The US Food and Drug Administration (FDA) has issued a new warning this week about the safety of sodium phosphate laxatives available over the counter (OTC) when taken in higher doses than recommended.
Occasional use of OTC laxatives and stool softeners to treat constipation is widespread among both adults and children. Sodium phosphate laxatives work by drawing water into the gastrointestinal tract to help promote a bowel movement. When used in excess, potentially large fluid shifts can occur and cause serious health problems, such as dehydration, disturbances in electrolyte levels (particularly with calcium, potassium, and phosphate), kidney failure requiring dialysis, heart arrhythmias, and even death.
Sodium phosphate laxatives are sold as both oral and rectal preparations (enemas) and are marketed under the brand name Fleet or as store/generic brands (labeled as saline, sodium phosphate, or sodium biphosphate laxatives).
The FDA reviewed data from their Adverse Event Reporting System from 1969-2012 as well as medical literature from 1957-2013 and found 54 cases of serious adverse events in both adults and children, all related to the above complications.
Individuals at highest risk for these serious adverse events were children younger than 5 years, adults older than 55 years, and individuals who have underlying kidney disease or who are taking other medications that may affect kidney function, such as diuretics, certain blood pressure medications, and nonsteroidal antiinflammatory drugs. Furthermore, most adverse events occurred in individuals who took more than the maximum recommended dose of the medication—either more frequently than recommended or in greater amounts than recommended at one time.
The FDA issued the following recommendations to decrease the risk of adverse events related to OTC sodium phosphate laxatives:
- Do not use more than 1 dose in 24 hours, either rectally or orally; if a bowel movement does not occur after a single dose, do not take another dose
- Avoid simultaneous use with any other type of laxative
- Ensure adequate hydration before use
- Do not give rectal products to children younger than 2 years
- Do not give oral products to children younger than 5 years without first talking to a health care professional
- Do not use these products without first talking to a health care professional if you are older than 55 years, have kidney disease or bowel inflammation or obstruction, or take certain medications that may affect kidney function
Prescription versions of sodium phosphate laxatives are also available for precolonoscopy bowel preparation (OsmoPrep or Visicol), and the FDA has previously issued a warning about the higher doses used for this purpose.