If you don’t read the over-the-counter laxative information and follow instructions properly before taking doses, you may be in trouble.

The Food and Drug Administration (FDA) released a safety announcement this week that warns consumers of the dangers of over-the-counter sodium phosphate drugs, or certain kinds of laxatives, used to treat constipation. The FDA noted that these drugs can be harmful to the kidneys or heart, and may also lead to death if they are abused or misused.

“Constipation may not be a subject for polite conversation, but it’s a condition that bothers many of us on occasion,” the FDA states in a press release titled, “Use Certain Laxatives with Caution.” In its announcement, the FDA continued, “Consumers and healthcare professionals should always read the Drug Facts label for [over-the-counter] sodium phosphate drugs and use these products as recommended on the label, and not exceed the labeled dose.”

If a person takes more than the recommended dose of laxatives, this could not only lead to severe dehydration, but it can also change the levels of electrolytes in the blood and become harmful to organs. Typically laxatives, which can be taken both orally and rectally, soften the stool in the bowel by drawing water there — this particular class of laxatives is called saline laxatives and incorporates sodium phosphate.

Using these drugs in higher doses than prescribed — even just one single dose higher, or more than one dose per day — could lead to severe dehydration and death. “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,” Dr. Mona Khurana said in the FDA press release. Khurana is a medical officer in the Division of Nonprescription Regulation Development. “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. Not everybody who develops problems in association with sodium phosphate use reports to the FDA.” In the report, the FDA noted that there were 54 cases of adverse side effects, with 13 people who died, after they took doses higher than prescribed.

Some people even attempt to use laxatives as a way to lose weight, though this is a form of laxative abuse and can be dangerous. The illusion that “laxatives are effective for weight control is a myth,” the National Eating Disorders Association says. Most food and calories are already absorbed by the time laxatives can get to work to expel waste, and thus the assumed “weight loss” is actually just water loss that will be replenished the next time you drink water.

The FDA suggests that people who are over the age of 55, or who are dehydrated, have kidney disease, bowel obstruction, or are using kidney medication, may be at the highest risk for complications from taking too high a dose. If you take these laxatives, pay attention to any symptoms, including dehydration, dry mouth, lightheadedness, and drowsiness. Kidney problems caused by sodium phosphate laxatives can cause decreased urine production and swelling of the legs. The FDA urges that if any of these symptoms occur, make sure to seek medical attention as soon as possible. Also, Khurana cautions caregivers to refrain from providing laxatives to children under the age of 2.