Fish Odor Syndrome
(Trimethylaminuria)

*Fish odor syndrome (trimethylaminuria) facts Medically Edited by: Charles P. Davis, MD, PhD

• Fish odor syndrome (trimethylaminuria) is a genetic disease; symptoms are often present from birth.
• Fish odor syndrome is characterized by an offensive body odor and the smell of rotting fish due to the excessive excretion of trimethylaminuria (TMA) in the urine, sweat, and breath of affected individuals.
• Fish odor syndrome is caused by mutations in the FMO3 gene.
• Other causes of odor body can occur as a result from an excess of proteins in the diet, or from an increase in bacteria that normally produce trimethylamine in the GI tract (also may make fish odor syndrome worse); liver disease, kidney disease, poor hygiene, gingivitis, and cases of blood-borne halitosis. Diagnostic tests that help differentiate fish odor syndrome (trimethylaminuria) from other causes of body odor are available at specialized laboratories.
• Fish odor syndrome symptoms have been seen temporarily in a small number of premature infants and in healthy women at the start of menstruation, usually in individuals that are heterozygous for the mutant FMO3 gene or due to immaturity of the faulty FMO3 gene expression (FMO3 expression increases with age).
• Fish odor syndrome treatment includes certain dietary restrictions, use of acid lotions and soaps to remove secreted trimethylamine on the skin, use of activated charcoal and copper chlorophyllin, certain antibiotics, laxatives, and riboflavin supplements.