Various ME/CFS patient groups disputed the benefits of the therapies and stated that GET can make the illness more severe.Comorbid conditions can occur in CFS that may interact with and exacerbate the symptoms of CFS. Appropriate medical intervention for these conditions may be beneficial. The most commonly diagnosed include fibromyalgia, irritable bowel syndrome, depression, anxiety, allergies, and chemical sensitivities. Pacing
Pacing, or activity management, is an illness management strategy based on the observation that symptoms tend to increase following mental or physical exertion, and was recommended for CFS in the 1980s. It is now commonly used as a management strategy in chronic illnesses and in chronic pain.Its two forms are symptom-contingent pacing, in which the decision to stop (and rest or change an activity) is determined by self-awareness of an exacerbation of symptoms, and time-contingent pacing, which is determined by a set schedule of activities that a patient estimates he or she is able to complete without triggering post-exertional malaise (PEM). Thus, the principle behind pacing for CFS is to avoid overexertion and an exacerbation of symptoms. It is not aimed at treating the illness as a whole. Those whose illness appears stable may gradually increase activity and exercise levels, but according to the principle of pacing, must rest or reduce their activity levels if it becomes clear that they have exceeded their limits.
The 2015 definition by the National Academy of Medicine (then referred to as the "Institute of Medicine") is not a definition of exclusion (differential diagnosis is still required). "Diagnosis requires that the patient have the following three symptoms: 1) A substantial reduction or impairment in the ability to engage in pre-illness levels of occupational, educational, social, or personal activities, that persists for more than 6 months and is accompanied by fatigue, which is often profound, is of new or definite onset (not lifelong), is not the result of ongoing excessive exertion, and is not substantially alleviated by rest, and 2) post-exertional malaise* 3) Unrefreshing sleep*; At least one of the two following manifestations is also required: 1) Cognitive impairment* 2) Orthostatic intolerance" and notes that "*Frequency and severity of symptoms should be assessed. The diagnosis of ME/CFS should be questioned if patients do not have these symptoms at least half the time with moderate, substantial, or severe intensity. "Clinical practice guidelines are generally based on case descriptions, with the aim of improving diagnosis, management and treatment. An example is the ME/CFS guideline for the National Health Services in England and Wales, updated in 2021. Other guidance can be found at the New York Department of Health. Differential diagnosis
Certain medical conditions can cause chronic fatigue and must be ruled out before a diagnosis of CFS can be given.