Laxative Abuse: Complications from the Misuse of Laxatives & Diuretics

Laxative & Diuretic Abuse in Eating Disorders

Laxative and diuretic misuse are two common purging methods used by those with eating disorders, particularly those with bulimia nervosa and the binge-purge subtype of anorexia nervosa. Eating disorder patients constitute the largest group of individuals who misuse laxatives, with up to 75% of those with anorexia and bulimia misusing laxatives and approximately 33% misusing diuretics. 

Patients take laxatives to compensate for food intake, prevent weight gain or to alleviate guilt after bingeing. Diuretics are used to achieve a similar result by producing more urine to help eliminate water and achieve a lower body weight.

Athletes are another population that frequently use laxatives and diuretics. Athletes who participate in weight-dependent sports may also abuse laxatives and diuretics to achieve lower weights with the intent to have a competitive advantage.

Laxative & diuretic abuse can cause serious side effects

Stimulant laxatives are typically used by individuals with eating disorders to stimulate the muscle of the gut to produce a bowel movement. Initially, an individual with an eating disorder might use laxatives to treat constipation or any number of other gastrointestinal complications that are caused by low food intake and dehydration. However, over time the misuse of diuretics and laxatives can lead to a variety of issues ranging from dependency on these medications to complications that affect entire organ systems.

Laxative dependence

Laxative abuse is often considered an addiction-like behavior. A patient who abuses stimulant laxatives can become both psychologically and physiologically dependent on them, which can cause unpleasant and uncomfortable symptoms when use stops.

Hypokalemia

Many of the severe medical complications of an eating disorder stem from electrolyte disturbances. Laxative misuse can result in chronic diarrhea, which in turn can cause fluid loss and hypokalemia (low potassium), due to the high potassium in stool water and due to hormonal changes resulting from the intravascular depletion. Hypokalemia can cause:

• Neuromuscular dysfunction
• Gastrointestinal dysfunction, such as ileus and constipation
• Cardiac arrhythmias
• Inability of the kidneys to concentrate urine
• Sudden death

Hyponatremia

One of the main causes of hyponatremia is hypovolemia, which can result from the overall increased water loss stemming from diuretics and laxatives. Excess water consumption is also sometimes used to induce vomiting and can precipitate dangerous drops in sodium.

Central pontine myelinolysis (CPM)

Anyone that undergoes a rapid rise in serum sodium is at risk of developing central pontine myelinolysis, including those with eating disorders and those who misuse diuretics. CPM develops when the medical correction of hyponatremia occurs too abruptly, causing various fluid shifts within the brain. Symptoms typically appear 2-3 days after hyponatremia is corrected, including:

• Changes in cognition
• Dysarthria (trouble speaking)
• Mutism or dysphagia (trouble swallowing)

Within 1-2 weeks, other symptoms may manifest, including:

• Impaired thinking
• Weakness or paralysis in the arms and legs
• Stiffness
• Impaired sensation or loss of coordination

In the most severe cases, CPM can lead to coma or death. There are no proven methods of treatment of CPM outside of supportive treatments, thus the need to avoid development of this complication in the first place. The actual mechanism by which CPM occurs is not fully understood, but the rapid increase in sodium concentration pulls water from brain cells, which destroys myelin and sometimes the nerve cells themselves.

Metabolic alkalosis

Metabolic alkalosis can occur as a result of either laxative or diuretic misuse, although laxative abuse itself can cause a significant loss of bicarbonate in the stools and cause a metabolic acidosis. When the body becomes dehydrated, up-regulation of a hormone called aldosterone occurs. Aldosterone causes more acid to be secreted in the urine, which throws off the body’s acid-base balance and creates more base (i.e. metabolic alkalosis).

Hypokalemia, which can result from diuretic and laxative abuse, can also cause hydrogen ions to shift into the body’s cells (in exchange for potassium), which will also throw off the acid-base balance and contribute to a metabolic alkalosis. Metabolic alkalosis alone is generally asymptomatic, but may cause respiratory and neurologic changes.

PseudoBartter syndrome

Purging behaviors with use of laxatives or diuretics can cause dehydration due to the fluid loss and subsequent PseudoBartter syndrome. A loss of fluid can cause an up-regulation of certain hormones in the body, including aldosterone. The same hyperaldosteronism that maintains intravascular volume and lessens the risk of fainting also causes salt and water resorption in the kidneys, contributing to the edema formation during refeeding.

Hypomagnesemia

Increased aldosterone can also cause magnesium wasting in the urine, thereby contributing to hypomagnesemia (low magnesium). A small amount of magnesium is lost through vomiting, although larger amounts of magnesium can be lost through laxative abuse given the higher magnesium concentration in lower gastrointestinal secretions. Diuretics are also associated with magnesium loss in the urine. Hypomagnesemia can cause:

• Abnormal muscle contraction
• Cramping
• Cardiac arrhythmias
• Generalized weakness

Kidney disturbances

Prolonged laxative abuse and purging behaviors associated with development of hypokalemia are associated with chronic kidney disease. Renal function can be reduced through a combination of laxative abuse-induced volume depletion, hypokalemia, rhabdomyolysis and hyperuricemia (excess of uric acid in the blood). Repeated bouts of hypokalemia can contribute to hypokalemic nephropathy, which may be irreversible and lead to chronic kidney disease or hemodialysis.

Cathartic colon

Chronic stimulant laxative misuse can result in the colon becoming inert and unable to push stool forward. Use of these stimulant laxatives damages one of the nerve layers of the intestine, causing the aperistalsis, which then creates a need for even greater amounts of stimulant laxatives. This condition is believed to resolve over time with discontinuation of the stimulant laxative use.

Treatment for laxative & diuretic misuse

Treatment for laxative and diuretic misuse are very similar, often involving patient education and addressing psychological dependency. Treatment is primarily psychological and targeted toward addressing a patient’s psychological dependency on these substances and how that relates to their eating disorder.

Stopping laxative and diuretic abuse will look a lot like treatment for an eating disorder. The care a patient receives will depend on the severity of complications and dependency on laxatives or diuretics. Letting go of a medication and behaviors associated with its misuse can be difficult and may require psychological guidance to overcome psychological dependency and address thought patterns that reinforce laxative and diuretic misuse.

Education on bowel function

Education is an essential tool in helping a patient stop misusing laxatives and/or diuretics, however, it can be challenging to convince patients to stop using them. Due to the nature of eating disorders, a patient may not only be physically dependent on laxatives for bowel function but might also be psychologically dependent on laxatives and diuretics due to their anxiety about weight gain.

Clinicians should educate patients on the range of normal bowel function, which includes a minimum of three bowel movements per week as defined by the Rome IV criteria. It’s also important to emphasize that laxatives are not an effective means of weight loss as most caloric absorption occurs in the small intestine and not in the colon, where laxatives function. The effect on nutrient absorption is minimal, with only about a 12% reduction with use of laxatives.

Interventions for laxative/diuretic dependency

The only treatment for laxative and diuretic misuse is cessation. There is no medical benefit to tapering off laxatives, as continued exposure may cause further damage to the nerves and contribute to cathartic colon.

When a patient is dependent on laxatives, they may also experience constipation. If constipation lasts for more than three days, a short course of a non-stimulating laxative combined with oral fluids should be used to promote a bowel movement. Daily polyethylene glycol, an osmotic laxative taken by mouth, should be started as soon as the patient stops taking stimulating laxatives. In some instances, stronger laxatives may need to be used but this should only be done while monitored under a doctor’s care.

Unlike laxative dependency, physical dependency on diuretics is rare. However, a similar approach to treating laxative misuse should be taken regarding the psychological dependency a patient might have with diuretics and their relationship with these medications. Patients should be educated on the difference between water weight and weight from muscle or fat and the importance of adequate hydration.

References

• Bulik CM. Abuse of drugs associated with eating disorders. J Subst Abuse 1992;4:69-90. 
• Bo-Linn GW, Santa Ana, CA, Morawski SG, et al. Purging and calorie absorption in bulimic patients and normal women. Ann Intern Med 1983;99:14-7.
• Forney KJ, Buchman-Schmitt JM, Keel PK, Frank GK. The medical complications associated with purging. Int J Eat Disord 2016;49(3):249-59.
• Gibson D, Benabe J, Watters A, et al. Personality characteristics and medical impact of stimulant laxative abuse in eating disorder patients---a pilot study. J Eat Disord 2021;9(1):146.
• Marino JM, Ertelt TE, Wonderlich SA, et al. Caffeine, artificial sweetener, and fluid intake in anorexia nervosa. Int J Eat Disord 2009;42(6):540-45.
• Mehler PS and Andersen AE (eds). 2022. Eating Disorders: A comprehensive guide to medical care and complications, 4^th ed. John Hopkins University Press.