Causes of a Strong Urine Smell

If you notice a strong smell to your urine, your first thought may be that something is wrong. If you are a typically healthy adult, however, the cause may be as simple the foods you're eating or not drinking enough fluids. Treatable conditions such as urinary tract infections or diabetes may alter the smell of urine in adults as well. If you have signs of an infection or other illness, contact your healthcare provider for advice.

Food Odors

Some of the chemicals that give foods their distinctive aroma are passed in the urine. A number of foods can cause your urine to have a strong odor, especially if you aren't drinking much water. Common culprits include garlic, onions, asparagus, and coffee. Large amounts of fish, meat and eggs in your diet might also cause a change in urine odor. Certain medications and supplements, such as B vitamins, might also cause an usual urine odor.

Stagnant Urine

Fresh urine has little to no odor. But if urine sits for a time -- as can happen when a person is wearing protective underwear or an incontinence pad -- the urine will begin to smell like ammonia. The smell is caused by bacteria that break down urea, a substance that is excreted in urine. Changing the disposable undergarment or absorbent pad and washing the area with soap and water will remove the odor.

Concentrated Urine

If your urine is dark and strong smelling, you may be not be drinking enough fluids. This is known as hypohydration. On average, men need approximately 4 quarts of total fluid daily and women need roughly 3 quarts, according to the Institute of Medicine. Taking in less fluid than your body needs or losing too much fluid through sweating, vomiting or diarrhea can result in hypohydration, or even dehydration. In otherwise healthy adults, simply increasing your intake of water can return your urine to its normal color and odor.

Urinary Tract Infection

If you notice an ammonia smell immediately after you urinate, you might have a urinary tract infection (UTI). A very strong ammonia smell may indicate a severe infection, although some people with a UTI do not notice a change in urine odor. Other symptoms of a UTI include burning pain with urination and the need to urinate frequently but passing little urine. Fever and back pain might also occur. Contact your healthcare provider if you suspect you might have a UTI.

Urine Ketones

A sweet or fruity urine odor is typically caused by chemicals called ketones, byproducts of fat breakdown. Ketones in the urine can be a sign of undiagnosed or poorly controlled diabetes. You can also have high concentrations of ketones if you're not eating much due to dieting or the stomach flu. If you're not dieting and notice a fruity odor to your urine, contact your doctor right away -- especially if you have diabetes.

Abnormal Drainage

An abnormal connection between organs, called a fistula, can occur between the vagina or bowel and the urinary tract. Because the urine is not draining properly, it typically takes on a strong, unpleasant odor. A fistula between the urinary tract and bowel can also cause passage of gas and stool-like material in the urine. Contact your doctor immediately if you have symptoms that might indicate a fistula.

Reviewed by: Tina M. St. John, M.D.