Laxative Use: Monitoring Key Vitals And Labs

Laxatives are a common treatment for constipation, but they can also cause diarrhoea. There are four main types of laxatives: bulk-forming, stimulant, osmotic, and stool softeners. Stimulant laxatives are the most common and can be detected in urine samples. Therefore, when on laxatives, it is important to monitor urine samples to prevent laxative abuse and potential disorders.

Urine analysis for laxative abuse

Laxatives are commonly used to treat constipation, but laxative-induced diarrhoea is a recognised clinical condition that may need to be ruled out before other gastrointestinal investigations are carried out. There are four main types of laxatives: bulk-forming, stimulant, osmotic, and faecal softeners.

Urine analysis can be used to detect laxative abuse. Stimulant laxatives, which are the most common form, can be detected in urine using GCMS methodology. This includes the stimulant laxatives bisacodyl, danthron, rhein, and phenolphthalein. Urine samples should be collected on two or three consecutive days during a period of diarrhoea. The samples are sent to a laboratory for analysis, with results expected within two weeks.

A simple method for analysing stimulant laxatives and their metabolites in urine involves using a standardised isocratic HPLC system with diode array detection ('STIP'), which is commonly used in the Netherlands for toxicological screening. This method has been validated through ingestion of a normal dose of laxatives by human volunteers, with the expected laxative metabolite detected in urine twelve hours after intake. Urine samples from patients suspected of laxative abuse were also analysed using this method.

Another method for detecting laxative abuse in urine analysis is based on high-performance thin-layer chromatography in two systems after pretreatment of a 20-mL urine sample with beta-glucuronidase and subsequent column extraction. This method is very sensitive and can detect stimulant laxatives such as bisacodyl, danthron, phenolphthalein, and sennoside in the urine at least 32 hours after a single dose. Bisoxatin and oxyphenisatin can be detected in the urine 18 hours after intake. This procedure is highly specific and can be useful for the early diagnosis of laxative abuse.

Laxative-induced diarrhoea

Laxatives are a common treatment for constipation, but they can sometimes cause diarrhoea. This is a well-recognised clinical phenomenon that should be ruled out before other costly or invasive gastrointestinal investigations are carried out.

There are four main types of laxatives: bulk-forming, stimulant, osmotic, and stool softeners. Stimulant laxatives are the ones most likely to cause diarrhoea, as they directly stimulate the nerves and muscles of the intestines, leading to an influx of fluid and electrolytes into the intestinal lumen. Bulk-forming laxatives, on the other hand, are considered the gentlest and are least likely to cause diarrhoea. They work by adding soluble fibre to the stool, which draws water into the colon and makes the stool softer and easier to pass.

The risk of laxative-induced diarrhoea is one of the reasons why laxatives should only be used as directed and for short periods. Taking stimulant laxatives for too long can lead to a loss of muscle tone in the colon, which can worsen constipation. Therefore, it is important to consult a healthcare professional before taking laxatives, especially if you are pregnant, giving laxatives to a child, or taking prescription medication for another condition.

If you are experiencing diarrhoea after taking laxatives, it is important to stay hydrated, as diarrhoea can lead to dehydration. You should also contact your healthcare provider, especially if the diarrhoea persists or is severe. They may recommend stopping the laxatives or switching to a different type, such as bulk-forming laxatives, which are less likely to cause diarrhoea.

Types of laxatives

There are four main types of laxatives: bulk-forming, stimulant, osmotic, and faecal softeners. They are widely used to treat constipation but can also induce diarrhoea. Laxatives are available over the counter and on prescription.

Bulk-forming laxatives increase the weight of stool, which stimulates the bowel. They are considered the gentlest type and are the least likely to cause side effects. They include psyllium (Metamucil), polycarbophil (FiberCon), and methylcellulose (Citrucel). They usually take two to three days to work.

Osmotic laxatives draw water from the body into the bowel, softening the stool and making it easier to pass. They include polyethylene glycol (Gavilax, MiraLAX) and magnesium hydroxide solution (Dulcolax, Ex-Lax, Phillips' Milk of Magnesia). Osmotic laxatives also take two to three days to work.

Poo-softener laxatives, also called emollient laxatives, increase the water and fat absorbed by the stool, softening it. An example is docusate (Colace).

Stimulant laxatives activate the nerves controlling the muscles in the colon, forcing the bowel to move the stool along. They include bisacodyl (Dulcolax) and senna (Fletcher's Laxative). They are recommended if other over-the-counter types have not helped.

Laxatives come in different forms, including pills, powders, liquids or syrups, suppositories, and enemas. They should be taken as directed to prevent side effects such as bloating, gas, or stomach cramps. It is important not to take more than the recommended dose, as this can be harmful and cause side effects such as dehydration, chronic constipation, and intestinal blockage.

Laxative side effects

Laxatives are generally safe to use, but they can cause some side effects, especially if overused or misused. It is important to follow the instructions on the medicine to prevent side effects and reduce the risk of complications. Some common and less severe side effects include:

• Bloating and passing gas
• Dehydration and electrolyte imbalance (which may manifest as weakness and darker-than-normal urine)

More serious complications may require medical attention and include:

• Chronic constipation
• Intestinal blockage
• Delayed diagnosis of an underlying condition causing constipation

It is important to note that overuse of stimulant laxatives can lead to a loss of muscle tone in the colon, which may worsen constipation. Therefore, it is essential to use laxatives as directed and not to exceed the recommended dosage. If laxatives are not providing relief or are causing unpleasant side effects, it is recommended to consult a healthcare provider.

Laxative overdose

A laxative overdose occurs when someone takes more than the normal or recommended amount of this medicine, which is typically used to relieve constipation and induce bowel movements. This can be accidental or intentional. Most laxative overdoses in children are accidental, but some people, especially those with eating disorders, may take an overdose to try to lose weight.

The most common symptoms of a laxative overdose include nausea, vomiting, abdominal cramping, and diarrhea. Dehydration and electrolyte imbalances are more common in children than adults. Other symptoms may be specific to the type of laxative ingested. For example, products containing magnesium can cause a drop in blood pressure, gastrointestinal irritation, and painful bowel movements. Castor oil can also irritate the gastrointestinal tract, while mineral oil can cause aspiration pneumonia if stomach contents are inhaled into the lungs.

If you suspect a laxative overdose, do not induce vomiting unless instructed to do so by a healthcare professional. Instead, call your local emergency number or poison control center immediately. Have the following information ready: the person's age, weight, and condition; the name, ingredients, strength, and amount of the product ingested; and the time it was swallowed.

At the hospital, the patient's vital signs will be monitored, including temperature, pulse, breathing rate, heart function, and blood pressure. Treatment may include blood and urine tests, breathing support, ECG, intravenous fluids, and medications to address specific symptoms. The outcome depends on the type of laxative, the amount ingested, and the time elapsed before treatment.

Frequently asked questions