It may be normal for TB drugs to not work for four months; TB drugs need to be taken for at least six months and may not work for four months. However, it may also be due to drug resistance, which is not normal. TB drugs are mainly used to treat chronic wasting infections caused by Mycobacterium tuberculosis, and the current drugs are isoniazid, pyrazinamide, rifampicin and ethambutol. Tuberculosis drugs need to be treated for at least six to twelve months, if the patient is taking tuberculosis drugs for four months, did not play a therapeutic effect, mostly due to insufficient drug therapy, is a normal phenomenon. It is recommended that the patient go to a regular hospital to complete the drug sensitivity test to clarify whether it is due to drug resistance. If there is drug resistance, it is an abnormal situation. Can follow the doctor’s instructions to change the drug, or increase the dose of drugs and other ways to improve, but need to be carried out under the guidance of the doctor, do not change or increase the dose of drugs without authorization, so as not to affect the therapeutic effect, damage to the body’s health. There are many reasons why the tuberculosis drug has no effect after taking it for four months, and it is recommended that the patient consult a doctor in time to find out the cause of the disease.