The Medication Review in the Pharmacotherapeutic Follow-up Service (PFS) seems to be an effective method to study long-term drug safety in the outpatient setting. The adverse drug reactions (ADRs) that are not immediately obvious are difficult to identify and sometimes can be confused with a more common condition. Misdiagnosis by not associating the symptoms of AMR to its pharmacological cause causes its masking and hinders its detection. Detect in the SFT service the diagnostic errors related to the non-detection of adverse reactions to statins. The data obtained from the medication review at the Pharmacotherapeutic Follow-up Service (PFS) were pooled for analysis. The patients who received the service were selected with the "DLGM screening" tool, an acronym "Diagnosis load Generated by Medications", that allows us to describe adverse drug reactions (ADRs), when their symptoms are attributed to a pathology, without considering medication as a possible underlying cause.Only the results of patients over 60 years of age, who after a prolonged period of statin use gradually presented musculoskeletal disorders (MSD) and other symptoms theoretically described as possible ADRs, are shown. In 66 % of the cases, corresponding to 14 patients out of a total of 21 studied, the physician modified the treatment and in 92% of these cases there was improvement and a decrease of the consumption of analgesics drug, anti-inflammatory and other drugs used to treat ADR symptoms. DLGM screening identified hidden AMRs in 62 % of patients.