Urinary Tract Infection (UTI): This is often the most common cause of urinary frequency, especially in women. Bacterial infection of the bladder or urethra leads to irritation of the bladder wall, causing a sensation of needing to urinate more frequently.

Benign Prostatic Hyperplasia (BPH): In men, an enlarged prostate can press against the urethra, affecting urine flow and leading to symptoms of urinary frequency, urgency, and nocturia.
Overactive Bladder: A condition characterized by a sudden, intense urge to urinate, sometimes accompanied by unintentional urination. It can be caused by a variety of factors including neurological disorders, bladder problems, or certain medications.
Diabetes Mellitus: High blood sugar levels can lead to increased urine production (polyuria) and, consequently, urinary frequency. This is due to the body's attempt to rid itself of excess glucose through urine.
Diuretic Use: Medications that increase urine production, such as diuretics used to treat hypertension or heart failure, can cause urinary frequency as a side effect.

Bladder Cancer: Although less common, bladder cancer can cause urinary frequency, especially if the tumor is located in a position that irritates the bladder wall or obstructs urine flow.
Kidney Stones: Small stones in the urinary tract can cause severe pain and irritate the bladder, leading to frequency and urgency.
Neurogenic Bladder: Conditions affecting the nervous system, such as multiple sclerosis, spinal cord injuries, or stroke, can disrupt normal bladder control, leading to urinary frequency among other symptoms.
Interstitial Cystitis: A chronic condition causing bladder pressure, bladder pain, and sometimes pelvic pain. The symptoms can worsen as the bladder fills and may improve with urination.

Tuberculosis of the Urinary Tract: A rare infection that can affect the kidneys or bladder, causing a variety of symptoms including urinary frequency.
Sarcoidosis: A condition in which inflammatory cells (granulomas) form in various organs, including the kidneys, which can lead to urinary frequency among other symptoms.
Eosinophilic Cystitis: A rare condition characterized by an eosinophilic infiltration of the bladder wall, which can cause urinary frequency, pain, and hematuria.
Bladder Endometriosis: A form of endometriosis where endometrial tissue grows in the bladder, potentially causing cyclical urinary symptoms including frequency during menstruation.