Factsheet: Fish odour syndrome

Find out more about the condition that leaves its sufferers with a pungent odour.

Fish odour syndrome

What is fish odour syndrome?

Trimethylamiuria (TMAU), or as it is more commonly known, Fish odour syndrome, is a rare inherited condition that affects around 1 in 10,000 people. Sufferers are afflicted with a strong odour due to the fact their bodies are unable to break down a chemical produced naturally by intestinal bacteria called trimethylamiuria. As a result, trimethylamiuria builds up and is released through the person’s sweat, breath and urine giving off a strong fishy odour.

What are the symptoms?

Those who are affected by this condition typically appear healthy and the most obvious symptom is the smell that is released through sweat, urine, reproductive fluids and breath. Some sufferers will have a permanent strong odour but most have a moderate smell that varies in intensity over time and this can be due to a number of factors including diet, stress levels and hormonal changes. Fish odour syndrome appears to affect more women than men and scientists believe that female sex hormones such as progesterone or estrogen aggravate the symptoms. Many women have reported that the odour can increase around the time of menstruation.


You may not be surprised to learn that people who are afflicted with trimethylamiuria often suffer social exclusion which inevitably leads to negative psychological effects such as depression, anxiety and low self esteem. Fish Odour Syndrome can be a truly devastating and permanently frustrating condition to live with. In severe cases some sufferers have experienced aggressive behaviour or suicidal thoughts.

Dr Luis Sierrasesumaga, director of the Department of Paediatrics at the Clinic University of Navarra, North Spain, says: "The problem can be so serious that some patients can get to their teens without stepping out of their homes because of rejection. A number of victims choose jobs where they have to be on their own (and) some smoke a lot to disguise the smell."

Is there a cure?

Unfortunately there is no known cure for trimethylamiuria and even if you showered ten times a day, you would never be able to completely eliminate the body odour. It has however been suggested by many experts that a change in diet can alleviate the symptoms. They advise a diet that is low in choline and therefore sufferers should avoid certain foods such as salt water fish, egg yolks, peas, liver, kidneys and legumes. Nevertheless, as choline is found in many different types of food it can be an incredibly restrictive diet so anyone seriously considering following it should first consult their GP.

Other people who suffer with trimethylamiuria have also found that taking low doses of certain antibiotics, activated charcoal, laxitives or copper chlorophyllin can help, but again anyone wanting to try any of these routes should seek advice from their doctor.

Think you might have trimethylamiuria?

If you are concerned that you might have fish odour syndrome, you should first visit your GP to explain your concerns and symptoms. They may refer you for a urine test or blood test to look for the dysfunctional enzyme that causes trimethylamiuria. As this is a condition that is still fairly uncommon, it may take a while to be diagnosed and the assessment can be inaccurate.