Guide to Over-the-Counter Laxatives

Many laxatives are available as over-the-counter (OTC) medications, and people often misuse them. Most people who use laxatives don’t need them, and long-term use of laxatives can have serious health repercussions like disruption of metabolite levels (body salts), dehydration, kidney injury, and even death.

How to Relieve Constipation

Instead of buying an over-the-counter laxative to help with intermittent constipation, you should first try a high-fiber diet, increased fluid intake, and regular exercise, as well as practice proper bathroom hygiene.

More specifically, you should use the bathroom when you feel the urge and refrain from “holding it in.” If these measures fail to work, you should meet with a physician to discuss laxative use, especially if you plan to take laxatives for more than a day or two.

Laxative Types

Over-the-counter laxatives are classified according to four main principal mechanisms of action:

• Bulk-forming
• Stool softeners
• Osmotic effects
• Stimulant effects

Of note, some of these laxatives work by some combination of these mechanisms.

Bulk-Forming Laxatives

As their name indicates, bulk-forming laxatives work by bulking up your stool. These laxatives are made of indigestible particles (colloid) which absorb water. Once bulk laxatives absorb water, they cause distension of the bowel and trigger bowel movement via wave-like muscle contractions (peristalsis).

Bulk laxatives are commonly made of plant fibers like methyl cellulose. When the bacteria that live in your gut digest these plant fibers, some gas (flatus) and bloating can result.

Over-the-counter bulk laxative brands include:

• FiberCon (polycarbophil)
• Citrucel (methylcellulose)
• Metamucil (psyllium)
• Konsyl (psyllium)
• Benefiber (wheat dextrin)

Stool Softeners

Stool softeners or stool surfactant agents work by permitting water and fat to suffuse your stool and thus soften it. Stool softeners can be taken by mouth or rectally (via suppositories or enemas).

Over-the-counter stool softeners include:

• Colace (docusate)
• Surfak (docusate)
• Phillips’ Stool Softener Liquid Gels (docusate)
• Mineral oil
• Pedia-Lax (glycerin suppository)

Of note, mineral oil is commonly used to lubricate stool in children and adults with a debilitating disability. In order to be palatable, mineral oil needs to be mixed with juice.

Additionally, docusate and glycerin suppositories are commonly prescribed in an inpatient or hospital setting to prevent constipation.

Stimulant Laxatives

It is not fully understood exactly how stimulant laxatives or cathartics work. We know that they directly stimulate the intestinal nervous system, as well as cause electrolyte and fluid secretion by the colon.

For some time, physicians have worried that long-term use of stimulant laxatives could lead to patient dependence on these medications. Furthermore, physicians have worried that these laxatives could damage the nervous system of the intestines (myenteric plexus).

It's still unclear whether long-term use of stimulant laxatives is safe, as more research is needed. Nevertheless, the only people who should be taking these laxatives for long periods of time are hospitalized patients or patients in long-term care facilities who have a neurological impairment and cannot leave bed.

Examples of OTC stimulant laxatives include:

• Dulcolax (bisacodyl)
• Fleet (bisacodyl)
• Senokot (senna)
• Cascara
• Ex-lax (sennosides)
• Castor oil
• Aloe

Osmotic Laxatives

Osmotic laxatives are non-absorbable compounds and soluble compounds that draw fecal water into the colon via osmosis. In this way, osmotic laxatives liquefy your stool.

Osmotic laxatives are considered effective but if overused may cause problems with your body’s water and electrolyte balance.

Here are some examples of OTC osmotic laxatives:

• Milk of magnesia (magnesium hydroxide)
• Sorbitol
• Miralax (polyethylene glycol 3350)

Sodium Phosphate Osmotic Laxatives

Phosphate laxatives are absorbed by the small intestine and have an osmotic effect to soften stool, making it easier to pass. A high dose must be ingested to produce an osmotic laxative effect.

In January 2014, the Food and Drug Administration (FDA) released a safety warning about over-the-counter sodium phosphate osmotic laxatives. They warned that in rare instances, taking more than one dose in 24 hours could cause serious harm to the kidneys and heart, and even death.

According to the FDA, "Severe dehydration and electrolyte abnormalities associated with serious complications such as acute kidney injury, arrhythmias, and death have occurred in adults and children who overdosed using oral or rectal over-the-counter (OTC) sodium phosphate solutions to treat constipation."

The FDA suggests you speak to your healthcare provider before taking this type of laxative and watch for warning signs of a bad reaction. 

A Word From Verywell

One of the worst things you can do with laxatives is to use them as long-term self-treatment for some more serious medical conditions and thus mask a problem that needs immediate attention. For example, colon cancer can cause constipation by way of obstruction.

Please keep in mind that—as with all medications—it’s better to prevent a problem in the first place than it is to take medications to treat it.

If you experience constipation, it’s a good idea to meet with your physician and discuss diet, fluids, exercise, and toileting habits. Lifestyle changes can often help relieve constipation and obviate the need for laxatives.