Whether or not there are any effects of a subcutaneous injection that has been given as an intramuscular injection is related to whether or not the patient is experiencing symptoms of discomfort. If an incorrect injection has been given, it is recommended that the patient be closely observed for at least 30 minutes. Subcutaneous and intramuscular injections are two completely different methods of injection. Subcutaneous injections are commonly used for drug sensitivity tests, insulin injections, preventive inoculations, etc. Intramuscular injections are mostly used for larger dosages or more stimulating drugs. As the blood in muscle tissue is more abundant, the absorption of drugs is more rapid than subcutaneous injection. Therefore, if the subcutaneous injection of drugs for intramuscular injection, should be closely observed changes in the condition. In addition, it should be noted that, if used for skin test, should be prepared to rescue drugs. For some drugs, subcutaneous injection and intramuscular injection will have different effects. For example, epinephrine, subcutaneous injection can be used in cardiopulmonary resuscitation cardiac arrest, anaphylactic shock, severe hypotension and other cases; intramuscular injection can also be used for anaphylactic shock and other cases, but the injection site due to the intense vasoconstriction of the blood vessels, which will produce severe pain. Subcutaneous injection of the same drug has a lower absorption rate than intramuscular injection. The specific use of which injection, should be selected under the guidance of the doctor.