There is no such thing as drug immunity, and the possible reasons why a drug does not work after taking it are: 1. the body is resistant to the drug; 2. the drug cannot treat the disease through its pharmacological mechanism; 3. special drugs are taken together to reduce the efficacy of the treatment. Drug resistance is divided into natural resistance and acquired resistance. Natural resistance is due to the bacterial chromosome genetically determined by its chemical structure and composition is different, itself is not sensitive to antibacterial drugs. Acquired resistance is due to the bacteria after long-term contact with antibacterial drugs by changing their own metabolic pathway or structure, so that they are not killed by the original antibacterial drugs. In addition, certain drugs taken together will reduce the efficacy of treatment, such as nifedipine and the anti-tuberculosis drug rifampicin when taken together, it will make the effective drug concentration of nifedipine lower, thus reducing its antihypertensive treatment effect. Therefore, it is recommended to consult a physician before taking medication on your own and then use the medication reasonably.