Informed consent is part of a process of communication useful to obtain an agreement (conscious, voluntary and free) between doctors and patients. Mesotherapy is based on the introduction of drugs by intradermal route in order to obtain a dose-sparing effect with respect to deeper administration. Opioids are the most appropriate therapy for patients who do not respond to other therapies. Proper communication between doctor and patient, including an explanation of the potential benefits, limitations and risks (even mild), is recommended both in clinical practice and research. Active participation of the patient has the advantage of better control of adverse events, both of mesotherapy and opioid-based therapy. This information-education process returns to the fundamental concept of "first do no harm" and set a "therapeutic partnership" with patients.