What Causes Cloudy or Strong-Smelling Urine?

Urine is usually clear and pale yellow. If it suddenly appears cloudy or has a strong smell, it may require attention. While this does not always mean something is wrong, it can be an early sign of several possible issues—some harmless and others more serious.

One of the most common causes of cloudy or foul-smelling urine is a urinary tract infection (UTI). When bacteria infect the bladder or urethra, they trigger the release of white blood cells and byproducts that can make the urine appear cloudy and smell unpleasant. This is often accompanied by other symptoms like burning during urination, frequent urges to go, or pelvic discomfort.

Another common reason is dehydration. When you do not drink enough fluids, your urine becomes more concentrated. It may appear darker, more cloudy, and have a strong odor due to the buildup of waste substances like urea and ammonia. Simply increasing water intake can often improve the appearance and smell of urine.

Diet also plays a role. Foods like asparagus, onions, garlic, and coffee can temporarily change the odor of your urine. Vitamin supplements, especially vitamin B6, and certain medications may do the same. These changes are usually harmless and go away on their own.

In some cases, kidney stones or bladder stones may cause cloudy urine if they irritate the lining of the urinary tract or cause bleeding. People with these conditions may also experience pain, difficulty urinating, or blood in the urine.

Cloudy urine can also be linked to proteinuria—the presence of protein in urine—which may be a sign of kidney disease. If this persists, your doctor may order a urine test or further kidney function tests like serum creatinine or eGFR.

Strong-smelling urine on its own is not always a cause for concern, especially if it only happens occasionally. However, if the cloudy appearance or smell continues, or if it comes with pain, fever, or other symptoms, you should speak with a doctor or a urologist.