Patients Referred to the Chronic Pain Unit for Palliative Treatment With Ozone Therapy Between 2026 and 2029.

The main objective of this study is to analyze the impact on the health-related quality of life of patients with refractory symptoms who have been referred to the Dr. Negrín University Hospital Chronic Pain Unit for adjuvant palliative treatment with ozone therapy between January 2026 and December 2029. Additionally, the study aims to evaluate several specific symptoms, hyperspectral and thermal images, non-invasive clinical parameters related to the Autonomic Nervous System (such as heart rate variability, electrochemical skin conductance, and vibration perception thresholds), oxidative stress and inflammatory parameters, and gut microbiota composition.

Inclusion Criteria: * 1\. Adults ≥ 18 years old. * 2\. Patients referred to the Chronic Pain Unit of the Dr. Negrín University Hospital for symptomatic/palliative treatment with ozone therapy because conventional treatment does not exist, has failed, has offered insufficient results, or is associated with high risk/morbidity. * 3\. After evaluation of symptoms and patients, it exists a potential benefit of adding ozone treatment to the current treatment. * 4\. Patients have no contraindications for ozone treatment. * 5\. Patients must sign the specific Informed Consent for this study and for the ozone treatment. Exclusion Criteria: * 1\. Age \< 18 years old. * 2\. Psychiatric illness or social situations that would limit compliance with study requirements. Contraindication or disability to attend scheduled treatments. * 3\. Contraindication or disability to attend scheduled treatments. * 4\. Uncontrolled clinical conditions (e.g., severe heart failure, massive hemorrhage, status epilepticus). * 5\. Life expectancy \< 6 months. * 6\. Known allergy to ozone. * 7\. Hemochromatosis (for systemic ozone treatment). * 8\. Pregnancy (for systemic ozone treatment). * 9\. Significant Glucose-6-Phosphate Dehydrogenase deficiency (Favism) (for systemic ozone treatment). * 10\. Patients who do not meet the inclusion criteria.