Weakness can be caused by a variety of reasons, mainly urinary system diseases, reproductive system diseases and cranial diseases. 1. Urinary system diseases: Urinary system diseases such as cystitis, kidney failure and urinary stones can lead to weakness because the nerves innervating the bladder or urethra are damaged. 2. Reproductive system diseases: Weakness can also be seen in reproductive system diseases. It is mainly seen in men with diseases such as prostatitis and prostate enlargement, because damage to the prostate gland can lead to the overflow of prostate fluid and thus produce a feeling of urination, but there is not much real urine, so you will feel weak in urination and defecation. 3. Craniocerebral disease: If you suffer from craniocerebral injury, cerebral hemorrhage or cerebral embolism and other diseases, it will lead to the symptoms of urinary and fecal weakness because of the damage to the nerves. If you have symptoms of urinary and fecal weakness, it is recommended that you go to the hospital as soon as possible for diagnosis and treatment.