Sinus infections may cause more than 20 percent of all cases of toxic shock syndrome in children, U.S. researchers said Monday.

They said doctors treating children for toxic shock syndrome should be aware of the risk.

"Prompt imaging studies of the sinuses is mandatory when no apparent cause of toxic shock syndrome is found," Dr. Kenny Chan of the University of Colorado and the Children's Hospital of Denver, whose study appears in the Archives of Otolaryngology, said in a statement.

Chan said most people associate toxic shock syndrome with tampons used by menstruating women but it can affect men and children, too. It is caused by toxins produced by bacteria, and can cause fever, rash, low blood pressure, and in rare cases, death.

While some cases had been seen after sinus surgery, little is known about sinus infections as a cause, particularly in children.

Chan and colleagues analyzed the medical records of 76 children who had toxic shock syndrome between 1983 and 2000.

They found 23 also had either acute or chronic sinus infections. Sinus infections were the primary cause of toxic shock in 21 percent of the cases — many of which were serious. Ten of the children were admitted to the intensive care unit, four needed drugs to raise their blood pressure and six needed surgery.

"It is imperative that physicians, particularly those who are providing intensive care to children, recognize that rhinosinusitis can be the sole cause of toxic shock syndrome in children," Chan and colleagues wrote.