The efficacy of drugs on the body, in addition to fully exerting the therapeutic effect, may also continue to cause some adverse reactions that are unrelated to the therapeutic goal of the drug due to various reasons, which is what we call side effects of drugs.

The side effects of drugs can generally be divided into four categories: side effects, toxic and side effects, allergic symptoms, and secondary infections (also known as superinfections). Side effects have differences in size and severity, which can cause discomfort, worsen the condition, cause new diseases, and even lead to death. How to maximize the efficacy of drugs and minimize side effects is an important issue that clinical medicine needs to address.

In real life, the incidence of drug side effects is very high, especially when used for a long time or in large doses, the situation is more serious and may even appear severe adverse reactions. Strictly speaking, almost all drugs may cause side effects under certain conditions. However, if drugs are used reasonably, side effects can be prevented or minimized to the least extent. This requires that everyone fully understand the pharmacological characteristics of the drug before taking it, strictly control the scope of application of the drug, adopt appropriate dosages and treatment processes, and establish contraindications. During the medication process, close attention should be paid to changes in the condition and timely treatment of the side effects caused by the drug, with comprehensive solutions to minimize adverse effects. For some drugs, due to insufficient treatment experience, there is a lack of observation and understanding of their side effects, so they should be used with great caution. The characteristics of side effects can be divided into:

Recessive Side Effects (Adverse Reactions): Effects that should occur when the drug is used in normal dosages and are related to the pharmacological specificity of the drug but unrelated to the purpose of taking the drug. They are generally mild and often transient, appearing along with the therapeutic effects. The side effects of drugs with low organ selectivity or general effects may be more common.

Recessive Side Effect and Adverse Effect Function: Due to individual differences, pathological conditions, or the concurrent use of other medications, sensitivity may increase, leading to certain effects or organ damage at therapeutic doses. Generally, it is an increase in therapeutic value. Overdosage may be defined as the occurrence of excessive therapeutic value when using the recommended dosage.

Recessive Post-Withdrawal Effect: Pharmacological effects remaining after the drug concentration in the blood has dropped below the threshold concentration after discontinuation.

Recessive First Dose Effect: Some patients may experience an unacceptable strong reaction when they first take a certain type of medication because the body has not integrated the effects of the drug.

Recessive Secondary Reaction: Adverse effects caused by the therapeutic effects of the drug, also known as therapeutic discrepancy, which is not the effect of the drug itself, but rather an indirect result of its key therapeutic effect.

Recessive Hypersensitivity Reaction (Allergic Symptoms): Abnormal immune reactions caused by the drug or its metabolic substances in the body acting as antigens to stimulate the body. The occurrence of this type of reaction is unrelated or has little to do with the dosage of the drug, and it can occur with both high and low dosages. Clinical manifestations include rash, angioneurotic edema, anaphylactic shock, serum sickness syndrome, asthma, and so on.

Recessive Allergic Reaction (Allergic Reactivity): Due to abnormal genetic inheritance, a very small number of patients may develop adverse reactions unrelated to the therapeutic value of the drug after taking the medication. This reaction is related to genetic inheritance and unrelated to therapeutic value. Most cases are due to a lack of certain enzymes in the body, causing reactions when the drug is metabolized.