Inclusion Criteria:  confirmed diagnosis of fibromyalgia (FSQ) Pain VAS >= 4,0 Signed declaration of consent  Exclusion Criteria:  Participation in other clinical studies Contraindications for hyperthermia (severe cardiovascular diseases, tumour diseases, acute infections, pregnant and breastfeeding women) Acute and / or feverish microbial infections Patients with severe somatic, rheumatic concomitant endocrine or neurological diseases, in particular neurological diseases associated with cognitive disorders, severe liver or kidney and cardiac diseases Patients who are permanently treated with opioids, cannabis, immunosuppressive drugs (e.g. corticoids, immunosuppressants) or alpha/beta-A(nta)gonists due to a disease from the group described above Patients with pain due to a serious psychiatric illness (bipolar disorder, psychosis, personality disorder, severe depression, substance abuse) and serious systemic or neurological disorders