How to Fight Insurance Denials for Long COVID Treatment

Long COVID—also called Post-Acute Sequelae of SARS-CoV-2 infection (PASC)—affects an estimated 17 million Americans who continue to experience debilitating symptoms months or years after their initial COVID-19 infection. Despite WHO recognition in 2021, an ICD-10 code (U09.9) in clinical use since October 2021, and a growing body of research documenting severe functional impairment, insurers routinely deny coverage for evidence-based Long COVID care. Common denials target multidisciplinary clinic evaluations, cognitive rehabilitation, POTS pharmacotherapy, low-dose naltrexone (LDN), extended Paxlovid courses, hyperbaric oxygen therapy (HBOT), and even basic autonomic testing. Insurers often classify these treatments as "experimental," "not medically necessary," or "self-care"—despite the fact that many patients are bedbound, unable to work, and experiencing measurable autonomic, cognitive, and cardiopulmonary dysfunction.

Why Insurers Deny Long COVID Treatment

Insurers use a handful of template denial reasons that recur across all major payers. Understanding these patterns helps you craft a targeted appeal.

1. "Long COVID is not a recognized diagnosis" or "U09.9 is not a covered condition"

Some insurers still claim Long COVID lacks clinical validity, even though the WHO published a case definition in 2021, the CDC maintains a dedicated Long COVID page, and ICD-10-CM added U09.9 specifically for post-COVID conditions in October 2021. This denial is often paired with language like "symptom complex" or "post-viral syndrome of unclear etiology."

2. "Treatment is experimental / investigational / not proven effective"

This is the most common template for denying multidisciplinary clinics, LDN, extended Paxlovid, HBOT, and transcutaneous vagus nerve stimulation. Insurers cite the absence of large-scale randomized controlled trials (RCTs) and FDA approval for Long COVID-specific indications, even when the proposed treatments are FDA-approved for other conditions or recommended by leading academic medical centers.

3. "Not medically necessary / symptom management available with conservative therapy"

Insurers argue that Long COVID symptoms can be managed with rest, hydration, over-the-counter medications, or standard physical therapy. This denial ignores the documented phenomenon of post-exertional malaise (PEM), where traditional graded exercise therapy causes severe symptom worsening and functional decline—a distinction critical to Long COVID care.

4. "Graded exercise therapy is the standard of care for fatigue / deconditioning"

Some insurers approve only traditional graded exercise or pulmonary rehab protocols, which are contraindicated in patients with PEM. When patients or physicians request PEM-aware pacing protocols instead, insurers deny these as "non-standard" or "not supported by guidelines," despite consensus statements from leading Long COVID programs warning against graded exercise in PEM-positive patients.

5. "Compounded medications / off-label use not covered"

Denials for low-dose naltrexone (LDN)—typically compounded at 1.5-4.5 mg, far below the FDA-approved 50 mg dose for opioid dependence—cite formulary restrictions or off-label use policies. Similarly, extended or repeat courses of Paxlovid (nirmatrelvir/ritonavir) for persistent viral reservoir or rebound symptoms are denied as "not FDA-approved for chronic use."

The Citations Insurers Respect

When appealing, reference specific guidelines, consensus statements, and peer-reviewed trials by name and year. Vague references to "medical literature" will not overcome a denial. The citations below are those currently recognized by major insurers and cited in successful appeals:

• WHO clinical case definition for post COVID-19 condition (2021): Symptoms persisting ≥3 months from acute infection, lasting ≥2 months, not explained by alternative diagnosis.
• ICD-10-CM U09.9 (effective October 1, 2021): Official diagnostic code for Post COVID-19 condition, unspecified.
• IOM 2015 ME/CFS diagnostic criteria: Many Long COVID patients meet criteria for myalgic encephalomyelitis/chronic fatigue syndrome (ME/CFS), particularly those with PEM, cognitive impairment, and orthostatic intolerance. The Institute of Medicine (now National Academy of Medicine) criteria provide a validated framework insurers recognize.
• DePaul Symptom Questionnaire for Post-Exertional Malaise: A validated instrument used to document and quantify PEM severity.
• 2-day cardiopulmonary exercise testing (CPET): Objective measure of PEM showing significantly reduced VO2max and ventilatory threshold on day 2 after maximal exertion on day 1.
• Tilt-table testing and 10-minute active stand test for POTS diagnosis: Postural Orthostatic Tachycardia Syndrome (POTS) is diagnosed when heart rate increases ≥30 bpm (≥40 bpm in ages 12-19) within 10 minutes of standing, without orthostatic hypotension. This is a recognized autonomic disorder with established diagnostic criteria.
• Mount Sinai, Stanford PACS Clinic, Johns Hopkins PACT, and Bateman Horne Center multidisciplinary models: Leading academic programs that have published consensus approaches to Long COVID management, emphasizing multidisciplinary evaluation and individualized treatment plans.
• Zilberman-Itskovich HBOT protocol (Shamir Medical Center, published 2022): Hyperbaric oxygen therapy protocol showing improvement in cognitive and physical symptoms in Long COVID patients with objective imaging changes.
• Hummel olfactory training protocol: Evidence-based approach for anosmia/parosmia using four odorants twice daily, validated in multiple studies.

How to Argue Against Each Denial Reason

Denial: "Long COVID is not a recognized diagnosis"

Your counter-argument:

1. Cite the WHO case definition (2021) and note that it has been adopted by CDC, NIH, and leading medical organizations worldwide.

2. Include the ICD-10 code U09.9 on all claims and appeals. Point out that ICD-10 codes are maintained by CMS and WHO specifically for billing and diagnosis—if insurers accept ICD-10 coding (which they must), they cannot simultaneously claim the diagnosis is invalid.

3. Attach your physician's clinical documentation of symptom onset relative to confirmed SARS-CoV-2 infection, duration ≥3 months, and exclusion of alternative diagnoses. If you had a positive PCR, antigen test, or antibody test, include that. If your diagnosis was clinical (during a surge when testing was unavailable), note this explicitly.

4. Reference NIH RECOVER Initiative: The National Institutes of Health has committed over $1 billion to Long COVID research, enrolling tens of thousands of patients. This is not an unrecognized condition.

Denial: "Treatment is experimental / investigational"

Your counter-argument:

1. For multidisciplinary clinics: Cite the models published by Mount Sinai, Stanford PACS, Johns Hopkins PACT, and Bateman Horne Center. Note that multidisciplinary evaluation is standard of care for complex chronic conditions (similar to rheumatology, neurology, or chronic pain programs). Attach your physician's letter explaining why your symptom burden (e.g., POTS, PEM, cognitive impairment, respiratory dysfunction) requires coordinated subspecialty input.

2. For POTS pharmacotherapy (midodrine, fludrocortisone, ivabradine, propranolol, pyridostigmine/Mestinon): These are FDA-approved medications commonly used for autonomic disorders. Attach your tilt-table or 10-minute stand test results showing diagnostic POTS criteria. Emphasize that POTS is a recognized diagnosis (not experimental) and that these medications are first-line treatment per Dysautonomia International and American Autonomic Society consensus.

3. For LDN (low-dose naltrexone): Acknowledge that LDN is off-label and compounded, but note that off-label prescribing is legal, common, and medically appropriate when evidence supports it. Cite peer-reviewed case series and small trials showing benefit in post-viral fatigue and neuroinflammatory conditions. Emphasize that standard-dose naltrexone (50 mg) is FDA-approved; LDN uses the same drug at a lower, immune-modulating dose. Request exception to formulary policy based on lack of effective alternatives.

4. For extended or repeat Paxlovid: Note that while not FDA-approved for chronic use, extended antiviral courses are being studied in NIH RECOVER trials and used at leading Long COVID centers for patients with evidence of persistent viral reservoir or rebound symptoms. Attach physician rationale and any labs or imaging supporting ongoing viral activity or inflammation.

5. For HBOT: Cite the Zilberman-Itskovich protocol (2022) published in peer-reviewed journals, showing objective cognitive and physical improvement with imaging correlates. Note that HBOT is FDA-cleared for multiple indications and that the protocol used in Long COVID is identical to protocols covered for other conditions (e.g., traumatic brain injury, radiation injury).

6. For cognitive rehabilitation and PEM-aware physical therapy: These are established, billable services (CPT codes exist). The modification is avoiding graded exercise in favor of pacing—this is not experimental; it is individualized care based on documented PEM. Attach DePaul PEM Questionnaire results or 2-day CPET showing objective PEM.

Denial: "Not medically necessary / conservative therapy sufficient"

Your counter-argument:

1. Document functional impairment objectively: Attach work status (FMLA dates, reduced hours, disability application), ADL limitations (hours upright per day, need for caregiver support, mobility aids), and validated questionnaires (Fatigue Severity Scale ≥4, PROMIS Fatigue T-score ≥60, MoCA showing cognitive impairment, mMRC dyspnea scale ≥2).

2. List all conservative treatments already tried and failed: Rest, hydration, sleep hygiene, pacing, over-the-counter NSAIDs, standard physical therapy. Note dates, duration, and lack of meaningful improvement. If any treatment caused worsening (e.g., graded exercise triggering PEM crash), document this in detail with dates and duration of relapse.

3. Explain why the proposed treatment is the next appropriate step: For example, "Patient has failed 6 months of conservative management and continues to meet IOM 2015 ME/CFS criteria with severe PEM. Multidisciplinary evaluation is necessary to coordinate autonomic testing, cognitive rehab, and pharmacotherapy for POTS—none of which can be addressed by a single-specialty provider or self-care."

4. Attach treating physician's letter of medical necessity that explicitly states why the treatment is necessary, not elective or experimental. The letter should reference specific clinical findings, test results, failed prior therapies, and how the proposed treatment addresses documented impairments.

Denial: "Graded exercise therapy is the standard of care"

This is the most dangerous denial pattern because following the insurer's recommendation can cause severe, long-lasting harm.

Your counter-argument:

1. Document PEM explicitly: Use the DePaul Symptom Questionnaire for PEM or attach 2-day CPET results showing reduced VO2max and ventilatory threshold on day 2. If you have already experienced a PEM crash after physical therapy or graded exercise, document the date, the activity that triggered it, and the duration and severity of the crash (e.g., "bedbound 7 days," "unable to work for 3 weeks," "required emergency room visit").

2. Cite IOM 2015 ME/CFS criteria and consensus statements from Long COVID clinics: The IOM report explicitly states that exertion beyond a patient's energy envelope can worsen symptoms and delay recovery. Leading Long COVID programs (Mount Sinai, Stanford, Bateman Horne) have published statements warning against graded exercise therapy in PEM-positive patients and recommending pacing instead.

3. Request PEM-aware physical therapy or pacing instruction, NOT graded exercise: These are billed under the same CPT codes but involve activity pacing, heart-rate monitoring, and avoiding post-exertional symptom flares. Your physician should specify "PEM-aware PT with pacing, NO graded exercise" in the prior authorization request.

4. If the insurer continues to deny, request an independent medical review (IMR) or external review and submit all PEM documentation plus the IOM 2015 report and Long COVID clinic consensus statements. Emphasize patient safety: graded exercise in a PEM-positive patient is not just ineffective—it is contraindicated and harmful.

Denial: "Compounded medications / off-label use not covered"

Your counter-argument:

1. For LDN: Cite your plan's policy on off-label prescribing and compounded medications. Many plans allow exceptions when (a) no FDA-approved alternative exists for the condition, (b) the prescribing physician provides rationale, and (c) peer-reviewed evidence supports the use. Attach physician letter explaining why LDN is prescribed (e.g., immune modulation, neuroinflammation, mast cell stabilization) and why standard-dose naltrexone or alternative medications are not appropriate. Include any published case series or trials.

2. Request formulary exception: Most plans have a formal formulary exception process. Submit the exception request with supporting literature, physician letter, and documentation of failed alternatives (if applicable).

3. Note cost-effectiveness: LDN is inexpensive (typically $30-60/month from a compounding pharmacy). If the insurer's alternative is more expensive (or nonexistent), note this.

4. For extended Paxlovid: Attach physician rationale citing NIH RECOVER trial enrollment or published case series on viral persistence. Note that the drug is FDA-approved (just not for this duration) and that the risks of short-term antiviral use are well-characterized and minimal compared to ongoing Long COVID disability.

What We Do

We help patients and families fight Long COVID denials by preparing evidence-based appeal packets with the specific citations, test results, and medical documentation insurers require. We've worked with patients denied multidisciplinary care, POTS treatment, cognitive rehab, LDN, HBOT, and extended Paxlovid, and we know which arguments work. If you're facing a denial, we'll review your case, identify the strongest counter-arguments, and provide a structured appeal you can submit yourself or have your physician sign.

Sources

1. World Health Organization. "A clinical case definition of post COVID-19 condition by a Delphi consensus." WHO, October 6, 2021.

2. Centers for Disease Control and Prevention. "Long COVID or Post-COVID Conditions." CDC, updated 2024.

3. Institute of Medicine (National Academy of Medicine). Beyond Myalgic Encephalomyelitis/Chronic Fatigue Syndrome: Redefining an Illness. Washington, DC: The National Academies Press, 2015.

4. Jason LA, Sunnquist M, Brown A, et al. "Examining case definition criteria for chronic fatigue syndrome and myalgic encephalomyelitis." Fatigue: Biomedicine, Health & Behavior 2(1):40-56, 2014.

5. Systrom DM, Revesz D, Walkey AJ, et al. "Cardiopulmonary exercise testing in post-acute COVID-19 patients." Journal of the American College of Cardiology 2021.

6. Shaw BH, Stiles LE, Bourne K, et al. "The face of postural tachycardia syndrome – insights from a large cross-sectional online community-based survey." Journal of Internal Medicine 286(4):438-448, 2019.

7. Davis HE, Assaf GS, McCorkell L, et al. "Characterizing long COVID in an international cohort: 7 months of symptoms and their impact." EClinicalMedicine 38:101019, 2021.

8. Zilberman-Itskovich S, Catalogna M, Sasson E, et al. "Hyperbaric oxygen therapy improves neurocognitive functions and symptoms of post-COVID condition: randomized controlled trial." Scientific Reports 12:11252, 2022.

9. Hummel T, Rissom K, Reden J, et al. "Effects of olfactory training in patients with olfactory loss." Laryngoscope 119(3):496-499, 2009.

10. Bateman L, Bested AC, Bonilla HF, et al. "Myalgic Encephalomyelitis/Chronic Fatigue Syndrome: Essentials of Diagnosis and Management." Mayo Clinic Proceedings 96(11):2861-2878, 2021.

11. Komaroff AL, Lipkin WI. "Insights from myalgic encephalomyelitis/chronic fatigue syndrome may help unravel the pathogenesis of postacute COVID-19 syndrome." Trends in Molecular Medicine 27(9):895-906, 2021.

12. National Institutes of Health. "NIH launches new initiative to study 'Long COVID.'" NIH RECOVER Initiative, 2021.