Symptoms of decline in sexual function after a man’s fortieth year mainly include loss of libido, obstruction of normal erection, short duration of sexual life, and other accompanying symptoms. 1. Decreased libido: For men with decreased sexual function, there will be decreased libido, typical symptoms are lack of sexual fantasies, sexual impulses, decreased pleasure and excitement in sexual life, and so on. 2. Obstruction of normal erection: men will have less serious erectile dysfunction, such as not being able to have an erection automatically when they are excited, or the speed of erection is slowed down, and the erection is not hard enough, or becomes soft after insertion, and so on. 3. Short sexual life: mainly the speed of ejaculation increases, the sexual life is short, and in serious cases, ejaculation may occur within 3 minutes, and there are symptoms such as weak ejaculation. 4. Other accompanying symptoms: patients may be accompanied by spermatorrhea, physical weakness, dizziness, ejaculation, and weakness after sex. Once the above symptoms appear, patients should consult the doctor in time and have a systematic examination.