Breast-feeding mothers should not take the drug domperidone to boost milk production because it may put them at risk of serious heart problems and sudden death, the U.S. government warned Monday.
Domperidone is touted on the Internet as a safe way to stimulate milk production because it may increase the amount of lactin, a hormone needed for lactation.
The drug is not approved in the U.S. but is sold in other countries in intravenous and oral forms to treat stomach disorders.
The Food and Drug Administration said domperidone posed serious risks and was not approved in any country for enhancing milk production.
Some people in other countries who were treated with the intravenous version have experienced irregular heartbeats or cardiac arrest, or died suddenly, the FDA said.
In many countries, the oral form of domperidone comes with a warning that the drug is excreted in breast milk and the risks to breast-feeding infants are unknown, the FDA said.
The FDA said some women in the United States had obtained domperidone from "compounding" pharmacies that prepare medicines for patients from bulk ingredients or from foreign sources.
The agency sent warnings to six pharmacies and firms that it said were supplying domperidone to tell them the sales were illegal.
Regulators also alerted border inspectors to watch for attempts to import domperidone and told them to confiscate the drug if they find it.