[Tiredness/Fatigue-S3 guideline update].

Background: Fatigue is one of the most common reasons for seeking medical counseling in the family medicine (FM), often entailing diagnostic uncertainty. Patients use terms describing emotional, cognitive, physical, and behavioral aspects. A number of biological, mental, and social causes may underlie the symptom of fatigue, often in combination. This guideline describes the procedures to be applied for primary undetermined symptomatology.

Methods: The experts involved conducted a systematic search using the terms for fatigue in the context of FM in PubMed, Cochrane Library and via manual search. Concerning related guidelines, the National Institute for Health and Care Excellence (NICE) guideline was used for myalgic encephalitis/chronic fatigue syndrome (ME/CFS). In a structured consensus process, broad approval of the core recommendations/background text of the revised guideline was attained.

Most important messages: 1) Alongside gathering information concerning the symptom characteristics, the anamnesis aims to collect information about pre-existing health conditions, sleeping behavior, use of drugs and psychosocial factors. 2) Depression and anxiety as two common causes will be identified based on screening questions. The occurrence of post-exertional malaise (PEM) will be inquired. 3) The following basic diagnostics are recommended: physical examination, laboratory tests (blood glucose, full blood count, blood sedimentation/CRP, transaminases/γ-GT, TSH). 4) Further examinations should be conducted only in case of specific indications. 5) A biopsychosocial approach is to be adopted. 6) Behavioral therapy and symptom-oriented activating measures can improve fatigue in underlying diseases and undetermined fatigue. 7) In case of PEM, further ME/CFS criteria should be collected and patients have to be supervised accordingly.