Laxatives: Lowering Blood Pressure?

Laxatives are drugs that relieve constipation by loosening stools or inducing a bowel movement. They are available in many forms, including pills, capsules, liquids, suppositories, and enemas. While laxatives are generally considered safe, they can have side effects such as increased constipation, throat irritation, and severe cramps or pain. They may also interact with other medications, including heart medications and antibiotics. It is important to drink plenty of fluids when taking laxatives to stay hydrated and prevent dehydration.

Laxative suppositories are a type of laxative that is inserted rectally to soften the stool and trigger intestinal contractions. While there is limited direct evidence that laxative suppositories can reduce blood pressure, one study found that inhibition of intestinal sodium absorption, which can be achieved through the use of laxatives, reduced systolic blood pressure in hypertensive rat models. This suggests that laxative suppositories may have a potential indirect effect on blood pressure reduction by reducing sodium absorption in the intestines. However, more research is needed to confirm this effect in humans.

High blood pressure and constipation

High blood pressure, or hypertension, and constipation are two conditions that can sometimes occur together and influence each other. Constipation can be defined as having fewer than three bowel movements a week and facing difficulty in passing stools. On the other hand, hypertension is characterised by elevated blood pressure, which is a major risk factor for cardiovascular diseases, including stroke, heart failure, and coronary heart disease.

The Link Between High Blood Pressure and Constipation

The gut plays a crucial role in influencing the development of hypertension and the effectiveness of antihypertensive medications. The gut microbiota, or the community of microorganisms in the gut, has been found to impact the pathophysiology of hypertension and the regulation of the sympathetic nervous system.

One mechanism linking hypertension and constipation is through intestinal sodium absorption. High intestinal sodium absorption is one of the causes of hypertension, and it also contributes to constipation by reducing faeces water content. Inhibiting intestinal sodium absorption has been shown to reduce blood pressure and increase faeces water content, which can help alleviate constipation.

Additionally, constipation can lead to an increased risk of cardiovascular events, which are triggered by a sudden rise in blood pressure. Straining during bowel movements can cause a significant increase in blood pressure, which may trigger cardiovascular events such as congestive heart failure, arrhythmia, acute coronary disease, and aortic dissection.

Therapeutic Interventions

Therapeutic interventions aimed at improving constipation through the use of laxatives or lifestyle modifications may help stabilise blood pressure variability and potentially reduce the risk of cardiovascular events. However, it is important to consult a doctor before using laxatives, as overuse can lead to a dependency on them. Additionally, certain antihypertensive medications, such as calcium channel blockers and diuretics, can cause constipation as a side effect.

Further studies are needed to establish a direct causal relationship between constipation and cardiovascular disease and to determine the effectiveness of interventions targeting constipation in reducing cardiovascular risk.

Laxatives and medication interactions

Laxatives are available over the counter, but they are not without risks. They can interact with certain medications, including heart medications, antibiotics, and bone medications. It is important to ask your doctor or pharmacist about potential interactions with other medications you are taking.

For example, there are 223 drugs known to interact with Dulcolax Laxative (bisacodyl), with one of these interactions being minor and the other 222 being moderate. Similarly, Gentle Laxative (bisacodyl) is known to interact with 224 drugs, with 223 moderate interactions and one minor interaction.

Additionally, frequent or long-term laxative use can worsen constipation if it is caused by another condition such as diverticulosis. This is because overuse of laxatives can lead to a loss of muscle and nerve response in the intestines, resulting in dependency on laxatives for bowel movements. Bulk-forming laxatives are an exception and are safe to take daily.

It is important to be cautious when taking laxatives and always consult a healthcare professional if you are unsure.

Laxative abuse

Laxatives are commonly used to treat constipation and are available over the counter without a prescription. They work in several ways, including:

• Stimulant laxatives, which increase the speed of movement in the bowels.
• Osmotic laxatives, which draw water into the colon to make passing stool easier.
• Stool softeners, which reduce the texture of stools.
• Bulk-forming laxatives, which prompt normal intestinal muscle contraction by absorbing water to form a soft, bulky stool.
• Suppositories, which are taken rectally and soften stool.

Despite their intended use, laxatives are sometimes misused or abused, particularly by those with eating disorders, those who are middle-aged or older, and athletes. Laxative abuse can have serious health consequences, including:

• Electrolyte imbalances and acid/base changes that can affect the renal and cardiovascular systems and may become life-threatening.
• Fluid loss, which activates the renin-aldosterone system, leading to oedema and acute weight gain when the laxative is discontinued.
• Dehydration and diarrhoea, which can further disrupt the body's electrolyte balance.
• Intestinal paralysis and nerve damage, which can cause long-term digestive problems.
• Increased risk of urinary tract infections and colon cancer.

Laxatives and pregnancy

Constipation is a common issue during pregnancy, affecting up to 38% of pregnant women. Hormonal changes, reduced physical activity, and increased vitamin supplementation can all contribute to this issue. While increasing fibre and fluid intake, as well as regular exercise, are recommended as the first line of treatment, these methods may not always be effective. In such cases, laxatives can be considered as a second-line treatment option.

Types of Laxatives

• Bulk-forming laxatives add fibre to the digestive process, helping the intestines absorb water and form larger, softer stools that are easier to pass. Examples include calcium polycarbophil (FiberCon) and psyllium (Metamucil).
• Stool softeners, such as docusate (Colace), moisten the stool, making it easier to pass. Docusate is generally considered safe during pregnancy but is recommended only for short-term or occasional use.
• Osmotic laxatives, like polyethylene glycol (Miralax), work by keeping water in the intestines instead of being absorbed by the body. They are considered a second-choice treatment option during pregnancy.
• Saline laxatives, such as magnesium hydroxide (Milk of Magnesia), are a type of osmotic laxative that is generally mild and safe during pregnancy, although some providers prefer to avoid magnesium-containing products.
• Stimulant laxatives, including bisacodyl (Dulcolax) and senna (Senokot, Ex-Lax), support the movement of the intestines and reduce water absorption from the large intestine. However, they should be used with caution during pregnancy due to a lack of evidence on their long-term effects.

Considerations and Recommendations

Laxatives should always be used under medical supervision, especially during pregnancy. It is crucial to consult a healthcare provider before taking any new medications, including over-the-counter (OTC) laxatives, as they can have side effects and potential interactions with other medications. Bulk-forming laxatives are generally considered the first-choice treatment option during pregnancy, as they are not well absorbed by the body and are safe to use throughout pregnancy. However, they may cause side effects such as gas, bloating, and cramping. Osmotic laxatives are a second-choice option and should be used only in the short term or occasionally to avoid dehydration and electrolyte imbalances.

Laxatives and weight loss

Laxatives are a common medicine used to treat constipation by stimulating bowel movements or loosening stool to ease its passage. However, they have also become a popular method for weight loss. Many people believe that using laxatives can help increase the frequency of bowel movements and allow for quick, easy and effortless weight loss.

How Laxatives Work

There are a few different classes of laxatives that work in different ways:

• Stimulant laxatives speed up the movement of the digestive tract.
• Osmotic-type laxatives cause the colon to retain more water, which increases bowel movement frequency.
• Bulk-forming laxatives move through the intestines undigested, absorbing water and adding bulk to the stool.
• Saline laxatives draw water into the small intestine, which helps promote a bowel movement.
• Lubricant laxatives coat the surface of the stool as well as the lining of the intestines to ease bowel movements.
• Stool softeners allow the stool to absorb more water, making it softer for easier passage.

Effectiveness of Laxatives for Weight Loss

Laxatives may help increase weight loss, but the results are only temporary. Some types of laxatives work by pulling water from your body into the intestines, allowing the stool to absorb more water for an easier passage. With this method, the only weight you lose is from the water you excrete through the stool.

There is no evidence to support the use of laxatives as a safe or effective weight loss method. One small study found that laxative use was an ineffective method for controlling body weight compared to other methods. Another study also concluded that laxatives were not effective at controlling weight, noting that laxative use was more prevalent among overweight and obese teenagers than those of a normal weight. To date, there have been no studies supporting the idea that laxative use can lead to lasting weight loss.

Side Effects of Laxatives for Weight Loss

Using laxatives for weight loss can lead to dangerous side effects, including:

• Dehydration: Laxatives make you lose water, which can cause headaches, thirst, dry mouth, and in extreme cases, heart problems, kidney failure, and even death.
• Electrolyte imbalance: Taking laxatives can result in an electrolyte imbalance, which may cause weakness and an abnormal heart rhythm. In severe cases, this can be life-threatening.
• Constipation and diarrhea: Using laxatives for longer than one week can cause loss of bowel muscle tone, leading to trouble passing stool.
• Damage: Using laxatives too often and for too long can damage your intestines and increase the chance of having colon cancer.
• Medication interference: Taking laxatives can stop your prescription medications from working properly, causing serious health problems.
• Eating disorders: People who use laxatives to lose weight are more likely to develop an eating disorder.

Safe Weight Loss Strategies

If you are considering using laxatives for weight loss, it is important to know that there are safer and more effective ways to lose weight:

• Eat more fruits and vegetables: They are low in calories but rich in fibre, which has been associated with lower body weight.
• Increase physical activity: Participating in aerobic exercise a few times a week can aid in weight loss and help prevent weight regain.
• Reduce portion sizes: Smaller portions mean fewer calories.
• Eat a high-protein breakfast: This has been shown to reduce appetite and food intake throughout the day.
• Decrease intake of added sugars: Sugar is high in calories and low in nutrients, leading to weight gain.

Frequently asked questions