Galactosemia is a rare, inherited genetic disorder in which the blood has an elevated level of galactose, which is a sugar found in dairy products. Galactosemia is caused by a deficiency in one of the three enzymes needed to break down galactose.

A child who has galactosemia appears normal at birth but develops symptoms upon taking formula or breast milk. Symptoms of galactosemia include:

• Loss of appetite.
• Vomiting.
• Diarrhea.
• Poor weight gain.

Without early diagnosis and treatment, a child with galactosemia can develop mild to severe effects. The child may stop developing normally and may have vision problems (cataracts), liver problems, and mental retardation. One form of the disease causes cataracts without mental retardation and poor growth.

Galactosemia is treated with a special diet that does not contain galactose. A person with galactosemia must avoid milk and milk products for life.