[citation needed] People with TMAU may have an intermittent fish-like body odor, depending on diet and the severity of their FM03 mutation.

In a study by Wise PM,[4] of 115 positively identified TMAU subjects, after a choline challenge load test (intentionally ingesting a TMA precursor) only 10% expressed a smell at a social distance.

[5] Most cases of trimethylaminuria appear to be inherited in an autosomal recessive pattern, which means two copies of the gene in each cell are altered.

Carriers may have mild symptoms of trimethylaminuria or experience temporary episodes of fish-like body odor.

As the compound is released in a person's sweat, urine, and breath, it causes the strong odor characteristic of trimethylaminuria.

[citation needed] Although lecithin, creatinine and betaine are technically precursors to TMA, pilot studies have shown no significant effect on the production of excess TMA/TMAO in urinary analysis at normal dietary levels of consumption.

Olfactory reference syndrome is a condition where there is a persistent false belief and preoccupation with the idea of emitting an abnormal body odor.

[21][22] Unrelated fecal smells are an often misinterpreted self reported symptom associated with TMAU,[20] Cashman JR[23] found that 53% of TMAU and 59% of non-TMAU subjects suffered from regular halitosis, caused by dental plaque on the back of the tongue, which produced on average "200-600 ppb of sulfurous/fecal smelling volatile sulfur compounds (i.e., VSC: hydrogen sulfide; methylmercaptan; dimethylsulfide) with each exhalation, creating a 'malodorous cloud' in their vicinity".

[citation needed] There is the possibility that someone may suffer from both Trimethylaminuria and ORS-like paranoia, due to the potential lack of ability to smell the odour oneself and the worry that it generates.

It is recommended to organise reliable confidants, colleagues, friends or relatives ("odor buddies"[24]) to work with the sufferer to discretely inform them if they are presenting an odour.

Affected individuals experience shame and embarrassment, fail to maintain relationships, avoid contact with people who comment on their condition, and are obsessive about masking the odour with hygiene products and even smoking.

The malodorous aspect can have serious and destructive effects on schooling, personal life, career and relationships, resulting in social isolation, low self-esteem, depression, paranoid behaviour, and suicide.

This designation, and the fact that the condition is often unrecognised by doctors, misdiagnosed and can have important ramifications including missed or delayed diagnosis.

[citation needed] Ways of reducing the fishy odor may include: Additionally, at least one study[33] has suggested that daily intake of the supplements activated charcoal and copper chlorophyllin may temporarily improve the quality of life of individuals afflicted with TMAU by helping their bodies to oxidize and convert TMA to the odorless N-oxide (TMAO) metabolite.

900mg of trimethylamine,[34] 8g-20g of choline,[35] 3g of carnitine[36] or 20g betatine[37] has been known to cause temporary TMAU-like fish odour symptoms.

Between the years of 1997 and 2017, Sheffield Children's Hospital in England diagnosed several hundred people with TMAU2, and suggested the majority to be caused by dysbiosis in the gut.

[39] There is no reference to scientific research confirming gut dysbiosis alone can cause TMAU2, and this type of diagnosis was not produced at other testing sites.

[citation needed] The 2023 film The Holdovers, directed by Alexander Payne, features a character with trimethylaminuria, although the condition was first described in the year in which the movie takes place.