A Phase 3 interventional study of naltrexone and Placebo in Post-acute COVID-19 Syndrome, sponsored by National Institute of Allergy and Infectious Diseases (NIAID). Not yet recruiting at 13 sites in United States. Open to participants aged 6 Years to 25 Years. Per ClinicalTrials.gov, last updated 2026-11-04.
Sponsored by National Institute of Allergy and Infectious Diseases (NIAID) · Phase 3, Interventional, and Treatment
This is a randomized, double-blind, placebo-controlled Phase 3 trial evaluating the efficacy and safety of a 16-week course of low-dose naltrexone (LDN) in approximately 1,300 participants aged 6 to 25 years with fatigue associated with Long COVID. Participants will be enrolled across three age cohorts (6-11, 12-17, and 18-25 years) and randomized 1:1 to receive LDN capsules or matching placebo capsules. LDN will be initiated at 1.5 mg daily and titrated weekly to a maximum tolerated dose of up to 4.5 mg daily. Randomization will be stratified by age cohort, and participants will also be randomized to a pharmacokinetic (PK) sampling window. Primary objective is to compare the change in fatigue severity from baseline to 16 weeks between participants aged 6 to 25 years with Long COVID randomized to a 16-week course of LDN or placebo.
This is a randomized, double-blind, placebo-controlled Phase 3 trial evaluating the efficacy and safety of a 16-week course of low-dose naltrexone (LDN) in approximately 1,300 participants aged 6 to 25 years with fatigue associated with Long COVID. Participants will be enrolled across three age cohorts (6-11, 12-17, and 18-25 years) and randomized 1:1 to receive LDN capsules or matching placebo capsules. LDN will be initiated at 1.5 mg daily and titrated weekly to a maximum tolerated dose of up to 4.5 mg daily. Randomization will be stratified by age cohort, and participants will also be randomized to a pharmacokinetic (PK) sampling window. Primary objective is to compare the change in fatigue severity from baseline to 16 weeks between participants aged 6 to 25 years with Long COVID randomized to a 16-week course of LDN or placebo. Secondary objectives: To compare the change in fatigue severity from baseline to 16 weeks between participants with Long COVID in age groups: 6 to 11 years, 12 to 17 years and 18-25 years. Each participant will be randomized to a 16-week course of LDN or placebo.
604 studies on the registry are indexed under Post-Acute COVID-19 Syndrome; 201 are open to participants now.
This study's planned enrollment of 1,300 is above the median of 60 across 416 interventional studies indexed under Post-Acute COVID-19 Syndrome.
Browse Post-Acute COVID-19 Syndrome studies →National Institute of Allergy and Infectious Diseases (NIAID) is the lead sponsor of 2,446 studies on the registry; 179 are open to participants now.
Of its 405 completed or terminated interventional studies of FDA-regulated products, 302 (75%) have results posted.
Counted across the registry records on this site, refreshed daily.
Go through the criteria one by one — yes, no or not sure — and take the list to your doctor or the study team. Kept in this browser only.
History of SARS CoV 2 infection shown by (1) a positive nucleic acid amplification test (NAAT) or antigen test, OR (2) meeting clinical criteria* AND an epidemiologic link** to a confirmed case.
*Clinical criteria is defined as either (1) acute onset of fever AND cough; OR (2) acute altered/loss of taste or smell + one additional symptom including: fever, cough, general weakness/fatigue, headache, myalgia, sore throat, coryza, dyspnea, nausea, diarrhea, or anorexia; OR (3) three or more symptoms, including fever, cough, general weakness/fatigue, headache, myalgia, sore throat, coryza, dyspnea, nausea, diarrhea, or anorexia.
Clinical evidence of Long COVID* and Long COVID symptoms that cannot be attributed to another cause upon investigator review of medical history and workup participant received prior to study entry.
*Participants must meet the 2024 National Academies of Sciences, Engineering, and Medicine definition for Long COVID.
Has new fatigue*, ** that began either during or in the six months following the onset of the qualifying SARS CoV 2 infection or COVID 19 illness (see inclusion Criterion #3):
*New fatigue symptoms can fluctuate but the total duration of fatigue must be at least 3 months at time of randomization and fatigue must be present for more days than not in the 30 days prior to randomization.
**For this trial, fatigue is defined as having physical fatigue and/or cognitive fatigue (e.g., has trouble with memory, focus/attention, or decision-making, or is slow to process information, and is sometimes referred to as having "brain fog"). Fatigue is a persistent state of physical and/or cognitive exhaustion that is not substantially alleviated by sleep or rest, and that interferes with normal functioning, is often profound, and is not the result of ongoing or unusual excessive exertion.
Has at least one new or worsening symptom*, ** that began either during or in the six months following the onset of the qualifying SARS CoV 2 infection or COVID 19 illness:
*List of qualifying symptoms include: systemic symptoms (chills, Post-Exertional Malaise [PEM]); neurological symptoms (headache, dysautonomia/ Postural Orthostatic Tachycardia Syndrome [POTS], dizziness, unsteadiness, or neuropathy); sleep disturbance resulting in unrefreshing sleep; cardiopulmonary symptoms (chest pain, palpitations, shortness of breath, cough, fainting spells); musculoskeletal symptoms (muscle pain/aches, neck pain, back pain, joint pain); or gastrointestinal symptoms (nausea, diarrhea).
**While the qualifying symptom(s) may fluctuate, the total duration of at least one qualifying symptom must be at least 3 months at time of randomization. In addition, that symptom must be present for more days than not in the 30 days prior to randomization.
Able to understand and agree to comply with all planned study procedures and be available for all study visits.
*Participants still may enroll if they decline genetic testing or if they are unable or unwilling to complete blood draw(s) for biomarkers. An initial blood draw for baseline clinical laboratory assessments is required to be completed prior to randomization.
Participants of * must agree to use highly effective ** or practice true abstinence*** throughout the study (Visit 08).
*Persons of childbearing potential is defined as post-menarchal biological females who have not reached menopause or undergone surgical sterilization. Menopause is defined as having no menses for at least 12 months without an alternative medical cause for amenorrhea.
**Highly effective contraception includes hormonal contraception (oral, implant, injection, transdermal patch, vaginal ring), intrauterine device (IUD), bilateral tubal ligation, or partner vasectomy.
***True abstinence is defined as no heterosexual vaginal/penile intercourse at any time during the study
Participants capable of fathering a child* and having sex with women of childbearing potential must agree to use contraception (i.e., condoms) throughout the study (Visit 08).
*Persons capable of fathering a child are biological males who are post-pubertal and not permanently sterile by bilateral orchidectomy or vasectomy
Exclusion Criteria:
Has recent active (received chemotherapy or radiotherapy in the 12 months prior to randomization) or active malignancy at randomization*.
Began taking a new medication*, supplement, or vitamin or changed doses of a medication, supplement, or vitamin the 14 days prior to randomization.
*Topical and intranasal (non-opioid) medications are not exclusionary.
Diagnosed in the 3 months prior to randomization with a new medical condition*, other than Long COVID, causing new or worsening fatigue that is unresolved at time of randomization.
*Medical conditions that could cause new or worsening fatigue include but are not limited to iron deficiency with or without severe anemia, hypothyroidism, infectious mononucleosis (Epstein-Barr Virus or cytomegalovirus infection), celiac disease, type 1 diabetes mellitus, acute leukemia or hematologic malignancy, adrenal insufficiency, cardiac disease (e.g. myocarditis, arrythmia, or cardiomyopathy), metabolic disease, renal disease, or a primary sleep disorders (e.g. obstructive sleep apnea, restless legs syndrome, narcolepsy, or parasomnia).
Has a mental health condition defined by history of one or more of the following:
a. History of prior suicide attempt. b. Hospitalized in the 6 months prior to randomization for mental health symptoms or worsening of a known mental health condition.
c. Has moderate-risk or high-risk score on C SSRS at Visit 01A, as applicable. d. Has a diagnosis of severe conduct disorder*that, in the site investigator's judgment, may pose a safety risk or interfere with the ability to adequately assess clinical trial endpoints.
*The American Psychiatric Association defines conduct disorder as a repetitive and persistent pattern of behavior in which the basic rights of others or major age-appropriate societal norms or rules are violated (e.g., history of recurrent aggressive behavior toward people or animals, and/or serious violations of rules or laws like running away, possessing or using weapons, vandalism). If the site Investigator is unsure if a participant has a diagnosis of severe conduct disorder, they may refer to the criteria.
Has any medical condition*, ** that, in the site investigator's judgment, pose a safety risk or interfere with the ability to adequately assess clinical trial endpoints.
Medical conditions include but are not limited to severe esophagitis or a condition that precludes participant from taking study product; an active unstable or progressive major psychiatric or neurologic condition, including severe developmental disabilities, new or untreated psychosis or schizophrenia, new or untreated bipolar I disorder; and acute opioid withdrawal disorder to include participants maintained on opiate agonists (methadone) or partial agonists (buprenorphine) and those who has failed a naloxone challenge test.
Underlined terms in the criteria open these too. Explained by clinicaltrials.gg, not part of the registry record. The study team decides who can take part.
Before you join, the study team explains what taking part involves — its purpose, what happens, the risks and possible benefits — and answers your questions, so you can decide freely. Consent is usually recorded on a form (the informed consent form, ICF) signed by you or, where the law allows, by someone legally authorised to decide for you.
You can keep asking questions during the study, you are told of new information that matters, and you can choose to leave at any time.
Able to become pregnant: from the first period until menopause, unless permanently unable to through surgery (removal of the womb, or of both ovaries or both fallopian tubes).
Criteria for people of childbearing potential usually ask for a negative pregnancy test and for contraception during the study and for a time after it.
Ways of preventing pregnancy. “Highly effective” methods fail less than 1% of the time a year when used correctly — for example an IUD or an implant.
Criteria usually say which methods count and how long to keep using them after the last dose, sometimes for male participants too. Some studies accept a partner’s vasectomy if it was confirmed successful and that person is the participant’s only sexual partner.
An allergy, or another reaction of the immune system, to a substance. “Hypersensitivity to the study drug” means a known allergic reaction to it — not every side effect a medicine can have.
A score of how well the liver works in people with liver disease such as cirrhosis: class A is mild, B moderate and C severe.
GFR (glomerular filtration rate) is how much blood the kidneys filter each minute. It is usually estimated from a blood test — eGFR, by formulas such as CKD-EPI or MDRD — and some studies ask for it to be measured directly instead. Usually given in mL/min/1.73 m².
Check the method, the units and the minimum the study states. A value of 90 or above is in the normal-or-high range, but kidney damage can show in other tests too.
Hepatitis B is a virus that infects the liver. These are separate tests: HBsAg positive usually means a current infection (a recent vaccination can briefly cause it too); total anti-HBc (HBcAb) positive means an infection now or in the past; HBV DNA measures how much virus is in the blood.
Some studies accept a past infection if HBV DNA is undetectable, sometimes with antiviral medicine during the study. Check what this study allows.
Hepatitis C is a virus that infects the liver. An HCV antibody test can stay positive after an infection has cleared (and is occasionally positive without one); an HCV RNA test shows whether the virus is there now.
After treatment, hepatitis C counts as cured when HCV RNA is still undetectable 12 weeks or more after the treatment ended. Studies often accept people cured this way.
The human immunodeficiency virus, which weakens the immune system.
Many studies now accept people whose HIV is controlled on treatment, judged by the viral load and the CD4 count. Check the limits this study sets.
Malignancy means cancer. Criteria about another or earlier malignancy ask whether you have had a different cancer, usually within a set number of years.
Some are commonly allowed, such as treated skin cancers other than melanoma and early cancers removed completely — check the exceptions this study lists.
Judged by the study doctor to matter for your health or for the study. It is a doctor’s decision, so ask the study team if you are unsure whether something counts.
The American Psychiatric Association’s manual of mental health diagnoses. DSM-5 (2013, revised as DSM-5-TR in 2022) replaced DSM-IV, and some studies still name the older edition. “Meets DSM criteria for …” means diagnosed by that edition’s diagnostic criteria, usually by a clinician in an interview.
Informed consent
Before you join, the study team explains what taking part involves — its purpose, what happens, the risks and possible benefits — and answers your questions, so you can decide freely. Consent is usually recorded on a form (the informed consent form, ICF) signed by you or, where the law allows, by someone legally authorised to decide for you.
You can keep asking questions during the study, you are told of new information that matters, and you can choose to leave at any time.
Explained by clinicaltrials.gg, not part of the registry record. The study team decides who can take part.
Childbearing potential
Able to become pregnant: from the first period until menopause, unless permanently unable to through surgery (removal of the womb, or of both ovaries or both fallopian tubes).
Criteria for people of childbearing potential usually ask for a negative pregnancy test and for contraception during the study and for a time after it.
Explained by clinicaltrials.gg, not part of the registry record. The study team decides who can take part.
Contraception
Ways of preventing pregnancy. “Highly effective” methods fail less than 1% of the time a year when used correctly — for example an IUD or an implant.
Criteria usually say which methods count and how long to keep using them after the last dose, sometimes for male participants too. Some studies accept a partner’s vasectomy if it was confirmed successful and that person is the participant’s only sexual partner.
Explained by clinicaltrials.gg, not part of the registry record. The study team decides who can take part.
Hypersensitivity
An allergy, or another reaction of the immune system, to a substance. “Hypersensitivity to the study drug” means a known allergic reaction to it — not every side effect a medicine can have.
Explained by clinicaltrials.gg, not part of the registry record. The study team decides who can take part.
Child-Pugh class
A score of how well the liver works in people with liver disease such as cirrhosis: class A is mild, B moderate and C severe.
Explained by clinicaltrials.gg, not part of the registry record. The study team decides who can take part.
GFR and eGFR (kidney filtering)
GFR (glomerular filtration rate) is how much blood the kidneys filter each minute. It is usually estimated from a blood test — eGFR, by formulas such as CKD-EPI or MDRD — and some studies ask for it to be measured directly instead. Usually given in mL/min/1.73 m².
Check the method, the units and the minimum the study states. A value of 90 or above is in the normal-or-high range, but kidney damage can show in other tests too.
Explained by clinicaltrials.gg, not part of the registry record. The study team decides who can take part.
Hepatitis B tests
Hepatitis B is a virus that infects the liver. These are separate tests: HBsAg positive usually means a current infection (a recent vaccination can briefly cause it too); total anti-HBc (HBcAb) positive means an infection now or in the past; HBV DNA measures how much virus is in the blood.
Some studies accept a past infection if HBV DNA is undetectable, sometimes with antiviral medicine during the study. Check what this study allows.
Explained by clinicaltrials.gg, not part of the registry record. The study team decides who can take part.
Hepatitis C tests
Hepatitis C is a virus that infects the liver. An HCV antibody test can stay positive after an infection has cleared (and is occasionally positive without one); an HCV RNA test shows whether the virus is there now.
After treatment, hepatitis C counts as cured when HCV RNA is still undetectable 12 weeks or more after the treatment ended. Studies often accept people cured this way.
Explained by clinicaltrials.gg, not part of the registry record. The study team decides who can take part.
HIV
The human immunodeficiency virus, which weakens the immune system.
Many studies now accept people whose HIV is controlled on treatment, judged by the viral load and the CD4 count. Check the limits this study sets.
Explained by clinicaltrials.gg, not part of the registry record. The study team decides who can take part.
Cancer (malignancy)
Malignancy means cancer. Criteria about another or earlier malignancy ask whether you have had a different cancer, usually within a set number of years.
Some are commonly allowed, such as treated skin cancers other than melanoma and early cancers removed completely — check the exceptions this study lists.
Explained by clinicaltrials.gg, not part of the registry record. The study team decides who can take part.
Clinically significant
Judged by the study doctor to matter for your health or for the study. It is a doctor’s decision, so ask the study team if you are unsure whether something counts.
Explained by clinicaltrials.gg, not part of the registry record. The study team decides who can take part.
DSM diagnostic criteria
The American Psychiatric Association’s manual of mental health diagnoses. DSM-5 (2013, revised as DSM-5-TR in 2022) replaced DSM-IV, and some studies still name the older edition. “Meets DSM criteria for …” means diagnosed by that edition’s diagnostic criteria, usually by a clinician in an interview.
Explained by clinicaltrials.gg, not part of the registry record. The study team decides who can take part.
Participants will receive a low-dose naltrexone (LDN) capsule that will be administered orally once daily for 16 weeks. LDN will be initiated at 1.5 mg daily and titrated weekly to a maximum tolerated dose of up to 4.5 mg daily. N=650
Drug: naltrexone
Participants will receive a matching placebo capsule that will be administered orally once daily for 16 weeks. The placebo arm will follow the same dosing schedule and titration scheme as the LDN arm. N=650
Other: Placebo
Opioid receptor antagonist used to treat opioid and alcohol use disorders in adults. Formulated as naltrexone hydrochloride, a white, crystalline compound freely soluble in water.
Matching placebo capsule that is visually identical to the active study product and is administered orally once daily according to the same dosing schedule and titration scheme for 16 weeks.
Change from baseline in Pediatric Quality of Life - Multidimensional Fatigue Scale (PedsQL-MFS) total score.
The Pediatric Quality of Life - Multidimensional Fatigue Scale (PedsQL-MFS) contains 18 Likert-type items and is scored from 0 to 100; higher scores represent lower levels of fatigue.
Time frame: Baseline to 16 weeks after randomization
Change from baseline Delis-Kaplan Executive Function System (D-KEFS) Category Fluency t-score
The D-KEFS Verbal Fluency Category Fluency condition measures verbal fluency and executive function. Participants generate as many words as possible beginning with a specified letter within a fixed time. Performance score is scored by the number of correct words and interpreted using age-appropriate normative data. This outcome applies to English-speaking participants aged 8 to 25 years.
Time frame: Baseline to 16 weeks after randomization
Change from baseline Delis-Kaplan Executive Function System (D-KEFS) Letter Fluency t-score
The D-KEFS Verbal Fluency Letter Fluency condition measures verbal fluency and executive function. Participants generate as many words as possible beginning with a specified letter within a fixed time. Performance score is scored by the number of correct words and interpreted using age-appropriate normative data. This outcome applies to English-speaking participants aged 8 to 25 years.
Time frame: Baseline to 16 weeks after randomization
Change from baseline in Behavior Rating Inventory of Executive Function-Second Edition (BRIEF-2) Global Executive Composite t-score
The BRIEF-2 is a standardized questionnaire assessing executive function and self-regulation in participants aged 6 to 17 years. Scores are interpreted using age- and sex-appropriate normative data. Higher scores indicate greater impairment in executive functioning.
Time frame: Baseline to 16 weeks after randomization
Change from baseline in Behavior Rating Inventory of Executive Function-Second Edition (BRIEF-2A) Global Executive Composite t-score
The BRIEF-2A is a standardized 75-item self-report assessment of executive functioning in participants aged 18 years and older. Scores are interpreted using age- and sex-appropriate normative data. Higher scores indicate greater impairment in executive functioning.
Time frame: Baseline to 16 weeks after randomization
Change from baseline in Conners Continuous Performance Test-Third Edition (CPT-3) Detectability t-score.
The CPT-3 is a computerized assessment of sustained attention and response control for participants aged 8 years and older. Performance is automatically recorded and interpreted using age-appropriate normative data.
Time frame: Baseline to 16 weeks after randomization
Change from baseline in Conners Continuous Performance Test-Third Edition (CPT-3) Hit Reaction Time t-score
The CPT-3 is a computerized assessment of sustained attention and response control for participants aged 8 years and older. Performance is automatically recorded and interpreted using age-appropriate normative data.
Time frame: Baseline to 16 weeks after randomization
Change from baseline in Connors Kiddie Continuous Performance Test (K-CPT-2) Detectability t-score.
The K-CPT-2 Computerized assessment of sustained attention and response control for participants aged 6 to 7 years. Performance is automatically recorded and interpreted using age-appropriate normative data.
Time frame: Baseline to 16 weeks after randomization
Change from baseline in Connors Kiddie Continuous Performance Test (K-CPT-2) Hit Reaction Time t-score
The K-CPT-2 Computerized assessment of sustained attention and response control for participants aged 6 to 7 years. Performance is automatically recorded and interpreted using age-appropriate normative data.
Time frame: Baseline to 16 weeks after randomization
Change from baseline in Developmental Neuropsychological Assessment (NEPSY-II) Semantic Word Generation Scaled score.
The NEPSY-II Word Generation subtest measures verbal fluency and executive function. Participants generate words within semantic category during 60-second time limit. Performance is scored by the number of correct words\[TS3.1\] and interpreted using age-appropriate normative data. This outcome applies to English-speaking participants aged 6 to 7 years.
Time frame: Baseline to 16 weeks after randomization
Change from baseline in Digit Span-Wechsler Intelligence Scale for Children-Fifth Edition (WISC-V) t-score.
The WISC-V Digit Span subtest assesses attention and working memory in participants aged 6 to 15 years. Raw scores are based on Digit Span Forward, Backward, and Sequencing tasks and are interpreted using age-appropriate normative data.
Time frame: Baseline to 16 weeks after randomization
Change from baseline in Digit Span-Wechsler Intelligence Scale for Children-Fourth Edition (WISC-IV) t-score.
The WISC-IV Digit Span subtest assesses attention and working memory in participants aged 16 years and older. Raw scores are based on Digit Span Forward, Backward, and Sequencing tasks and are interpreted using age-appropriate normative data.
Time frame: Baseline to 16 weeks after randomization
Change from baseline in Functional Disability Inventory (FDI) total score.
The Functional Disability Inventory (FDI) contains 15 items rated from 0 ('no trouble') to 4 ('impossible'). Total scores range from 0 to 60. Higher scores represent greater functional disability and more impairment in daily functioning.
Time frame: Baseline to 16 weeks after randomization
Change from baseline in Patient Global Impression of Severity (PGI-S)
The Patient Global Impression of Severity (PGI-S) is a single-item questionnaire rated on a 5-point Likert scale from 1 ('None') to 5 ('Very severe'). Higher scores reflect greater perceived illness or symptom severity.
Time frame: Baseline to 16 weeks after randomization
Change from baseline in Patient-Reported Outcomes Measurement Information System (PROMIS) Adult Pain Intensity Scale t-score in participants aged 18 to 25 years.
The Patient-Reported Outcomes Measurement Information System (PROMIS) Pain Intensity Scale asks about pain over the past 7 days. Items are rated on a 5-point scale from 1 ('not at all') to 5 ('very much'). Results are reported as T-scores. Higher scores representing greater pain intensity.
Time frame: Baseline to 16 weeks after randomization
Change from baseline in Patient-Reported Outcomes Measurement Information System (PROMIS) Adult Pain Interference Scale t-score in participants aged 18 to 25 years.
The Patient-Reported Outcomes Measurement Information System (PROMIS) Pain Intensity Scale asks how pain affects activities, mood, and social participation over the past 7 days. Items are rated on a 5-point scale from 1 ('not at all') to 5 ('very much'). Results are reported as T-scores. Higher scores representing greater pain interference.
Time frame: Baseline to 16 weeks after randomization
Change from baseline in Patient-Reported Outcomes Measurement Information System (PROMIS) Parent-Proxy Pain Intensity Scale t-score in participants aged 6 to 7 years.
The Patient-Reported Outcomes Measurement Information System (PROMIS) Pain Intensity scale asks about pain over the past 7 days. Items are rated on a 5-point scale from 1 ('not at all') to 5 ('very much'). Results are reported as T-scores, with higher scores representing greater pain intensity.
Time frame: Baseline to 16 weeks after randomization
Change from baseline in Patient-Reported Outcomes Measurement Information System (PROMIS) Parent-Proxy Pain Interference Scale t-score in participants aged 6 to 7 years.
The Patient-Reported Outcomes Measurement Information System (PROMIS) Parent-Proxy Pain Interference Scale asks how pain affects activities, mood, and social participation over the past 7 days. Items are rated on a 5-point scale from 1('not at all') to 5('very much'). Results are reported as T-scores. Higher scores representing greater pain interference.
Time frame: Baseline to 16 weeks after randomization
Change from baseline in Patient-Reported Outcomes Measurement Information System (PROMIS) Pediatric Pain Intensity Scale t-score in participants aged 8 to 17 years.
The Patient-Reported Outcomes Measurement Information System (PROMIS) Pediatric Pain Intensity Scale asks about pain over the past 7 days. Items are rated on a 5-point scale from 1 ('not at all') to 5 ('very much'). Results are reported as T-scores. Higher scores representing greater pain intensity.
Time frame: Baseline to 16 weeks after randomization
Change from baseline in Patient-Reported Outcomes Measurement Information System (PROMIS) Pediatric Pain Interference Scale t-score in participants aged 8 to 17 years.
The Patient-Reported Outcomes Measurement Information System (PROMIS) Pediatric Pain Interference scale asks how pain affects activities, mood, and social participation over the past 7 days. Items are rated on a 5-point scale from 1 ('not at all') to 5 ('very much'). Results are reported as T-scores. Higher scores representing greater pain interference.
Time frame: Baseline to 16 weeks after randomization
Change from baseline in Pediatric Quality of Life (PedsQL) Generic Core Scales Short Form 15 total score.
The PedsQL Generic Core Scales Short Form 15 contains 15 Likert-type items across physical, emotional, social, and school functioning and is scored from 0 to 100. Higher scores represent better quality of life.
Time frame: Baseline to 16 weeks after randomization
Change from baseline in Pediatric Quality of Life - Multidimensional Fatigue Scale (PedsQL-MFS) subscale scores.
The Pediatric Quality of Life - Multidimensional Fatigue Scale (PedsQL-MFS) contains 18 Likert-type items and includes general fatigue, sleep/rest fatigue, and cognitive fatigue subscales. Scores are reported on a 0 to 100 scale. Higher scores represent lower levels of fatigue.
Time frame: Baseline to 16 weeks after randomization
Change from baseline in Pediatric Quality of Life - Multidimensional Fatigue Scale (PedsQL-MFS) total score in participants aged 12 to 17 years.
The Pediatric Quality of Life - Multidimensional Fatigue Scale (PedsQL-MFS) contains 18 Likert-type items and is scored from 0 to 100; higher scores represent lower levels of fatigue.
Time frame: Baseline to 16 weeks after randomization
Change from baseline in Pediatric Quality of Life - Multidimensional Fatigue Scale (PedsQL-MFS) total score in participants aged 18 to 25 years.
The Pediatric Quality of Life - Multidimensional Fatigue Scale (PedsQL-MFS) contains 18 Likert-type items and is scored from 0 to 100; higher scores represent lower levels of fatigue.
Time frame: Baseline to 16 weeks after randomization
Change from baseline in Pediatric Quality of Life - Multidimensional Fatigue Scale (PedsQL-MFS) total score in participants aged 6 to 11 years.
The Pediatric Quality of Life - Multidimensional Fatigue Scale (PedsQL-MFS) contains 18 Likert-type items and is scored from 0 to 100; higher scores represent lower levels of fatigue.
Time frame: Baseline to 16 weeks after randomization
Change in Pediatric Quality of Life Multidimensional Fatigue Scale (PedsQL-MFS) total score from 16 to 26 weeks after randomization.
The Pediatric Quality of Life Multidimensional Fatigue Scale (PedsQL-MFS) contains 18 Likert-type items and is scored from 0 to 100. Higher scores represent lower levels of fatigue.
Time frame: 16 to 26 weeks after randomization
Incidence of new infections.
New infections will be summarized by frequency, percentage, and incidence rate. Severity and relatedness will also be summarized as applicable.
Time frame: First administration of study product through 6 months after randomization
Incidence of new-onset chronic medical conditions (NOCMCs).
NOCMCs will be assessed by number, severity, and relatedness and summarized by frequency, percentage, and incidence rate.
Time frame: First administration of study product through 6 months after randomization
Incidence of solicited adverse events (AEs).
Solicited AEs will be assessed by number, severity, and relatedness according to the DAIDS table for Grading the Severity of Adult and Pediatric Adverse Event, version 2.1.
Time frame: First administration of study product through 8 weeks after randomization
Incidence of treatment emergent serious adverse events (SAEs).
Treatment-emergent SAEs will be assessed by number, severity, and relatedness and summarized by frequency, percentage, and incidence rate.
Time frame: First administration of study product through 6 months after randomization
Incidence of treatment emergent unsolicited adverse events (AEs).
Treatment-emergent unsolicited AEs will be assessed by number, severity, and relatedness according to the DAIDS table for Grading the Severity of Adult and Pediatric Adverse Event, version 2.1.
Time frame: First administration of study product through 16 weeks after randomization
Incidence of treatment-emergent medically attended adverse events (MAAEs).
Treatment-emergent MAAEs will be assessed by number, severity, and relatedness and summarized by frequency, percentage, and incidence rate.
Time frame: First administration of study product through 6 months after randomization
Patient Global Impression of Change (PGI-C) at 16 weeks after randomization
The PGI-C is a 7-point self-report scale ranging from 'very much improved'\[TS4.1\] to 'very much worse'\[TS5.1\] and measures overall improvement from treatment.
Time frame: 16 weeks after randomization
Plan to share: No
No publications or documents are linked to this record.
From the registry record's own update history. This site started tracking changes on Sep 25, 2026; for anything earlier, see the record history on ClinicalTrials.gov ↗
This study is not yet recruiting, as verified in Oct 2026. You cannot join it, but the record below documents what was studied.
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Studies of the drug tested here: Naltrexone
Post-Acute COVID-19 Syndrome →
National Institute of Allergy and Infectious Diseases (NIAID) →