Laxative abuse is found in individuals suffering from eating disorders. In addition, the elderly population and others may unintentionally abuse laxatives unaware of the side effects. Hence it is important to recognize the intake of this group of medications and include it on differential when patients complain of diarrhea.
Excessive use of laxatives causes abnormal bowel habits such as large frequent bowel movements that can even occur nocturnally. These can be very watery due to the inadequate absorption of water. The presentation includes electrolyte and mineral imbalances. It is important to recognize that the body has specific requirements for sodium, potassium, magnesium, and phosphorous. These are utilized for nerves and muscles especially the heart. Thus a disturbance in the balance can produce critical outcomes such as cardiac arrhythmias, which stem from marked hypokalemia. Dehydration is another profound finding which can result in malaise, weight loss, impaired vision, tremors, and organ damage. Rehydration is crucial as this is potentially fatal.
In patients who use laxatives chronically, dependency is seen as the colon needs increased amounts of laxatives to respond. Further issues with chronic use is the loss of normal functions which can lead to constipation, or "reflex constipation". Complications of abuse include infection of the colon and irritable bowel syndrome (IBS). Also hepatic damage can occur albeit rarely. Chronic intake may be associated with colonic cancer risk.
A thorough history and physical is essential. Also the clinician should exclude other causes of chronic diarrhea. In all patients, especially the elderly, it is pertinent to screen for all medications.
Laboratory studies includes complete metabolic panel to assess for electrolytes and minerals. Also these will help the clinician to identify acid base disorders. Other tests include a complete blood count (CBC) and a stool culture to rule out infections when still in the initial phases of workup.
Urinalysis with titers for magnesium, phosphate, bisacodyl, senna, and cascara to detect laxative products. However, be aware that certain assays have not been reliable . Further urine studies include urine volume and electrolytes to determine the volume status and the degree of dehydration. Finally, stool studies investigating the amount of sodium and potassium, pH, and laxative titers are also useful.
Discontinuation of the laxative(s) and restoration of normal gastrointestinal functions are key. A detailed discussion with the patients to ascertain their thoughts and attitudes regarding what regularity of bowel movements means is necessary. In addition, educating patients regarding normal bowel function and habits is important to help them avoid further abuse.
Since patients may have an underlying eating disorder, this should be addressed. Long term psychotherapy should be established. Individuals suffering from eating disorders are apprehensive about discontinuing intake of laxatives due to the possible water retention and weight gain. This warrants a discussion on the effects of the medicine and the aftermath of discontinuation. Patients with chronic constipation should be evaluated for underlying diseases and conditions. Hence, treating the etiology may improve constipation overall.
There are treatment regimens outlining how to discontinue the intake of laxatives. One study  closely supervised a withdrawal regimen that consisted of discontinuing of all laxatives but replaced them with docusate, psyllium, fruit lax, and other natural foods. A combination of Magnolax and cascara was also prescribed. Furthermore, patients were provided with education about healthy diets and gastrointestinal habits. Of the 7 patients who completed the study, 5 reduced their laxative intake by 50%.
Another protocol  called for stopping laxatives abruptly and immediately in which patients utilized non laxative therapies such as bulk forming liquids, stool softeners, and gylcerin suppositories for bowel function, in addition to education. There was success in 57% of patients who were able to abstain from laxatives.
The long term prognosis of these patients is not known. There are no studies regarding follow up on individuals abusing laxatives. A minority of patients discontinue laxatives. However, most continue usage of these medications chronically and are likely to develop lifelong effects. Individuals with eating disorders may not disclose the laxative habit which can delay the diagnosis and treatment.
Excessive use of laxatives results in osmotic or secretory diarrhea. Osmotic diarrhea is due to agents such a magnesium sulfate, sodium phosphate, or nonabsorbable sugars. Secretory diarrhea is secondary to use of bile salts, castor oil, or docusate.
There are unintentional excessive users such as those with chronic constipation or those who do not have understanding of what normal bowel habits are. An important etiological factor is the psychiatric component of the abuse. Patients with eating disorders such as bulimia nervosa and anorexia nervosa commonly use laxatives. In addition to eating disorders, there are other associated psychiatric disorders including depression, anxiety, borderline personality, suicidal behaviors and Munchausen Syndrome with or without proxy.
General population: The lifetime occurrence of laxative abuse is 4.18% .
Studies investigating laxative abuse in eating disorders are dependent on self reporting. This limits the accuracy. In addition, literature uses varied definitions of what laxative abuse constitutes. Therefore, the true data is not fully established. Nevertheless, there are studies that have investigated the prevalence among different groups.
Bulimia nervosa: The lifetime occurrence in those suffering from this disease is approximately 15% . This number conflicts with other studies in which the prevalence is estimated to range from 18% to 75%   . One study  found that 36% of the bulimic patients in the study used excessive amounts of laxatives for weight control. Another study reported 67% of bulimic subjects abused laxatives to eliminate consumed food and weight control . In addition, the prevalence between various eating disorders may differ. One study explored two eating disorder groups: 1) eating disorder not otherwise specified, purging type and 2) bulimia nervosa, the purging subtype. 86% of individuals in group one abused laxatives versus 38% in group two .
Anorexia nervosa: One study investigated the use of laxative by two modes, self reporting and urinalysis studies. The researchers demonstrated a prevalence of 12% in patients with self reporting and 19% in patients with both self reporting and urinalysis .
Constipation: This is very common in the elderly as exhibited by prevalence of 50%. This number is actually greater in nursing homes   . Since many patients use over the counter laxatives to treat their constipation, they do not seek medical treatment. So the numbers of constipated individuals using laxatives are not fully established.
Overall, the prevalence of laxative abuse is difficult to elucidate because this condition is underdiagnosed and underidentified. Sometimes it is a diagnosis of exclusion  .
The mechanism of action of laxatives occurs at the large bowel hence disturbing the absorption of water and electrolytes. Note that nutrients and fats are absorbed in small bowel before the food contents reaches the large intestine.
Excessive intake of laxative agents causes diarrhea, which has consequences such as severe imbalance in electrolytes and hypovolemia. Hypokalemia in chronic diarrhea leads to inhibition of bicarbonate secretion and therefore produces metabolic alkalosis. Hypovolemia in acute diarrhea can result in metabolic acidosis. These manifestations are potentially life threatening.
There is a reported case of congestive heart failure (CHF) in a 60 year old woman who presented with hypokalemia (potassium 2.6 mmol/L) and malaise. Her list of active medications included phenolphthalein and rhubarb. Potassium replacement was initiated and laxatives were discontinued. Edema, weight gain, dyspnea all emerged over the next 10 days. She developed CHF as evidenced by symptoms and chest X-rays. The patient was subsequently treated with loop diuretics and a beta blocker and recovery occurred over the following 2 weeks.
In the above case, the clinical picture is due to sodium and water loss secondary to diarrhea. This volume depletion caused and activation in the renin and aldosterone (secondary hyperaldosteronism) system. Hence the water retention that was observed in CHF.
Laxative abuse is observed in individuals seeking weight loss due to the misconception that these medications eliminate caloric intake. This is also prevalent in patients suffering from eating disorders such as bulimia nervosa and anorexia nervosa or self-treating their constipation. Furthermore, many hold incorrect perceptions regarding normal bowel function and habits and thus believe they need laxatives to maintain regularity.
The exact prevalence of laxative use and abuse is not fully established since this diagnosis is underidentified. Also many people self medicate their constipation and therefore these numbers are not documented.
Regardless of the reason people choose to abuse laxatives, the effects can be devastating. The resultant diarrhea can cause severe electrolyte and mineral imbalance. Subsequently, this leads to the impairment of the normal physiology.
Laxative abuse should be on the list of differential diagnoses in all patients with diarrhea, especially in the elderly and individuals suspected to suffer from psychological disorders. Hence, reviewing the list of medications should be a step in the evaluation as well.
Treatment includes discontinuation of the medication. In patients with eating disorders, psychiatric evaluation and treatment is necessary for their overall well being. Patient education regarding normal bowel habits, side effects of laxatives, and alternatives should be a component of patient management.
Laxative abuse is common among people seeking to lose weight and those taking over the counter laxatives for self diagnosed constipation. There is a common misconception that laxatives help with weight loss.
Laxatives work in the colon, or the lower digestive tract. By the time food reaches the lower digestive tract, all the nutrients and facts have already been extracted from the body. The calories are absorbed. Therefore, laxatives do not reduce calories or weight, they cause loss of water, sodium, potassium, and other very important substances required by the body.
There are medical complications such as dehydration, electrolyte imbalance (this is due to diarrhea), heart problems, blood loss in the stool, and even constipation (due to the colon losing ability to function properly).
There are recommendations to prevent constipation: