The Food and Drug Administration (FDA) is warning that some over-the-counter laxatives are potentially dangerous to consumers who don't follow proper dosing instructions or have certain health conditions.
 

In fact, there have been dozens of reports of serious side effects, including 13 deaths, associated with the use of sodium phosphate laxatives, the agency said.
 

Sodium phosphate laxatives should be used as a single dose taken only once a day and should not be used for more than three days, the FDA noted. Consumers who do not have a bowel movement after taking an oral or rectal dose should not take another dose of the product, the agency warned.
 

In addition, labeling instructions note adults and children should consult healthcare professionals before using such products if they have kidney disease, heart problems, or dehydration.
 

Laxatives come in different forms, with different ingredients. The sodium phosphate used in some products is in a class of medications called saline laxatives that promote a bowel movement by drawing water into the bowel, which softens the stool and makes it easier to pass.
 

Laxative products containing sodium phosphates are marketed under the brand name "Fleet" and also as store brands and generic products. All can cause serious side effects, such as dehydration or abnormal levels of electrolytes in the blood that can lead to serious complications, such as kidney damage and sometimes death, the FDA said in its warning.
 

"The bottom line is that these products are safe for otherwise healthy adults and older children for whom dosing instructions are provided on the Drug Facts label as long as they follow these dosing instructions and don't take the product more often, or in greater amounts, than the label instructs," said Mona Khurana, M.D., a medical officer in FDA's Division of Nonprescription Regulation Development and a children's kidney disease specialist.
 

The FDA has identified 54 cases of serious side effects associated with the oral or rectal use of OTC sodium phosphate products for the treatment of constipation in adults and children. Thirteen cases were fatal, including one child and 12 adults.
 

"It is not possible to determine the precise rate of these events as no one knows how many individuals who take these medications may experience side effects," said Khurana. "Not everybody who develops problems in association with sodium phosphate use reports to the FDA."