Fatigue Severity Scale
The Fatigue Severity Scale is a brief self-report of fatigue impact. This page is for clinics. It is not a diagnosis of a sleep or medical disorder and not a public test.
Overview
What is the FSS?
The FSS asks about fatigue severity and interference. Fatigue has many medical, psychiatric, and sleep-related causes, so a score is not a diagnosis. It is also listed among blood-testing-adjacent symptom measures because fatigue is reviewed before laboratory work, not because it orders tests.
Development and clinical use
Krupp and colleagues published the FSS in 1989 as a fatigue-severity instrument, first applied in multiple sclerosis and systemic lupus erythematosus.
- Catalogue status
- Educational entry
- Production scoring
- Not independently verified
- Mode
- self-report
- Typical use
- Clinician-reviewed intake
- Clinical role
- Fatigue-impact screening support
Administration
A focused client experience
The respondent rates all nine statements from 1 to 7 for the past week. Every rating is required.
- One question at a time with visible progress
- Large keyboard-operable response choices
- Previous, next, and answer-review steps
- Clear confirmation that results go to the clinic
The illustration shows layout only. It does not reproduce FSS item wording.
Report showcase
Designed to make evidence easy to review
The downloadable synthetic example illustrates report layout using invented response patterns, without patient data or instrument questions.
- Named instrument, version, and provenance
- Item-level response pattern without source wording
- Methodology, references, and clinical boundary
- Responsible clinician review rather than automated conclusions
Clinician review required
Methodology
Understand the measure and its scoring conventions
Lirena adds the nine ratings for a total from 9 to 63. Less than 36 covers 9 to 35. 36 or more covers 36 to 63. The result is the published band label for clinician review. It does not diagnose a fatigue disorder.
References
- Original FSS paperKrupp LB et al. The fatigue severity scale. Application to patients with multiple sclerosis and systemic lupus erythematosus. Arch Neurol. 1989;46(10):1121-1123.
Questions
What clinics ask before they evaluate the FSS
These answers stay inside educational catalogue scope. They do not replace official manuals or clinician judgement.
Does FSS diagnose chronic fatigue or sleep apnoea?
No. It is a fatigue-impact self-report. Diagnosis remains a clinician task.
Can I complete FSS here?
No. This page does not collect answers or recommend blood tests.
How is FSS used on Lirena?
As a sleep and general-intake self-report. Clinicians review the result with history rather than treating a score as a diagnosis.
Does FSS determine which blood tests to order?
No. Symptom questionnaires on Lirena do not order or select laboratory tests.