Diuretics are a group of drugs given to help the body eliminate excess fluid through the kidneys in order to treat hypertension (high blood pressure), kidney and liver disorders, glaucoma, congestive heart failure (CHF), and idiopathic intracranial hypertension (pseudotumor cerebri), a condition characterized by increased fluid pressure within the blood vessels supplying the brain.
In addition to prescription diuretics, there are several types of diuretics available in over-the-counter formulations or commonplace beverages.
Diuretics have several purposes in mainstream clinical medicine:
The connection between diuretics and dieting is twofold. First, many of the conditions that are treated by administration of prescription diuretics—particularly hypertension, CHF, and idiopathic intracranial hypertension—are more common in obese patients, more difficult to treat in the obese population, or both. Thus weight loss and lifestyle change are commonly recommended to these patients along with prescription diuretics.
The second connection is that many dieters use or abuse diuretics as a means to quick weight loss. Abuse of diuretics frequently coexists with self-induced vomiting and abuse of laxatives in patients with eating disorders. This combination of behaviors is called purging. Purging may occur in some patients with eating disorders as a means to a slender appearance, but it is also common in high school and college athletes participating in such weight-related sports as rowing, wrestling, gymnastics, and long-distance running. Athletes may also abuse diuretics like furosemide (Lasix) in order to mask the fact that they are taking other drugs to enhance performance in competition. People who abuse diuretics may take herbal preparations reported to have diuretic effects or over-the-counter preparations containing caffeine or pamabrom as well as prescription diuretics.
There are five major types of prescription diuretics.
LOOP DIURETICS. Loop diuretics are the strongest of the prescription diuretics. They take their name from the fact that they work in the ascending limb of the loop of Henle, a structure in the kidney in which magnesium and calcium are ordinarily reabsorbed. By disrupting the reabsorption of these two ions, loop diuretics bring about increased urine production, which in turn lowers blood volume, leading to lowered blood pressure. Loop diuretics also cause the veins to dilate, which lowers blood pressure mechanically. This vasodilation is independent of the drug's diuretic effect.
Loop diuretics are usually given to treat edema (accumulation of fluid in body tissues) associated with heart failure; cirrhosis of the liver; impaired kidney function or nephrotic syndrome (a condition in which the kidneys leak protein from blood into the urine); hypertension; or severe hypercalcemia (abnormally high levels of calcium in the blood). They are also given together with other drugs to treat edema of the brain or lungs, conditions that require rapid diuresis. Drugs classified as loop diuretics include furosemide (Lasix), bumetanide (Bumex), ethacrynic acid (Edecrin), and torsemide (Demadex).
THIAZIDE DIURETICS. Thiazide diuretics are derived from a chemical called benzothiadiazene. Unlike the loop diuretics, which work in the loop of Henle, thiazide diuretics work in a different structure called the distal convoluted tubule, although they function in a similar way to increase urine production by decreasing the kidney's reabsorption of sodium and calcium. They are not as strong as loop diuretics and have fewer adverse effects.
Thiazide diuretics are commonly prescribed to manage high blood pressure because they help to dilate blood vessels as well as lower blood volume by increasing urine output. They are also sometimes given to patients with high levels of calcium in the urine to prevent the formation of kidney stones and lower the risk of osteoporosis. They include such drugs as hydrochlorothiazide (HydroDIURIL, Esidrix), chlorothiazide (Diachlor, Diuril), and chlorthalidone (Hygroton, Hylidone).
POTASSIUM-SPARING DIURETICS. Potassium-sparing diuretics include such drugs as amiloride (Midamor) and triamterene (Dyrenium). They are usually given together with loop diuretics in treating CHF or high blood pressure to prevent the patient's potassium level from falling too low. They work by decreasing sodium reabsorption in the collecting tubules of the kidneys.
There are two formulations that combine the potassium-sparing diuretic triamterene with the thiazide diuretic hydrochlorothiazide in one pill—Maxzide and Dyazide—thus simplifying the patient's dosage schedule.
Until early 2007, high-dose mannitol was recommended as treatment to reduce fluid accumulation inside the skull in cases of head trauma, on the basis of randomized trials conducted by a neurosurgeon in Brazil who committed suicide in 2005. His papers on the use of mannitol in head surgery were called into question in late 2006; neither his former coauthors nor the journal editors who published his studies were able to verify his data, and the university he claimed as his affiliation had never employed him.
CARBONIC ANHYDRASE INHIBITORS. Carbonic anhydrase inhibitors are a class of diuretics that increase water loss through the kidneys by changing the acidity of urine. Their most common use, however, is to treat glaucoma by lowering the fluid pressure inside the eyeball. The most common diuretic in this group, acetazolamide (Diamox), is also used as an anticonvulsant (drug given to prevent seizures). Other carbonic anhydrase inhibitors include dichlorphenamide (Daranide) and methazolamide (Neptazane).
Nonprescription diuretics are often used by dieters to flush water from the body in the belief that this practice will promote rapid weight loss. According to the Centers for Disease Control and Prevention (CDC), 1% of adult male dieters in the United States and 2% of adult women have used over-the-counter diuretics as part of weight loss attempts.
CAFFEINE. Caffeine is a xanthine alkaloid found naturally in coffee beans, tea leaves, kola nuts, cocoa beans, and a few other plants. It is well known as a central nervous system (CNS) stimulant, enjoyed in brewed coffee, tea, hot chocolate, cola beverages, and energy drinks. It is also available in tablet form as an over-the-counter stimulant in such compounds as NoDoz. Caffeine is broken down in the liver to three substances, one of which is theobromine, which acts as a diuretic and increases urine volume. Some dieters drink coffee as much for its diuretic effects as for its effectiveness is counteracting the fatigue that often accompanies low-calorie diets.
HERBAL PREPARATIONS. Naturopaths and other practitioners of alternative medicine often recommend certain herbal preparations, including herbal teas, as diuretics available without a prescription. Herbs commonly recommended for their diuretic qualities include uva ursi, dandelion, hydrangea, parsley, butcher's broom, buchu, juniper, horsetail, buckthorn, and asparagus.
ALCOHOL. Beverage alcohol (ethanol) is known to have a diuretic effect; in fact, many of the symptoms of an alcohol hangover, such as headache, nausea, and diarrhea, are related to the dehydration resulting from alcohol intoxication. Many weight-reduction diets (the Mediterranean diet being a notable exception) forbid alcohol because it contains more calories than most people realize—7 calories per gram, in comparison to 9 calories per gram for fat and 4 calories per gram for protein. Some women, however, drink an occasional glass of wine or beer for its diuretic effect, to relieve the discomfort of fluid retention before the onset of their menstrual period.
PAMABROM. Pamabrom is a mild diuretic related chemically to theophylline, one of the breakdown products of caffeine. It is compounded with acetaminophen in a number of over-the-counter (OTC) remedies for premenstrual bloating and backache associated with fluid retention, including New Tylenol for Women, Backaid, and Diurex.
Both prescription and nonprescription diuretics should be used with care.
Prescription diuretics should be used only under a doctor's supervision and monitored in long-term users, as dosage requirements may change or the doctor may recommend dietary supplements to compensate for electrolytes and nutrients lost through the use of some diuretics. In addition, patients should not stop taking prescription diuretics or change the dosage without consulting their doctor.
Nonprescription diuretics can still cause adverse effects even though they are weaker than prescription diuretics.
Prescription diuretics may interact with some other prescription drugs as well as with herbal products:
Nonprescription diuretics, particularly alcohol, may interact with a variety of substances:
Prescription diuretics have a number of side effects:
Adverse effects from nonprescription diuretics may include:
Parents do not ordinarily need to be concerned about children or adolescents abusing prescription diuretics, as these drugs do not produce mood alteration or relieve pain. Adolescents, however, are likely to abuse nonprescription diuretics in relation to eating disorders or athletic competition; one study found that 64% of adolescents diagnosed with eating disorders were using herbal diuretics. A few adolescents may develop caffeine-related disorders apart from eating disorders or sports.
Abuse of over-the-counter diuretics is common among adolescents with eating disorders accompanied by purging, although it is slightly less common than self-induced vomiting or abuse of laxatives. Although eating disorders are classified as mental health problems, they can have serious lifelong digestive and nutritional consequences, including erosion of tooth enamel, loss of bone density leading to eventual osteoporosis, and ongoing problems with water retention.
Numerous reports of diuretic abuse among athletes in high school and college sports programs have accumulated since the late 1980s. Abuse of OTC diuretics is higher among both males and females in such weight-related sports as wrestling and rowing than among participants in sports that do not classify athletes by weight (distance running, swimming, basketball, etc.). More males than females abuse diuretics at both the high school and college levels; the average age of initial misuse of diuretics in one sample was 15.6 years for males and 16.2 years for females. Abuse of diuretics puts young athletes, particularly males, at risk of dehydration, chest pains, fainting, and irregular heart rhythms, particularly when combined with ephedrine or other stimulants.
According to DSM-IV, caffeine use typically begins in the mid-teens in the United States and Canada, with levels of consumption increasing into the early adult years (20s and 30s). Among teenagers, caffeine use is usually higher among boys than girls, and higher among smokers than nonsmokers. Most fatal cases of caffeine overdose occur among adults in their early 20s, usually as a result of taking OTC caffeine tablets by mouth or inhaling crushed tablets.
See also Coronary heart disease ; Eating disorders ; Renal nutrition ; Vinegar ; Vitamin B6 .
American Psychiatric Association. Diagnostic and Statistical Manual of Mental Disorders: DSM-5. Arlington, VA: American Psychiatric Association, 2013.
American Society of Health-System Pharmacists (ASHP). AHFS Drug Information 2018. Bethesda, MD: American Society of Health-System Pharmacists, 2018.
Hoyng, P. F., and L. M. van Beek. “Pharmacological Therapy for Glaucoma: A Review.” Drugs 59, no. 3 (March 2000): 411–34.
Karlson, K. A., C. B. Becker, and A. Merkur. “Prevalence of Eating Disordered Behavior in Collegiate Lightweight Women Rowers and Distance Runners.” Clinical Journal of Sport Medicine 11, no. 1 (January 2001): 32–37.
Kerrigan, Sarah, and Tania Lindsey. “Fatal Caffeine Overdose: Two Case Reports.” Forensic Science International 153, no. 1 (October 4, 2005): 67–69.
Kiningham, R. B., and D. W. Gorenflo. “Weight Loss Methods of High School Wrestlers.” Medicine and Science in Sports and Exercise 33, no. 5 (May 2001): 810–13.
Kruger, J., et al. “Attempting to Lose Weight: Specific Practices among U.S. Adults.” American Journal of Preventive Medicine 26, no. 5 (June 2004): 402–6.
Orbeta, R. L., et al. “High Caffeine Intake in Adolescents: Associations with Difficulty Sleeping and Feeling Tired in the Morning.” Journal of Adolescent Health 38, no. 4 (April 2006): 451–53.
Roerig, James L., et al. “The Eating Disorders Medicine Cabinet Revisited: A Clinician's Guide to Appetite Suppressants and Diuretics.” International Journal of Eating Disorders 33, no. 4 (May 2003): 443–57.
Steffen, Kristine J., et al. “A Survey of Herbal and Alternative Medication Use among Participants with Eating Disorder Symptoms.” International Journal of Eating Disorders 39, no. 8 (December 2006): 741–46.
Thomas, M. C. “Diuretics, ACE Inhibitors, and NSAIDs— the Triple Whammy.” Medical Journal of Australia 172, no. 4 (February 21, 2000): 184–85.
Vertalino, Maggie, et al. “Participation in Weight-Related Sports Is Associated with Higher Use of Unhealthful Weight-Control Behaviors and Steroid Use.” Journal of the American Dietetic Association 107, no. 3 (March 2007): 434–40.
Alliance for Eating Disorders Awareness. Diuretics.” http://www.allianceforeatingdisorders.com/diuretics (accessed March 26, 2018).
Mayo Clinic staff. “Diuretics.” MayoClinic.com . http://www.mayoclinic.com/health/diuretics/HI00030 (accessed March 26, 2018).
Academy of Nutrition and Dietetics, 120 South Riverside Plz., Ste. 2000, Chicago, IL, 60606-6995, (312) 899-0040, (800) 877-1600, firstname.lastname@example.org, http://www.eatright.org .
American College of Sports Medicine, 401 West Michigan St., Indianapolis, IN, 46202-3233, (317) 637-9200, Fax: (317) 634-7817, http://www.acsm.org .
U.S. Food and Drug Administration, 10903 New Hampshire Ave., Silver Spring, MD, 20993-0002, (888) INFO-FDA (463-6332), http://www.fda.gov .
Rebecca J. Frey, PhD