Taking isosorbide nitrate tablets need at least 24 hours interval before using tadalafil, long-term patients taking isosorbide nitrate tablets are not recommended to take tadalafil. Isosorbide nitrate tablets are vasodilator drugs used in the treatment of patients with angina pectoris, coronary heart disease, etc. Tadalafil is a drug used to treat erectile dysfunction in men, which is a phosphodiesterase 5 inhibitor that promotes erection by increasing penile blood flow. Both have a vasodilatory effect on blood vessels, which can lead to hypotension and even life-threatening if combined. If patients need to take isosorbide nitrate tablets for a long time, it is not recommended to take tadalafil, if patients occasionally take isosorbide nitrate tablets, they can take tadalafil after 24h after taking it, when isosorbide nitrate tablets are metabolized completely in the body. Isosorbide nitrate tablets and tadalafil are both prescription drugs and need to be used under the guidance of a doctor.