1, the same ingredients, combined use caused by overdose. Now many drugs are compounded, if you want to “get better fast” and use two drugs on their own, easy to cause an overdose of certain ingredients. For example, the common cold medicine Tylenol, white plus black, etc. contain antipyretic and analgesic ingredients acetaminophen. If used at the same time, too much of this ingredient can easily cause hematopoietic system and liver and kidney damage. Many people ignore this point because of the different trade names, so it is important to look at the ingredients before using the drug. 2, “inbred” drugs together, each other “suppress” each other. Azithromycin and clarithromycin are both macrolide antibiotics, which play an antibacterial role by inhibiting bacterial protein synthesis. Although the same role, but if used at the same time, the two drugs will appear antagonistic, that is, mutual suppression of each other’s role, but make the efficacy of the decline, the situation of 1 + 1 < 2. 3, the same pharmacological effect, affecting each other to play. If the combination of two drugs belong to different kinds, but the pharmacological mechanism of action is the same, the efficacy will also be reduced. For example, gliclazide is a sulfonylurea hypoglycemic drug, and nateglinide is a non-sulfonylurea hypoglycemic drug, both of which can promote the secretion of insulin by pancreatic β cells and exert hypoglycemic effects. Because they have the same object of action, if used at the same time, the two drugs will "race" and compete with each other to affect each other's performance, resulting in reduced efficacy. 4, the same toxic side effects, combined with aggravated toxicity. Some different kinds of drugs have the same toxic side effects, the combination of drugs, the toxic side effects will be superimposed, therefore should not be used together. For example, amlodipine tablets and felodipine extended-release tablets are both drugs for the treatment of hypertension, and both can cause lower limb edema, palpitations, headache adverse reactions, if used together, these symptoms will be more obvious. 5. Interaction and damage to the kidney. Sulfonamides can produce substances that damage the kidneys in an acidic environment, and should not be used in combination with acidic drugs. And the main ingredient of the Chinese medicine Da Shanzha Wan for indigestion, hawthorn, contains acidic substances such as tannin, vitamin C and fatty acids, which can reduce the solubility of sulfonamide entering the body and easily precipitate crystals in the kidney tubules, causing crystalluria or hematuria. Especially when taking sulfa drugs in large doses and for a long time, you should avoid taking them together with this kind of Chinese medicine. Other Chinese medicines containing organic acids, such as honeysuckle, dandelion and other Chinese medicines, should not be taken at the same time with sulfa drugs.