What are the most common causes of dysuria (pain on passing urine)?

The most common cause of dysuria is a urinary tract infection, especially in young females. This is often associated with increased frequency and urgency of passing urine.

This is sometimes accompanied with fever, cloudy smelly urine or visible blood in the urine. This is usually easily treated with a short course of antibiotics.

Vaginal infections such as from yeast can also cause dysuria.

Sexually transmitted infections such as gonorrhea, chlamydia or herpes also cause dysuria, and can be accompanied by genital itching and abnormal discharge from the urethra (men) or vagina.

Other less common causes of dysuria could be a bladder stone or bladder cancer. If the dysuria is persistent, and does not respond to antibiotics, one of these causes needs to be considered.

The most common cause of dysuria in a young lady would be urinary tract
infection. Infection can result in inflammation of the urethra (urine tube)
and the bladder, referred to as urethritis and cystitis respectively.

Urinary tract stones e.g bladder stones can also cause dysuria and in the
rare occasion, bladder malignancies (which is highly unlikely in your age
group).