Nucala denied by insurance? Appeal and win.
A Nucala denial is rarely the final answer. It is usually the start of a process. Nucala is a high-cost biologic, so plans almost always require prior authorization and frequently demand step therapy through a preferred biologic or proof that your blood eosinophil count meets a specific threshold. When the denial is overturned, it is most often because the appeal documents the eosinophilic diagnosis with labs, shows the prior therapies that failed, and maps each plan criterion to your chart line by line.
Reviewed by the Apellica Appeals Team · Updated June 2026
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Nucala (mepolizumab) is FDA approved as an add-on maintenance treatment for several eosinophil-driven conditions. It is approved for severe asthma with an eosinophilic phenotype in adults and children aged 6 and older. It is approved for chronic rhinosinusitis with nasal polyps (CRSwNP) in adults. It is approved for eosinophilic granulomatosis with polyangiitis (EGPA) in adults. It is approved for hypereosinophilic syndrome (HES) lasting 6 months or longer without a known secondary cause in patients aged 12 and older. In 2025 it was also approved as add-on maintenance treatment for adults with chronic obstructive pulmonary disease (COPD) with an eosinophilic phenotype. It works by blocking interleukin-5 (IL-5), the cytokine that drives the growth and survival of eosinophils.
Why Nucala gets denied
- Step therapy not satisfied: the plan requires a trial and failure of a preferred biologic such as dupilumab, benralizumab, or reslizumab, or of high-dose inhaled corticosteroid plus a controller, before it will cover Nucala.
- Blood eosinophil count not documented or below the plan threshold: many plans require a count of at least 150 cells per microliter (or higher for EGPA, HES, and COPD), drawn within a defined lookback window.
- Prior authorization criteria not fully documented: the chart is missing proof of the eosinophilic phenotype, exacerbation history, optimized background therapy, or specialist involvement.
- Non-formulary or tier placement and site-of-care or self-administration issues: Nucala may be off formulary, placed on a high specialty tier, or routed through a specific pharmacy benefit, triggering an automatic denial.
What a winning appeal includes
- A clear diagnosis with the correct ICD-10 code (for example J45.x for severe eosinophilic asthma, J33.x for nasal polyps, M30.1 for EGPA, D72.1 for hypereosinophilia, or J44.x for COPD) tied to the eosinophilic phenotype.
- A documented blood eosinophil count that meets the plan's threshold, with the date and value, plus the exacerbation, hospitalization, or oral steroid history that shows uncontrolled disease.
- A record of prior therapies tried and their outcome, including high-dose inhaled corticosteroids, controllers, oral corticosteroids, and any preferred biologic that failed or caused intolerance or was contraindicated.
- A letter of medical necessity from the prescribing specialist that maps each of the plan's own published criteria to a specific line in the chart and confirms continued background therapy.
How we approach the appeal
First identify whether the denial is a formulary or tier problem or a clinical prior authorization or medical necessity problem, because each takes a different path. If Nucala is non-formulary or on a disfavored tier, file a formulary or tier exception arguing the preferred alternatives are inappropriate, ineffective, or contraindicated for your eosinophilic phenotype. If the denial is clinical, request the plan's written Nucala coverage policy and answer it criterion by criterion, quoting the plan's own language (for example, "blood eosinophil count of at least 150 cells per microliter" or "trial and failure of a preferred biologic within the past year"), then escalate to peer-to-peer review and, if needed, external independent review within your state's deadline.
Nucala appeal letter template
Copy this Nucala appeal letter, fill in the brackets, and send it within your deadline. It is built on what overturns IL-5 inhibitor (anti-interleukin-5 monoclonal antibody) denials.
[Date] [Your name] · Member ID [ID] · Rx claim # [#] [Insurer or PBM] - Appeals Department Re: Appeal of Nucala denial I am appealing the denial of Nucala (mepolizumab). I request that the denial be overturned and Nucala approved. 1. The denial. [Insurer] denied Nucala stating, verbatim: "[paste the exact denial reason from your letter]." 2. Medical necessity. Nucala is medically necessary for my condition. First identify whether the denial is a formulary or tier problem or a clinical prior authorization or medical necessity problem, because each takes a different path. If Nucala is non-formulary or on a disfavored tier, file a formulary or tier exception arguing the preferred alternatives are inappropriate, ineffective, or contraindicated for your eosinophilic phenotype. If the denial is clinical, request the plan's written Nucala coverage policy and answer it criterion by criterion, quoting the plan's own language (for example, "blood eosinophil count of at least 150 cells per microliter" or "trial and failure of a preferred biologic within the past year"), then escalate to peer-to-peer review and, if needed, external independent review within your state's deadline. 3. Step-therapy or formulary exception (if that was the reason): I have tried and failed [preferred drug(s)], with pharmacy records attached, or the preferred alternative is contraindicated because [reason]. I request a formulary or step-therapy exception. 4. My request. Approve Nucala within the timeframe required by law. If the denial is upheld, please provide the specific criteria used, the reviewing clinician's credentials, and external-review instructions. Attached: prescriber letter of medical necessity, pharmacy and prior-trial records, and supporting clinical notes. Sincerely, [Your name]
Want it built and filed for you? Use the free generator, or have Apellica do it.
Internal appeals: 30 days pre-service, 60 days post-service, 72 hours urgent. File within 180 days of the denial.
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- · The denial letter and your Explanation of Benefits (EOB)
- · Insurance ID, plan name, and the claim or prior-authorization number
- · Diagnosis with ICD-10 code and the prescriber's clinical notes
- · A record of treatments already tried and how they worked
Appealing a Nucala denial by insurer
The path depends on who manages your benefit. The most common:
Coverage runs through the pharmacy benefit. Appeal the coverage determination and, when the drug is non-formulary, file a formulary or tier exception with a provider attestation that covered alternatives are unsuitable.
Publishes detailed prior-authorization criteria. A denial usually means a criterion was not documented. Appeal through a coverage review, with a formulary exception for excluded drugs.
Administers many UnitedHealthcare and employer plans. Appeals and exceptions follow the plan's published PA criteria; expedited review exists for urgent cases.
Internal appeal first, then independent external review. Pre-service decisions are generally made within 30 days, urgent within 72 hours.
Internal appeals and external review; pharmacy denials often route through OptumRx criteria.
Independent state plans, so criteria vary. Match the appeal to your specific BCBS plan, internal appeal first, then external review.
Frequently asked questions
My plan says I have to try dupilumab or benralizumab before Nucala. Can I appeal that?
Yes. Step therapy can be appealed. If a preferred biologic was already tried and did not work, caused side effects, or is contraindicated for you, document that clearly and the requirement can usually be waived. If your specialist believes Nucala is the right first choice for your specific eosinophilic condition, the letter of medical necessity should explain why and ask for a step therapy exception under your plan's policy and any applicable state step therapy law.
Why does the insurer keep asking for my eosinophil count, and what number do they want?
Nucala targets eosinophils, so plans use the blood eosinophil count to confirm the eosinophilic phenotype. Many plans require at least 150 cells per microliter for severe asthma and COPD, while EGPA and HES generally require higher counts, often 1,000 cells per microliter or more. The exact threshold and lookback window vary by plan and indication, so check the written policy and submit a lab result with the date and value that meets it.
Is Nucala covered under my medical benefit or my pharmacy benefit?
It depends on how it is given and how your plan is structured. Nucala can be self-injected at home with a prefilled pen or syringe, which usually falls under the pharmacy benefit, or administered in a clinic, which may fall under the medical benefit. A denial sometimes happens simply because the claim went to the wrong benefit or pharmacy. Confirm which benefit your plan requires and which in-network or specialty pharmacy it must be filled through before resubmitting.
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Start Your AppealThis page provides general information about appeal strategy. It is not legal or medical advice. Apellica is not a law firm. Outcomes depend on documentation, plan terms, and timing.