Out of the global population of 7 billion, the elderly population is about 800 million, and the world has entered an aging society. China has the largest elderly population in the world, accounting for one-fifth of the global elderly population. Statistics from the World Health Organization show that one-third of the elderly, or 267 million worldwide, do not die of natural causes, but are directly related to improper clinical use of medications. medications for people over 60 years of age account for 50% of all medication consumption. Case presentation The patient, female, 78 years old, was admitted to the hospital in March 2010 due to an acute attack of coronary heart disease. She also had hyperlipidemia, hypertension, type 2 diabetes mellitus, osteoporosis and insomnia. After admission, coronary angiography stenting was performed. After consultation, cardiology, endocrinology, neurology and orthopedic surgeons prescribed appropriate medications for their respective diseases, totaling 15 drugs. 2 days later, liver function tests showed that serum transaminases were 10 times higher than the normal values at the time of admission, while fasting blood glucose was not controlled but increased to 9.0 mmol/L. A comprehensive analysis of the patient’s medication revealed that it was due to adverse drug reactions, and the use of drugs All seven drugs had the side effect of increasing liver enzyme levels, resulting in superimposed drug hepatotoxicity, while statins affected the metabolic and endocrine systems, causing blood glucose to rise. After the number of drugs was reduced to the mandatory four, the patient’s condition was controlled. The most prominent clinical feature of medication use in the elderly is polypharmacy. It is generally believed that when more than five types of drugs are taken, the risk of medication use may be greatly increased, including drug-induced adverse reactions, drug interactions and increased drug costs, and patients’ medication adherence and quality of life are reduced. Polypharmacy is prevalent among older patients worldwide. According to statistics, 57% of older adults over the age of 65 in the United States take an average of 5 or more medications per day, and 12% take 10 or more medications. Our elderly population takes an average of 6 medications per day. A study in the Journal of the American Medical Association (JAMA) pointed out that the incidence of adverse reactions was about 4.2% when 5 drugs were combined and up to 45% when 20 or more drugs were combined. High sensitivity, low tolerability and poor safety: The incidence of adverse reactions due to the same drugs is much higher in the elderly than in younger people. This is related to the pharmacokinetic characteristics of the elderly. Compared with young people, the function of all organs in the elderly is reduced, especially the function of important organs such as heart, liver and kidney. Take the kidney as an example, the renal blood flow in the elderly is only 40% to 50% of the adult, so the rate of excretion of drugs from the kidney is slowed down, and the increase in blood concentration and drug half-life make the elderly more prone to adverse drug reactions, attention should be paid to adjusting the dosage of aminoglycosides, digoxin, antihypertensive drugs and anticoagulants (such as warfarin). According to the physiological condition of the elderly, the dose of medication for the elderly aged 60 to 80 years is generally 75% to 80% of that for adults, and the dose for the elderly aged 80 years or above is 50% of that for adults. The “3S” principle of individualized medication for the elderly is the principle of simplification, that is, the elderly should use fewer and more precise medications, minimize the number of medication types, and it is best to combine no more than 5 kinds of drugs. ion antagonists can treat hypertension and angina pectoris. The principle of support and care means to treat the primary disease actively and to promote the patient’s own regulation function through spiritual, dietary or exercise therapy for the secondary disease. At the same time, we encourage friends and relatives to care for the mental state of the elderly, which can greatly improve the overall effectiveness of the treatment of elderly diseases. The principle of follow-up (Survey) is to insist on regular review, observe the efficacy and adverse reactions, and adjust the medication plan in time, which is the final guarantee of truly individualized medication.