What Are Laxatives? How Do They Work, and What Are Their Uses and Risks?

What Are Laxatives? How Do They Work?

Today, inactivity despite a fast-paced life, and irregular, unhealthy eating slow the digestive system and cause constipation in many of us. Constipation means slow bowel movements and difficulty moving stool through the intestine. Its most common causes are a low-fiber diet, inactivity, insufficient fluids, aging, medications and certain diseases.

In fact, simple steps can help us achieve good bowel health: a healthy diet, adequate water intake and physical activity have positive effects.

3 Factors Against Constipation

Fiber

A diet rich in high-fiber foods can prevent constipation. The Institute of Medicine states that adult women should consume 25 gr of fiber daily and men 38 gr. These amounts are lower for adults over age 50.

Fiber-rich foods include: whole-grain breads, nuts, fresh fruit and vegetables.

There Are 2 Types of Fiber: soluble and insoluble. Insoluble fiber absorbs water, adds bulk in the intestine and helps relieve constipation. Whole grains, wheat bran, carrots and certain other plants are rich in insoluble fiber.

Water

Fiber works best when it absorbs water. It makes stool softer and bulkier, allowing it to move and pass more easily; adequate water intake is necessary for this. Drinking 7-8 glasses of water daily is recommended.

Exercise / Active Living

Regular exercise, such as a brisk daily 30-minute walk, is known to benefit bowel movements.

Although these lifestyle changes help prevent constipation, some people also need medications, or laxatives. Different laxatives have different mechanisms of action, and their effects vary between individuals.

What Is a Laxative Effect?

How Do Laxatives Make the Bowels Work More?

Laxatives act through different mechanisms, increasing bowel motility and stool volume and altering fluid content.

Main Types of Laxatives:

• bulk-forming agents
• osmotic agents
• stimulants
• stool softeners

Bulk-forming agentscontain large, indigestible sugar molecules, giving them water-retaining and bulk-forming properties. They must be taken with plenty of water; otherwise, they may worsen constipation. Bran and psyllium are the most common bulk-forming laxatives.

Osmotic laxativesincrease bowel movements by retaining water and raising osmotic pressure within the intestine because they are not absorbed. They are the fastest-acting laxatives, taking effect within 2-3 hours after oral administration. Common osmotic laxatives include polyethylene glycol, milk of magnesia and lactulose.

Stimulant laxativesmainly work by acting on the nerves stimulating bowel movements. Continuous use may cause low potassium and salt accumulation. Stimulant laxatives include aloe vera, cascara, senna compounds, bisacodyl and castor oil.

Stool softenersincrease fluid content and lubricate stool, allowing it to move more easily with bowel movements. These drugs are generally not the first choice among laxatives. There is insufficient evidence of their effectiveness alone. They are recommended as an addition when other laxative treatments are inadequate. Docusate sodium and docusate calcium are commonly used.

Apart from laxatives, enemasare generally used when other laxatives fail to produce a bowel movement. However, depending on the need for urgent relief or prevention of fecal impaction, they may not always be among the last treatment options.

What Does Research Say About Laxative Use?

Research in Adults

Two systematic reviews and twenty-one studies were analyzed to assess the effects of four different laxatives in adults. Bulk-forming (fiber-based) and osmotic laxatives were found helpful for constipation, but there was little evidence about differences between fiber-based and non-fiber laxatives. Research found that bulk-forming laxatives increased weekly bowel movements by 1-2 compared with placebo and were thought to be better tolerated than other laxatives.

Effects of Laxatives in Children

The effects and side effects of osmotic and stimulant laxatives in children have been examined. One study compared laxatives and placebos in children aged 0-18, totaling 2310 children. Polyethylene glycol-containing, or osmotic, laxatives increased bowel movement frequency and caused fewer side effects than other laxatives. However, stool-softening laxatives are not recommended for children under 6.

What Are the Risks of Laxatives?

Laxative side effects can affect the absorption of certain nutrients, and laxatives can interact with heart and bone medications. Long-term use may reduce colonic motility and worsen constipation. It can disrupt blood electrolyte balances (calcium, chloride, magnesium, potassium and sodium), causing dehydration, kidney damage, abnormal heart rhythms, weakness, confusion (drowsiness), stroke and even death.

Bulk-forming (fiber-based) laxatives have been found safer, including during pregnancy, while stimulants are more harmful by comparison. In 54 cases reviewed by the FDA, over-the-counter sodium phosphate-containing (osmotic) laxatives were found harmful. Among thirty cases examined, they caused the deaths of one child and twelve adults. According to the FDA, recommended doses of sodium phosphate laxatives must not be exceeded, and high-risk patient groups should not use them without consulting a physician.

Laxatives are also not a weight-loss tool and should not be considered for this purpose.

Natural Laxatives

Certain foods help digestion and bowel movements. People with constipation prefer natural laxatives because they believe they have fewer side effects and know what they are consuming. Natural laxatives have not been evaluated in large studies, and generally work through their high fiber content. Examples include aloe vera, chia seeds, flaxseed, green fibrous vegetables, dried apricots, high-fiber fruits such as kiwi, apples and pears, coconut water and probiotic foods. Aloe vera contains a stimulant called anthraquinone and has even been recognized as an over-the-counter laxative drug in the United States. Probiotic foods were found in one study to increase bowel movements and contractions. Hot peppers also have a laxative effect, but are not recommended for hemorrhoids, which often accompany constipation.

Conclusion 

Laxatives used to treat constipation and sluggish bowels, health problems arising for many reasons, are an important healthcare item and a frequently prescribed drug group. The effects of such widely used medications must be well understood. These research reviews concluded that intermittent, careful laxative use is effective and safe. Natural laxatives should also be used with recognition that their exact effects are not understood. Something being natural does not always mean it is best. Natural laxatives need further research, as do the long-term effects of pharmacological laxatives.

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