Potassium infusion generally refers to the intravenous infusion of potassium ions. Potassium infusion is not painful in some people because of the speed of the infusion and the concentration of the potassium, as well as the factor of individual differences. 1. Infusion speed: The speed of potassium infusion needs to be within the normal range as prescribed by the doctor, so that it is generally not painful. On the contrary, potassium ions can cause irritation to blood vessels. If the infusion speed is too fast, potassium ions may irritate the nerve fibers on the patient’s blood vessel wall, resulting in local pain and, in severe cases, may also cause venous inflammation. 2. Concentration of potassium ions: The concentration of potassium needs to be within the normal range, so that it will not cause pain. Potassium chloride commonly used in clinical practice belongs to a kind of hypertonic cationic solution, which has a relatively high osmotic pressure and strong irritation. When potassium chloride solution is fed locally, too high a concentration of potassium ions will cause the local blood to have a significantly higher concentration of potassium ions within a short period of time. Too high a concentration of potassium ions will stimulate the nerve cells, which will also lead to nociceptive reactions in the patient. 3. In addition, there are individual differences in pain perception. Some patients have a higher pain threshold and do not easily feel pain during potassium infusion. The use of drugs must follow the doctor’s instructions, pay attention to the speed of infusion, and do not blindly use drugs on your own, so as not to cause adverse consequences.