreeing to a hospital outpatient clinic, ask for the total cash price including the facility fee in writing.
-
Ask a 340B clinic or community health center what they charge. Federally qualified health centers and other 340B covered entities buy covered outpatient drugs at deeply reduced statutory prices and many run sliding fee scales for the visit itself. Our guide to free and sliding-scale clinics covers how to find one and what to ask.
-
Fix a bill that already landed before you negotiate the next one. If a hospital or specialty pharmacy invoice arrived before assistance was approved, start with an itemized hospital bill so you can see the drug charge and the facility charge separately, then work through our medical bill negotiation guide. If the bill came from a hospital, charity care may erase the facility side outright, and our charity care checker will tell you whether you are likely to qualify.
-
Make sure the biologic is actually the cheapest thing that fits. Everything upstream of a biologic is priced in a different universe. Our guides to inhaler costs, Symbicort, Breztri, Advair, Spiriva, montelukast and albuterol without insurance show what the maintenance and rescue layers cost when paid in cash.
Bottom Line
Budget $3,228 to $3,991 for one 100 mg dose of Nucala in September 2026, plus about $15 if a physician office gives the injection and an unknown facility fee if a hospital does. Over a year at the adult severe-asthma schedule, that is $41,965 at the Medicare benchmark and $51,883 at GSK’s list price.
The realistic target for an uninsured patient is not a lower price, it is zero, through the GSK Patient Assistance Program. For the other severe-asthma biologic priced the same way, see our guide to Tezspire, and for the type-2 biologic that overlaps with Nucala across asthma, nasal polyps and COPD, see Dupixent. If you want a look at the inhaled triple therapy most patients try before any of these, Trelegy is the one to read.