Urine smells like fish – What could be the reason?

Normal urine is nearly odorless and clear. Passing urine which smells like fish may occur due to the causes discussed below.

Causes of ‘urine smells like fish’

Some of the common causes and associated symptoms and treatments of urine which smells like fish are listed below.

1. Urological Causes

• UTI/Urinary Tract Infection: The urinary system is mainly made up of the bladder, kidneys, ureters, and the urethra. Infection of any of these urinary system parts can result in a UTI. The infection causing pathogens can enter the body via the urethra when urinating, or via the bloodstream. Bladder and urethra infection are the most common forms of UTI; the former is also known as cystitis. Women are more prone to UTIs than men due to their genital anatomy, wherein the vagina is very closely located to the anus and the urethra.
  • Patients may suffer from a variety of symptoms including passing urine that smells like fish, cloudy urine, frequent urination, and burning sensations when passing urine. UTI of the kidneys can cause night sweats, fever, and chills.
  • As UTI is mainly caused due to bacterial overgrowth, it is treated with antibiotics. The antibiotics course may last from 2 to 10 days.
  • Prostatitis: Urine which smells like fish may also occur due to prostatitis, wherein the prostate gland experiences inflammation. The prostate is a walnut-shaped organ located just below the bladder in males. It helps maintain sperm quality. Prostatitis may occur due to bacterial infections, but most causes cannot be found.
    • Patients may suffer from pain during urination, passage of urine that smells like fish, and discomfort in the pelvic area. Acute bacterial prostatitis can be serious and cause symptoms such as mild to severe fever, nausea, frequent urination, chills, and urinary urgency.
    • Prostatitis caused due to bacterial infection is treated with oral antibiotics for about a month. Doctors may administer the antibiotics intravenously in severe cases.
    • Vaginitis: It is a condition marked by infection of the vagina by yeast, fungus, or bacteria. Even though these pathogens naturally occur in the vagina, the infection often occurs due their overgrowth and proliferation.
      • Affected women may suffer from swelling of the vagina, pain during urination, vaginal discharge, discomfort during sexual intercourse, vaginal itchiness, and elimination of foul-smelling, putrid urine. The urine may sometimes have a fishy odor.
      • Treatment is dependent on the underlying infection. Vaginitis caused due to bacterial infections is treated with topical and oral antibiotics. Yeast infections are treated with topical antifungal medications. Oral antifungals are usually prescribed for severe yeast infections. Affected women need to avoid sugar-abundant foods till the infection has completely resolved as sugar aids the growth of fungus.
      • Kidney stones: Stinky urine which smells like fish may also occur due to kidney stones. Problems in the composition of urine, such as increase in the levels of oxalate and calcium in urine beyond the threshold, can trigger the formation of crystallized deposits in the kidneys. Such crystals get separated from urine and remain in the kidneys. Over time, they become kidney stones.
        • Affected patients may suffer from extreme and shifting pain in the groin and lower back region, passing of fishy smelling urine, and considerable change in the color of urine. The pain is typically felt when the crystals get stuck in the ureters after moving out of the kidneys.
        • The first treatment option for kidney stones is the intake of lots of water on a daily basis. This can sometimes help remove the stones via urine. Pain is alleviated with painkillers. Severe cases may require surgery.

2. Other causes

• Dehydration: Reduced intake of water can lower the urine volume and make it very concentrated. Such urine exhibits considerable change in both its color and smell. Concentrated urine typically smells like fish or ammonia. Rehydrate the body by drinking lots of water to resolve the issue of concentrated and smelly urine.
• Medicines: Urine odor may also change and smell like fish or yeast due to intake of antibiotics like ciprofloxacin or amoxicillin. The urine may become smelly even when low doses of antibiotics are taken for a short period of time. Intake of multivitamin supplements may also cause urine to smell like fish.
• Pregnancy: A lot of women tend to suffer from UTIs during pregnancy. As discussed above, UTIs may cause urine that smells like fish. Urine may also become smelly during pregnancy due to other uncommon causes.
• Beverages: Intake of excessive amounts of coffee or caffeinated beverages can result in elimination of foul, fishy-smelling urine. Caffeine has diuretic qualities which increases urination, causes dehydration, and eventually results in smelly urine.
• Liver abnormalities: Elimination of urine that smells like fish can also be a symptom of an underling liver problem. Liver diseases can hamper the organ’s functioning and cause darkened and smelly urine. In people with properly functioning liver, only traces of bilirubin is released into the urine. Liver malfunction causes large quantities of bilirubin to get passed into the urine, causing it to attain a unique dark amber color and become really smelly. Treatment of pre-existing liver disease can help resolve the problem.
• Diabetes: Diabetes is a condition marked by high levels of blood sugar. The glucose often passes into urine, resulting in sweet, fishy-smelling urine. This is especially true in cases of untreated or mismanaged diabetes wherein the diet restrictions are not adhered to by the patient.
• Phenylketonuria: It is a metabolic disorder characterized by inability of the body to breakdown the phenylalanine amino acid. This results in increased concentration of the protein in urine and blood, leading to elimination of strong and putrid urine that smells mousy, fishy, or musty.
• Certain foods: Intake of some kinds of food items, such as asparagus can also result in urine that smells like fish. It may be noted that the process of asparagus breakdown by the body results in release of sulfur as a byproduct. This sulfur is what gives the urine its distinctive rancid, fishy smell.
• Trimethylaminuria: It is a genetic disorder marked by smelly body odor and elimination of urine that smells like fish. People without the genetic defect may suffer from trimethylaminuria due to hormonal imbalances, kidney or liver problems, or intake of certain diets. Treatment includes lifestyle and diet changes as well as intake of medications.