Social Security Ruling 99-2p (Evaluating Cases Involving CFS)
EFFECTIVE/PUBLICATION DATE: 4/30/99
SSR 99-2p: POLICY INTERPRETATION RULING
TITLES II AND XVI: EVALUATING CASES
INVOLVING CHRONIC FATIGUE SYNDROME (CFS)
To restate and clarify the policies of the Social Security Administration for developing and evaluating title II and title XVI
claims for disability on the basis of Chronic Fatigue Syndrome (CFS), also frequently known as Chronic Fatigue and
Immune Dysfunction Syndrome.
Sections 216(i), 223(d), 223(f), 1614(a)(3) and 1614(a)(4) of the Social Security Act, as amended; Regulations No. 4,
subpart P, sections 404.1505, 404.1508-404.1513, 404.1520, 404.1520a, 404.1521, 404.1523, 404.1526-404.1529,
404.1560-404.1569a and 404.1593-404.1594; and Regulations No. 16, subpart I, sections 416.905, 416.906,
416.908-416.913, 416.920, 416.920a, 416.921, 416.923, 416.924, 416.924b, 416.924c, 416.926, 416.926a,
416.927-416.929, 416.960-416.969a, 416.987, 416.993, 416.994, and 416.994a.
CFS is a systemic disorder consisting of a complex of symptoms that may vary in incidence, duration, and severity. The current case criteria for CFS, developed by an international group convened by the Centers for Disease Control and Prevention (CDC) as an identification tool and research definition, include a requirement for four or more of a
specified list of symptoms. These constitute a patient's complaints as reported to a provider of treatment.
However, the Social Security Act (the Act) and our implementing regulations require that an individual establish disability based on the existence of a medically determinable impairment; i.e., one that can be shown by medical evidence, consisting of medical signs, symptoms and laboratory findings. Disability may not be established on the
basis of an individual s statement of symptoms alone.
This Ruling explains that CFS, when accompanied by appropriate medical signs or laboratory findings, is a medically
determinable impairment that can be the basis for a finding of "disability." It also provides guidance for the evaluation of
claims involving CFS.
CFS constitutes a medically determinable impairment when it is accompanied by medical signs or laboratory findings,
as discussed below. CFS may be a disabling impairment.
Definition of CFS
CFS is a systemic disorder consisting of a complex of symptoms that may vary in incidence, duration, and severity. It
is characterized in part by prolonged fatigue that lasts 6 months or more and that results in substantial reduction in
previous levels of occupational, educational, social, or personal activities. In accordance with criteria established by
the CDC, a physician should make a diagnosis of CFS "only after alternative medical and psychiatric causes of
chronic fatiguing illness have been excluded" (Annals of Internal Medicine, 121:953-9, 1994). CFS has been
diagnosed in children, particularly adolescents, as well as in adults.
Under the CDC definition, the hallmark of CFS is the presence of clinically evaluated, persistent or relapsing chronic
fatigue that is of new or definite onset (i.e., has not been lifelong), cannot be explained by another physical or mental
disorder, is not the result of ongoing exertion, is not substantially alleviated by rest, and results in substantial reduction
in previous levels of occupational, educational, social, or personal activities. Additionally, the current CDC definition of
CFS requires the concurrence of 4 or more of the following symptoms, all of which must have persisted or recurred
during 6 or more consecutive months of illness and must not have pre-dated the fatigue:
Self-reported impairment in short-term memory or concentration severe enough to cause substantial reduction
in previous levels of occupational, educational, social, or personal activities;
Tender cervical or axillary lymph nodes;
Multi-joint pain without joint swelling or redness;
Headaches of a new type, pattern, or severity;
Unrefreshing sleep; and
Postexertional malaise lasting more than 24 hours.
Within these parameters, an individual with CFS can also exhibit a wide range of other manifestations, such as
muscle weakness, swollen underarm (axillary) glands, sleep disturbances, visual difficulties (trouble focusing or
severe photosensitivity), orthostatic intolerance (e.g., lightheadedness or increased fatigue with prolonged standing),
other neurocognitive problems (e.g., difficulty comprehending and processing information), fainting, dizziness, and
mental problems (e.g., depression, irritability, anxiety).
Requirement for a Medically Determinable Impairment
Sections 216(i) and 1614(a)(3) of the Act define "disability" as the inability to engage in any substantial gainful activity
(SGA) by reason of any medically determinable physical or mental impairment (or combination of impairments) which
can be expected to result in death or which has lasted or can be expected to last for a continuous period of not less
than 12 months. Sections 223(d)(3) and 1614(a)(3)(D) of the Act, and 20 CFR 404.1508 and 416.908 require that an
impairment result from anatomical, physiological, or psychological abnormalities that can be shown by medically
acceptable clinical and laboratory diagnostic techniques. The Act and regulations further require that an impairment be
established by medical evidence that consists of signs, symptoms, and laboratory findings, and not only by an
individual's statement of symptoms.
Under the CDC definition, the diagnosis of CFS can be made based on an individual s reported symptoms alone once
other possible causes for the symptoms have been ruled out. However, the foregoing statutory and regulatory
provisions require that, for evaluation of claims of disability under the Act, there must also be medical signs or
laboratory findings before the existence of a medically determinable impairment may be established.
Establishing the Existence of a Medically Determinable Impairment
The following medical signs and laboratory findings establish the existence of a medically determinable impairment in
individuals who have CFS. Although no specific etiology or pathology has yet been established for CFS, many
research initiatives continue, and some progress has been made in ameliorating symptoms in selected individuals.
With continuing scientific research, new medical evidence may emerge that will further clarify the nature of CFS and
provide greater specificity regarding the clinical and laboratory diagnostic techniques that should be used to document
Because of this, the medical criteria discussed below are only examples of signs and laboratory findings that will
establish the existence of a medically determinable impairment; they are not all-inclusive. As progress is made in
medical research into CFS, additional signs and laboratory findings may also be found that can be used to establish
that individuals with CFS have a medically determinable impairment. The existence of CFS may be documented with
medical signs or laboratory findings other than those listed below, provided that such documentation is consistent with
medically accepted clinical practice and is consistent with the other evidence in the case record.
Examples of medical signs that establish the existence of a medically determinable
For purposes of Social Security disability evaluation, one or more of the following medical signs clinically documented
over a period of at least 6 consecutive months establishes the existence of a medically determinable impairment for
individuals with CFS:
Palpably swollen or tender lymph nodes on physical examination;
Persistent, reproducible muscle tenderness on repeated examinations, including the presence of positive tender
Any other medical signs that are consistent with medically accepted clinical practice and are consistent with the
other evidence in the case record.
Examples of laboratory findings that establish the existence of a medically
At this time, there are no specific laboratory findings that are widely accepted as being associated with CFS. However,
the absence of a definitive test does not preclude reliance upon certain laboratory findings to establish the existence of
a medically determinable impairment in persons with CFS. Therefore, the following laboratory findings establish the
existence of a medically determinable impairment in individuals with CFS:
An elevated antibody titer to Epstein-Barr virus (EBV) capsid antigen equal to or greater than 1:5120, or early
antigen equal to or greater than 1:640;
An abnormal magnetic resonance imaging (MRI) brain scan;
Neurally mediated hypotension as shown by tilt table testing or another clinically accepted form of testing; or,
Any other laboratory findings that are consistent with medically accepted clinical practice and are consistent with
the other evidence in the case record; for example, an abnormal exercise stress test or abnormal sleep studies,
appropriately evaluated and consistent with the other evidence in the case record.
Mental findings that establish the existence of a medically determinable impairment
Some individuals with CFS report ongoing problems with short-term memory, information processing, visual-spatial
difficulties, comprehension, concentration, speech, word-finding, calculation, and other symptoms suggesting
persistent neurocognitive impairment. When ongoing deficits in these areas have been documented by mental status
examination or psychological testing, such findings constitute medical signs or (in the case of psychological testing)
laboratory findings that establish the presence of a medically determinable impairment.
Individuals with CFS may also exhibit medical signs, such as anxiety or depression, indicative of the existence of a
mental disorder. When such medical signs are present and appropriately documented, the existence of a medically
determinable impairment is established.
General. Claims involving CFS are adjudicated using the sequential evaluation process, just as for any other impairment. Once a medically determinable impairment has been found to exist (see discussion above), the severity of the impairment(s) must be established. The severity of an individual's impairment(s) is determined based on the totality of medical signs, symptoms, and laboratory findings, and the effects of the impairment(s),
including any related symptoms, on the individual's ability to function.
Also, several other disorders (including, but not limited to, FMS, multiple chemical sensitivity, and Gulf War Syndrome, as well as various forms of depression, and some neurological and psychological disorders) may share characteristics similar to those of CFS. When there is evidence of the potential presence of another disorder that may adequately explain the individual's symptoms, it may be necessary to pursue additional
medical or other development.
Step 2. When an adjudicator finds that an individual with CFS has a medically determinable impairment, he or she must consider that the individual has an impairment that could reasonably be expected to produce the individual s symptoms associated with CFS, as required in 20 CFR 404.1529(b) and 416.929(b), and proceed to
evaluate the intensity and persistence of the symptoms. Thus, if an adjudicator concludes that an individual has a medically determinable impairment, and the individual alleges fatigue, pain, symptoms of neurocognitive problems, or other symptoms consistent with CFS, these symptoms must be considered in deciding whether the individual's impairment is "severe" at step 2 of the sequential evaluation process and at any later steps reached in the sequential evaluation process. If fatigue, pain, neurocognitive symptoms, or other symptoms are found to cause a limitation or restriction having more than a minimal effect on an individual's ability to perform basic work activities, the adjudicator must find that the individual has a "severe" impairment. See SSR 96-3p,
"Titles II and XVI: Considering Allegations of Pain and Other Symptoms in Determining Whether a Medically Determinable Impairment is Severe."
Step 3. When an individual is found to have a severe impairment, the adjudicator must proceed with the sequential evaluation process and must next consider whether the individual's impairment is of the severity contemplated by the Listing of Impairments contained in appendix 1, subpart P of 20 CFR part 404. Inasmuch as CFS is not a listed impairment, an individual with CFS alone cannot be found to have an impairment that
meets the requirements of a listed impairment; however, the specific findings in each case should be compared to any pertinent listing to determine whether medical equivalence may exist.
Further, in cases in which individuals with CFS have psychological manifestations related to CFS, consideration should always be given to whether the individual's impairment meets or equals the severity of any impairment in the mental disorders listings in 20 CFR, part 404, subpart P, appendix 1, sections 12.00 ff. or 112.00 ff.
Steps 4 and 5. For those impairments that do not meet or equal the severity of a listing, an assessment of residual functional capacity (RFC) must be made, and adjudication must proceed to the fourth and, if necessary, the fifth step of the sequential evaluation process. In assessing RFC, all of the individual's symptoms must be considered in deciding how such symptoms may affect functional capacities. See SSR
96-7p, "Titles II and XVI: Evaluation of Symptoms in Disability Claims: Assessing the Credibility of an Individual's Statements" and SSR 96-8p, "Titles II and XVI: Assessing Residual Functional Capacity in Initial Claims."
If it is determined that the individual's impairment(s) precludes the performance of past relevant work (or if there was no past relevant work), a finding must be made about the individual's ability to perform other work. The usual vocational considerations (see 20 CFR 404.1560-404.1569a and 416.960-416.969a) must be applied in determining the individual's ability to perform other work.
Many individuals with CFS are "younger individuals," ages 18 through 49 (see 20 CFR 404.1563 and 416.963). Age, education, and work experience are not usually considered to limit significantly the ability of individuals under age 50 to make an adjustment to other work, including unskilled sedentary work. However, a finding of disabled is not precluded for those individuals under age 50 who do not meet all of the criteria of a specific rule and who do not have the ability to perform a full range of sedentary work. The conclusion about whether such individuals are disabled will depend primarily on the nature and extent of their functional limitations or restrictions. Thus, if it is found that an individual is able to do less than the full range of sedentary work, refer to
SSR 96-9p, "Titles II and XVI: Determining Capability to Do Other Work -- Implications of a Residual Functional Capacity for Less Than a Full Range of Sedentary Work." As explained in that Ruling, whether the individual will be able to make an adjustment to other work requires adjudicative judgment regarding factors such as the type and extent of the individual's limitations or restrictions and the extent of the erosion of the occupational base for sedentary work.
Duration. The medical signs and symptoms of CFS fluctuate in frequency and severity and often continue over a period of many months or years. Thus, appropriate documentation should include a longitudinal clinical record of at least 12 months prior to the date of application, unless the alleged onset of CFS occurred less than 12 months in the past, or unless a fully favorable determination or decision can be made without additional
documentation. The record should contain detailed medical observations, treatment, the individual's response to treatment, and a detailed description of how the impairment limits the individual's ability to function over time.
When the alleged onset of disability secondary to CFS occurred less than 12 months before adjudication, the adjudicator must evaluate the medical evidence and project the degree of impairment severity that is likely to exist at the end of 12 months. Information about treatment and response to treatment as well as any medical source opinions about the individual's prognosis at the end of 12 months are helpful in deciding whether the
medically determinable impairment(s) is expected to be of disabling severity for at least 12 consecutive months.
Continuing Disability Reviews. In those cases in which an individual is found to have a disability based on CFS but medical improvement is anticipated, an appropriate continuing disability review should be scheduled based on the probability of cessation under the Medical Improvement Review Standard. This standard takes into account relevant individual case facts such as the combined severity of other chronic or static impairments and the individual's vocational factors.
General. As with all claims for disability under both title II and title XVI, documentation of medical signs or laboratory findings in cases involving CFS is critical to establishing the presence of a medically determinable impairment. In cases in which CFS is alleged, longitudinal clinical records reflecting ongoing medical evaluation and treatment from the individual's medical sources, especially treating sources, are extremely helpful in documenting the presence of any medical signs or laboratory findings, as well as the individual's functional status over time. Every reasonable effort should be made to secure all available, relevant evidence in cases involving CFS to ensure appropriate and thorough evaluation.
Generally, evidence for the 12-month period preceding the month of application should be requested unless there is reason to believe that development of an earlier period is necessary, or unless the alleged onset of disability is less than 12 months before the date of the application.
Recontacting Medical Sources/Consultative Examinations. If the adjudicator finds that the evidence is inadequate to determine whether the individual is disabled, he or she must first recontact the individual's treating or other medical source(s) to determine whether the additional information needed is readily available, in accordance with 20 CFR 404.1512 and 416.912. Only after the adjudicator determines that the information needed is not readily available from the individual's health care provider(s), or that the necessary information or clarification cannot be sought from the individual's health care provider(s), should the adjudicator proceed to arrange for a consultative examination(s) in accordance with 20 CFR 404.1519a and 416.919a. The type of consultative examination(s) purchased will depend on the nature of the individual's symptoms and the extent of the evidence already in the case record.
Resolution of Conflicts. It should be noted that conflicting evidence in the medical record is not unusual in cases of CFS due to the complicated diagnostic process involved in these cases. Clarification of any such conflicts in the medical evidence should be sought first from the individual's treating or other medical sources. Medical opinions from treating sources about the nature and severity of an individual's impairment(s) are entitled to deference and may be entitled to controlling weight. If we find that a treating source's medical opinion on the issue(s) of the nature and severity of an individual's impairment(s) is well-supported by medically acceptable clinical and laboratory diagnostic techniques and is not inconsistent with the other substantial evidence in the case record, the adjudicator will give it controlling weight. (See SSR 96-2p, "Titles II and XVI: Giving Controlling Weight to Treating Source Medical Opinions," and SSR 96-5p, "Titles II and XVI: Medical Source Opinions on Issues Reserved to the Commissioner.")
Assessing Credibility. In accordance with SSR 96-7p, if the existence of a medically determinable impairment that could reasonably be expected to produce the symptoms has been established, as outlined above, but an individual's statements about the intensity, persistence, or functionally limiting effects of symptoms are not substantiated by objective medical evidence, the adjudicator must consider all of the evidence in the case
record, including any statements by the individual and other persons concerning the individual's symptoms. The adjudicator must then make a finding on the credibility of the individual's statements about symptoms and their functional effects. When additional information is needed to assess the credibility of the individual's statements about symptoms and their effects, the adjudicator must make every reasonable effort to obtain available information that could shed light on the credibility of the individual's statements.
Treating and other medical sources. In evaluating credibility, the adjudicator should ask the treating or other medical source(s) to provide information about the extent and duration of an individual's impairment(s), including observations and opinions about how well the individual is able to function, the effects of any treatment, including
side effects, and how long the impairment(s) is expected to limit the individual's ability to function. Opinions from an individual's medical sources, especially treating sources, concerning the effects of CFS on the individual's ability to function in a sustained manner in performing work activities or in performing activities of daily living are
important in enabling adjudicators to draw conclusions about the severity of the impairment(s) and the individual's RFC. In this regard, any information a medical source is able to provide contrasting the individual's impairment(s) and functional capacities since the alleged onset of CFS with the individual's status prior to the onset of CFS will be helpful in evaluating the individual's impairment(s) and its functional consequences.
Third-party information, including evidence from medical sources who are not acceptable medical sources for the purpose of establishing the existence of a medically determinable impairment, but who have provided services to the individual, may be very useful in deciding the individual's credibility. Information other than an individual's allegations and reports from the individual's treating sources helps to assess an individual's ability to function on a day-to-day basis and to depict the individual's capacities over a period of time. Such evidence includes, but is not limited to:
Information from neighbors, friends, relatives, or clergy;
Statements from such individuals as past employers, rehabilitation counselors, or school teachers about the individual's impairment(s) and the effects of the impairment(s) on the individual's functioning in the work place, rehabilitation facility, or educational institution;
Statements from other practitioners with knowledge of the individual, e.g., nurse-practitioners, physicians' assistants, naturopaths, therapists, social workers, and chiropractors;
Statements from other sources with knowledge of the individual's ability to function in daily activities; and
The individual's own record (such as a diary, journal, or notes) of his or her own impairment(s) and its impact on function over time.
The adjudicator should carefully consider this information when making findings about the credibility of the individual's allegations regarding functional limitations or restrictions.
This Ruling is effective on the date of its publication in the Federal Register.
SSR 96-2p, "Titles II and XVI: Giving Controlling Weight to Treating Source Medical Opinions," SSR 96-3p, "Titles II and
XVI: Considering Allegations of Pain and Other Symptoms in Determining Whether a Medically Determinable
Impairment is Severe," SSR 96-4p, "Titles II and XVI: Symptoms, Medically Determinable Physical and Mental
Impairments, and Exertional and Nonexertional Limitations," SSR 96-5p, "Titles II and XVI: Medical Source Opinions on
Issues Reserved to the Commissioner," SSR 96-7p, "Titles II and XVI: Evaluation of Symptoms in Disability Claims:
Assessing the Credibility of an Individual's Statements," SSR 96-8p, "Titles II and XVI: Assessing Residual Functional
Capacity in Initial Claims," and SSR 96-9p, "Titles II and XVI: Determining Capability to Do Other Work -- Implications
of a Residual Functional Capacity for Less Than a Full Range of Sedentary Work."
 Except for statutory blindness.
 For individuals under age 18 claiming benefits under title XVI, disability will be established if the individual is suffering
from a medically determinable physical or mental impairment (or combination of impairments) that results in "marked
and severe functional limitations." See section 1614(a)(3)(C) of the Act and 20 CFR 416.906. However, for clarity, the
following discussions refer only to claims of individuals claiming disability benefits under title II and individuals age 18
or older claiming disability benefits under title XVI. The concepts in this ruling, however, are also intended to apply in
determining disability based on CFS for individuals under age 18 under title XVI.
 There is considerable overlap of symptoms between CFS and Fibromyalgia Syndrome (FMS), but individuals with
CFS who have tender points have a medically determinable impairment. Individuals with impairments that fulfill the
American College of Rheumatology criteria for FMS (which includes a minimum number of tender points) may also
fulfill the criteria for CFS. However, individuals with CFS who do not have the specified number of tender points to
establish FMS, will still be found to have a medically determinable impairment.
 It should be noted that standard laboratory test results in the normal range are characteristic for many individuals
with CFS, and should not be relied upon to the exclusion of all other clinical evidence in decisions regarding the
presence and severity of a medically determinable impairment.
 In evaluating title XVI claims for disability benefits for individuals under age 18, consideration must also be given to
the possibility of functional equivalence. See 20 CFR 416.926a.
 These steps of the sequential evaluation process are not applicable to claims for benefits under title XVI for
individuals under age 18. See 20 CFR 416.924.
 However, "younger individuals" ages 45-49 who are illiterate in English or unable to communicate in English, whose
past work was unskilled (or who had no past relevant work), or who have no transferable skills, and who are limited to
a full range of sedentary work, must be found disabled under rule 201.17 in Table No. 1 of appendix 2 of the
Medical-Vocational Guidelines in 20 CFR part 404.
 To meet the statutory requirement for "disability," an individual must have been unable to engage in any SGA by
reason of any medically determinable physical or mental impairment which is expected to result in death or which has
lasted or can be expected to last for a continuous period of not less than 12 months. Thus, the existence of an
impairment for 12 continuous months is not controlling; rather, it is the existence of a disabling impairment which has
lasted or can be expected to last for at least 12 months that meets the duration requirement of the Act.
 We may not seek additional evidence or clarification from a medical source when we know from past experience
that the source either cannot or will not provide the necessary findings.
 A medical source opinion that an individual is "disabled" or "unable to work," has an impairment(s) that meets or is
equivalent in severity to the requirements of a listing, has a particular residual functional capacity (RFC), that concerns
whether an individual's RFC prevents him or her from doing past relevant work, or that concerns the application of
vocational factors, is an opinion on an issue reserved to the Commissioner. Every such opinion must still be
considered in adjudicating a disability claim; however, the adjudicator will not give any special sig