Why Does My Urine Smell Like Fish?

Certain medications and fluid intake may cause the odour of urine to change. But a strong fishy odor may be an indicator of a severe medical issue.

If you notice that your urine has taken up a fishy-smelling odour, you may have to wait for a couple of days to see if it clears up on its own. If the odour is associated with other symptoms such as lower back pain, or difficulty urinating, you should contact your doctor immediately.

READ ALSO: 8 Causes of White Particles in Urine

A fishy odor is rare in urine. Many of the causes are not serious, but it can indicate a severe condition, such as damage to the kidneys or liver.

In some cases, fishy odour may be caused by a chemical called trimethylamine oxide. When a fish dies and bacteria begin to decompose the tissue, this chemical is released and converted to trimethylamine (TMA), which causes the fishy odor. A fishy smell in urine may be caused by the presence of bacteria, TMA, or an interaction between them.

READ ALSO: Five Possible Complications of Holding Your Urine

From a study in 2013 it was discovered that most healthy people produce chemicals that break down TMA, which stops them from smelling like fish, even when they have eaten fish of late or have a lot of bacteria in their systems.

Minor Causes

Minor causes of fishy urine odour may resolve on its own in a few days without treatment.


Certain foods, including asparagus and fish, can make the urine give off offensive odour. If foods are responsible, the smell should go away after a few hours.

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The urine can become concentrated as a result of pregnancy. This can lead to a stronger smell, and it may make a fishy smell more noticeable. See a doctor if the smell persists after two days. Also, dehydration during pregnancy can make the urine look darker or smell worse. A person who is pregnant and noticing these symptoms should ensure they drink lots of water.

Vitamins and supplements

Some vitamins and supplements can make the urine smell fishy, especially supplements of calcium, vitamin B6, and vitamin D. The odor may be more evident when a person is dehydrated. If an individual stops taking these supplements and their urine still smells fishy, they should see a doctor.

READ ALSO: Urinary Tract Infections, UTIs in Men

Medical conditions

Fishy-smelling urine may be the first indication of a mild or severe health problem. Some people may have no other symptoms or several. The following causes often require medical attention:

Urinary tract infections (UTIs)

When too much harmful bacteria grow in the urinary tract, it causes urinary tract infection, UTI. This can make the urine smell. UTI may cause no symptoms. However when symptoms occur, they often include:

Most UTIs can be treated with antibiotics. A UTI may spread to the kidneys if left untreated for long period.

Bacterial vaginosis (BV)

This bacterial infection in the vagina causes discharge with fishy odour. While it does not affect the urine, a person may notice the odor while using the bathroom.

The smell and other symptoms may escalate immediately after sex. Women with BV may believe that they have a yeast infection, but the fishy smell is a distinguishing feature. Some other symptoms include:

  • pain during sexual intercourse
  • burning in or around the vagina
  • frothy vaginal discharge
  • gray discharge from vagina

BV is common in sexually active women. Some sexually transmitted infections may also cause an uncommon odor, and it is vital to see a doctor for testing.

Fish odor syndrome

Trimethylaminuria, better known as fish odor syndrome, is a rare disorder that causes the bodily secretions of a person to smell like fish. The odor can arise from the saliva, sweat, or urine. A person develops this condition when they are not able to break down TMA.

The disorder is passed genetically and causes no other symptoms in most cases. A person emitting a fishy odor that persists, in spite of good hygiene, should see a doctor.

Liver failure

Liver helps the body to filter out toxins. When the liver is not functioning properly, it releases a substance called bilirubin into the blood. This can pass into the urine, giving it an offensive odour.

READ ALSO: Liver Failure: Causes, Treatment and Prevention

Symptoms of liver failure include:

Kidney problems

The kidneys filter the urine, which helps to remove toxins from the body. When the urine smells, it may mean that the kidneys are not functioning correctly, often due to kidney stones or infections.

READ ALSO: Kidney Failure: Symptoms, Stages, Causes, and Treatment

Symptoms of a kidney infection may include:


Prostatitis is swelling and inflammation of the prostate, and it is often the result of an infection. People with prostatitis may notice changes in urination, including a fishy smell.

Symptoms of prostatitis include;

  • lower back pain
  • pain in the anus, perineum, or scrotum
  • weak urine stream
  • chills and body aches

Treatment depends on the cause of the inflammation. A doctor may prescribe medication, such as antibiotics and pain relievers, or they may recommend surgery. The pain can be managed at home with warm sitz baths.

Anyone with one or more of the following conditions should see a doctor immediately if they suspect that their liver is failing:

  • cirrhosis
  • hepatitis
  • fatty liver disease
  • metabolic disorders
  • any autoimmune disease
  • bile duct disease

Treatment will depend on the extent of the liver failure, but it may include medication, hospitalization, or a liver transplant.


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