Miniature laundry detergent packets arrived on store shelves in recent months as an alternative to bulky bottles and messy spills. But doctors across the country say children are confusing the tiny, brightly colored packets with candy and swallowing them.

Nearly 250 cases have been reported this year to poison control centers. Though they remain a tiny fraction of the thousands of poisoning calls received every year, doctors are concerned. The symptoms they see in connection with ingesting the packets - such as nausea and breathing problems - are more severe than typical detergent poisoning. No deaths have been reported.

"We're not quite sure why it's happening," said Dr. Kurt Kleinschmidt, a Dallas toxicologist and professor at the University of Texas Southwestern Medical Center. "But we've clearly had some kids who have become much more ill. We look at these pods as being clearly more dangerous than the standard detergent."

Tide, Purex and other detergent manufacturers introduced different versions of the packets earlier this year. The lightweight, colorfully swirled plastic packets contain a single-use amount of detergent that dissolves in water. They're intended to be dropped into a laundry machine in place of liquid or powder detergent.

Several poison control centers started to get calls from parents about the packets in March and April, soon after they were introduced in earnest. Texas reported 71 instances of exposure this year, all but one in March or later. Missouri reported 25 cases related to the packets, and Illinois reported 26.

"If you look at the Tide Pods, they're bright blue and bright red and they look very similar to some of the ribbon candy," said Julie Weber, director of the Missouri Poison Control Center in St. Louis.

Paul Fox, a spokesman for Cincinnati-based Procter & Gamble, the parent company of Tide, says all cleaning products need to be handled carefully. He said Tide was working with poison control centers and advocacy groups to make sure parents know more about the risks.

"The packs themselves are safe, regardless of who manufactures them, provided that they are used for their intended purpose," Fox said. "The risk becomes when they're left like any other household product within reach of small, inquisitive hands."

While the detergent packets are a threat, poison control centers receive far more reports about other substances annually. In 2010, they fielded thousands of calls about potential poisoning to children under 5 from ibuprofen, diaper rash cream and other household substances.

However, doctors are alarmed about the packets because they appear to be more dangerous than just swallowing liquid or powder detergent.

Dr. Michael Buehler of the Carolinas Poison Center said there were several possible reasons why, including that the packets carry a full cup's worth of detergent in bite-size form or the detergent in the packet might activate more quickly or differently.

"The children get sicker, more severe, and they do this quicker than what we've seen with standard liquid laundry exposure," Buehler said.

In suburban Philadelphia, a 17-month-old boy was home with his mother when she "turned her back for the proverbial second," said Dr. Fred Henretig of the Poison Control Center at The Children's Hospital of Philadelphia. The boy climbed up on a dresser and popped a detergent package in his mouth, Henretig said.

The boy vomited, became drowsy and started coughing. He was eventually put on a ventilator for a day and hospitalized for a week, Henretig said.

Poison control centers in several states have issued or are preparing warnings for local emergency rooms and parents. Washington state poison control center development director Terri Suzuki said her center has faxed alerts to emergency rooms and posted about the capsules on its Facebook page.

The Indiana Poison Control Center was expected to advise parents in coming days about the packets' risk. One child near Fort Wayne, Ind., tried to eat a packet and nearly had to be placed on a ventilator, said Dr. Brent Furbee, medical director of the Indiana Poison Control Center. Furbee did not know the child's age.

Detergent packets are common in Europe, but are a recent addition to the American market, Fox said. He said Tide Pods had done well against other detergent packets, but it was too soon to say if shoppers appeared to be replacing liquid and powder detergent with the packs.

Kiem Ho, vice president for marketing at Purex, whose consumer goods division is based in Scottsdale, Ariz., said its UltraPacks packaging comes with warning labels to keep out of reach of children.

"This is a new form of laundry product and we will continue to join other manufacturers to safeguard and educate consumers on the correct storage and use of these products in the home" Ho said in a statement.