Common side effects related to use of a Fleet enema (sodium phosphate) may include mild abdominal discomfort or cramps, according to WebMD. If persistent diarrhea is present, patients should monitor for signs of dehydration, such as increased thirst, decreased urination, dizziness, wrinkled skin or dry mouth.
Severe or prolonged dehydration may cause damage to the heart or kidneys, so individuals who experience symptoms of dehydration should consult with a doctor, states WebMD. Other more serious side effects that require prompt medical attention may include muscle weakness or spasm, mood changes, severe or persistent stomach pain, bloody stools, rectal bleeding, persistent diarrhea, swelling of extremities or a change in the amount of urine.
Rare but very serious side effects that require immediate medical attention include seizures or abnormal heartbeat, continues WebMD. A severe allergic reaction is another rare but very serious potential side effect. A patient experiencing signs of an allergic reaction, such as rash; swelling of the face, tongue or throat; difficulty breathing; or severe dizziness, should also seek immediate medical attention.
Enemas may be prescribed by a doctor to remove stool from the intestines before surgery or certain bowel procedures, such as a colonoscopy. They may occasionally be used to treat constipation, notes WebMD.