Why urine may smell like fish (and how to treat)

Urine with an intense fishy smell is usually a sign of fish odour syndrome, also known as trimethylaminuria. This is a rare syndrome that is characterised by a strong fish-like smell in body secretions such as sweat, saliva, urine and vaginal secretions. It causes a lot of discomfort and embarrassment.

Due to the strong smell, people with this condition tend to take baths frequently, change underwear several times a day and they wear very strong perfumes, which in most cases does not help getting rid of the odour. In such cases, the syndrome can best be controlled by avoiding a diet that contains foods rich in trimethylamine such as fish and egg yolk.

Why does this syndrome happen?

This syndrome is due to genetic alteration that causes deficiency in a compound of the organism responsible for the degradation of trimethylamine. This is a nutrient found mainly in fish, shellfish, liver, pea and egg yolk. It causes accumulation of a substance that will be exuded from the body since it evaporates.

Although it is caused by genetic changes, some people may experience this condition when they take drugs that cause the accumulation of trimethylamine, such as Tamoxifen, Ketoconazole, Sulindaco, Benzidamine and Rosuvastatin.

Main symptoms of the syndrome

The only symptom related to this syndrome is the smell of rotten fish that is usually excreted from the body, mainly through body secretions such as sweat, breath, urine and vaginal secretions. Symptoms may appear during childhood when the child is no longer being breastfed and starts to eat normally. It may worsen during adolescence, especially during menstruation as well a when using contraceptives.

Those who have this condition tend to take several baths throughout the day and they constantly change their clothes and in some cases they may avoid living with other people. This is due to embarrassment that happens when the smell is perceived and commented on by other people. For this reason there might be development of psychological problems such as anxiety or depression.

How to confirm the diagnosis

The diagnosis fish odour syndrome is done using a blood test, scraping of the mucous membrane of the mouth or a urine test in order to verify the concentration of trimethylamine, which is responsible for the odour.

How treatment is done

This syndrome has no cure and therefore treatment is done to control and decrease the bad smell. These include reducing the consumption of foods that increase the symptom such as those rich in choline, like fish, shellfish, meats, liver, peas, beans, soy, dried fruits, egg yolk, cabbage, cauliflower, brussels cauliflower and broccoli.

However, it is important to note that pregnant women should not avoid all these foods as some of them, like fish are essential for the development of the baby’s nervous system. It is thus important to take fish even if there is increased smell.

In addition, antibiotics can also be used to control the intestinal flora, so as to decrease the odour. Other tips that can neutralize the smell are using soaps that have a pH between 5.5 and 6.5 (goat’s milk soap), skin creams with pH around 5.0, washing clothes often and taking activated charcoal tablets, according to the medical prescription.