Fishy-Smelling Urine: Causes, Symptoms & Treatment

Fishy-smelling urine is associated with an intense, fish-like odor from the genital area from urine and vaginal secretions. It is usually the result of a build-up of trimethylamine in the urine, and can cause great discomfort.

Trimethylaminuria can occur due to genetic factors, certain health conditions (like pregnancy) and even medication use. It can leave patients embarrassed and may prompt frequent showers, strong perfume and frequent clothing changes. 

Although there is no cure, fishy smelling urine and associated odors can be managed with diet changes and medications to manage naturally-occurring flora along the urinary or vaginal tract. Severe odors should be assessed by a doctor to rule out other possible conditions, like a bacterial infection. 

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What causes fishy-smelling urine? 

Fishy smelling urine is typically a result of a condition called trimethylaminuria. Trimethylaminuria is caused by a genetic alteration that leads to a reduced amount of enzymes to breakdown trimethylamine in the body. This nutrient is typically found in fish, seafood, liver, peas and egg yolks. Without this enzyme, trimethylamine can start to accumulate in the body. 

Some people may also experience smelly urine odors from medications, like tamoxifen, ketoconazole, and rosuvastatin. Odors that are noted after starting a new medication should be reported to the doctor. 

Common symptoms

Fishy-smelling urine can often be associated with a fishy odor exuded from the body. It can be noted in body fluids, sweat, breath, exhaled breath and vaginal discharge. Symptoms can be noted from infancy, when babies stop breastfeeding and start consuming solids. It can also worsen with adolescence, especially during menstruation or with the start of birth control. 

People who have trimethylaminuria will usually take frequent baths, switch their clothes and even avoid social situations out of embarassment. This symptom can lead to the development of psychological disorders, like anxiety or depression.

Confirming a diagnosis

Trimethylaminuria is diagnosed through blood tests, a buccal swab and/or a urine test to determine the trimethylamine levels in these specimens. 

Treatment options 

This condition is not curable, and treatment is aimed at managing and reducing fishy odors. This can be done by decreasing intake of foods with high choline levels, like fish, seafood, mead, peas, beans, soy beans, nuts, egg yolks, kale, cauliflowers, brussel sprouts and broccoli.

It is important to remember that pregnant women should not limit certain items in their diet, as fish, for example, is important for fetal development and should be consumed normally. 

Patients may also use antibiotics to control intestinal flora, which may also impact fishy smells. To neutralize odors, the doctor may recommend the use of soaps with a pH between 5.5 and 6.5, goat’s milk soaps, and skin lotions with a pH around 5.0. Frequently washing your clothes and consuming activated charcoal supplements as directed by a doctor may also be advised.