Summary
| Direction in Long COVID | ↑ Elevated — higher than in the comparison group |
|---|---|
| Category | Inflammatory |
| Also described as | CXCL8 |
| Compared against | HC (healthy controls) |
| Associated symptoms | Neutrophil chemotaxis |
| Test type | Blood test (serum / plasma / whole blood) |
| LOINC code | 26998-9 |
| Source | Thomas et al. 2024 — doi:10.1007/s40291-024-00731-z |
| Condition atlas | Long COVID Biomarker Atlas |
Other conditions where Interleukin-8 (IL-8 / CXCL8) is reported
- Interleukin-8 (IL-8 / CXCL8) in Gulf War Illness — ↑ elevated vs HGV
- Interleukin-8 (IL-8 / CXCL8) in ME/CFS — ↕ inconsistent vs HC
- IL-8 in PACVS — ↑ elevated vs HC
See the cross-condition hub: Interleukin-8 (IL-8 / CXCL8) across conditions.
Trials, interventions and tests
Commercial test availability
Interleukin-8 (IL-8) — specialty laboratory test.
Links are for reference only; availability, specimen requirements and coverage vary by location.
Related Inflammatory markers in Long COVID
- Transforming Growth Factor-β (TGF-β) ↑
- Interleukin-10 (IL-10) ↕
- Pro-inflammatory cytokines (composite) ↓
- Ferritin ↕
- Cystatin D (CST5) ↑
- Serum Amyloid A (SAA) ↑
- CCL4 (MIP-1β) ↑
- Flt-1 / sVEGFR-1 ↑
Full list: Long COVID Biomarker Atlas.
Frequently asked questions
Is Interleukin-8 (IL-8) high or low in Long COVID?
Elevated. Studies summarised in the OSMF atlas report higher Interleukin-8 (IL-8) in Long COVID than in healthy controls. Source: Thomas et al. 2024.
What symptoms is Interleukin-8 (IL-8) associated with in Long COVID?
The cited literature associates this marker with Neutrophil chemotaxis. These are population-level associations and do not mean the marker causes the symptoms.
Which test measures Interleukin-8 (IL-8)?
It is measured as a blood test (serum / plasma / whole blood). The standard laboratory code is LOINC 26998-9. Commercial laboratories such as Quest Diagnostics, LabCorp list an orderable assay.
Is one abnormal Interleukin-8 (IL-8) result diagnostic of Long COVID?
No. No single biomarker is diagnostic of Long COVID. Interleukin-8 (IL-8) findings come from group comparisons, overlap considerably between patients and controls, and vary with study design, timing and comparison group. A result should be interpreted by a clinician alongside symptoms, history and other tests.
Is Interleukin-8 (IL-8) specific to Long COVID?
No. The same marker is also reported in Gulf War Illness, ME/CFS, PACVS in this atlas, so it reflects shared biology (for example inflammation or vascular stress) rather than a condition-specific signature.
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Last reviewed: 2026-06-29 · Page generated from long-covid.json · Browse: Long COVID atlas · Biomarker Index · All marker pages
Disclaimer: This page is an educational synthesis of published, peer-reviewed research and is not medical advice. Biomarker findings vary across studies with case definitions, comparison groups, timing and assay methods. Direction of change reflects the predominant finding in the cited source and does not establish a diagnostic threshold. Discuss any test result with a qualified clinician.