Stool Softeners vs. Laxatives: A Complete Guide to OTC Products for Constipation

Constipation — typically defined as having fewer than three bowel movements per week — is a common complaint in healthcare providers’ offices. One study found that around 16% of U.S. adults experience constipation. And that number more than doubles for people ages 60 years and older. 

Changing some of your daily habits is often all that’s needed. This includes getting more physical activity, drinking more water, and eating fiber-rich foods. If these changes don’t help, there are over-the-counter (OTC) stool softeners and laxatives that treat constipation.

Here, we’ll discuss the different categories of stool softeners and laxatives, and how to decide which OTC product is best for you. 

What OTC products can I use for constipation?

OTC constipation products include stool softeners and laxatives. One product may be preferred depending on what’s causing your constipation. It’s always best to talk to your healthcare provider or pharmacist about which constipation medication is best for you.

What’s the difference between a stool softener and laxative?

We often refer to stool softeners and laxatives as different medications. But stool softeners are actually a type of laxative called emollient laxatives. Laxatives are categorized based on how they work.

Below we’ll discuss stool softeners and the other categories of laxatives — osmotic, stimulant, saline, bulk-forming, and lubricant laxatives. 

Stool softeners (emollient laxatives)

Stool softeners are used short-term to relieve occasional constipation. They help prevent straining during bowel movements.

Specific products

The most common OTC stool softener is docusate sodium. It’s also available under the brand names Colace, and DocQLace.

How do they work?

Stool softeners allow water and fat to build up in the stool, making it softer and easier to pass. This helps avoid straining during a bowel movement, which is especially important in people with heart conditions or hemorrhoids.

How long do they take to work?

You’ll usually have a bowel movement after about 12 to 72 hours upon using a stool softener. Don’t take stool softeners for more than a week at a time. If you’re still having hard stools after a week of using them, contact your healthcare provider.

Side effects

Stool softeners usually have minimal side effects. Rarely, they cause stomach cramps or a rash. The liquid forms may cause throat irritation, so it’s important to take it with water.

Laxatives

To treat constipation, most healthcare providers recommend adding fiber to your diet or trying a bulk-forming laxative. If this doesn’t work, osmotic and stimulant laxatives are often second-choice options. Other laxatives, like saline or lubricant laxatives, may be good options in certain situations. 

Bulk-forming laxatives

Specific products

Bulk-forming laxatives are available as OTC products, including: 

• Calcium polycarbophil (FiberCon)

• Psyllium (Metamucil) 

• Methylcellulose (Citrucel)

How do they work?

Bulk-forming laxatives add soluble fiber to the stool, causing more water absorption. This creates a heavier stool which encourages the colon to contract and eliminate the stool. You should drink a lot of water while taking bulk-forming laxatives. A lack of water can lead to complications with these medications, like a blockage in the intestines.

Healthcare providers will usually recommend you start with a small dose, and slowly raise it until you have regular bowel movements.

How long do they take to work?

Bulk-forming laxatives usually produce a bowel movement within 12 to 72 hours. If you’re still experiencing constipation after 7 days, contact your healthcare provider. 

Side effects

Similar to other laxatives, bulk-forming laxatives can cause gastrointestinal side effects like bloating, diarrhea, and nausea.

People who can’t get out of bed, have fluid restrictions (like in heart failure), or who have issues with cognition should avoid bulk-forming laxatives.

Osmotic laxatives

Specific products

Osmotic laxatives are available as OTC products, including: 

• Miralax Polyethylene glycol, or PEG (Miralax)

• Glycerin (Fleet and Pedia-Lax suppositories)

How do they work?

Osmotic laxatives allow water to be easily absorbed in the small intestine. This creates a softer and bulkier stool, making it easier to pass. One of the most commonly used osmotic laxatives is PEG. PEG is a first-choice option for constipation because it’s effective and usually doesn’t cause many side effects. Besides treating constipation, it’s commonly used to prepare the bowel before a colonoscopy. 

How long do they take to work?

Oral PEG usually works within 1 to 3 days. Glycerin — a rectal suppository — usually takes 15 minutes to 1 hour to work.

Side effects

Osmotic laxatives usually have minimal side effects, but the most common are stomach pain, diarrhea, and nausea. 

If you have kidney problems, talk to your healthcare provider before taking osmotic laxatives. They may monitor your electrolyte levels or recommend another laxative.

Stimulant laxatives

Specific products

Stimulant laxatives are available as OTC generic and brand name products, including Bisacodyl (Dulcolax) and Senna (Senokot, Ex-Lax).

How do they work?

Stimulant laxatives cause muscle contractions in the digestive tract. This allows the stool to move quickly through the intestines, resulting in more frequent bowel movements. Stimulant laxatives are usually recommended when osmotic laxatives don't work.

How long do they take to work?

Stimulant laxatives can produce a bowel movement in 6 to 12 hours if taken orally, and 15 minutes to 1 hour if given rectally.

Side effects

The following side effects can occur with stimulant laxatives:

• Diarrhea

• Stomach pain

• Nausea

• Vomiting

• Headache

Saline laxatives

Specific products

Saline laxatives are available as OTC products, including:

• Magnesium hydroxide (Milk of Magnesia)

• Magnesium citrate (Citroma)

• Magnesium oxide (Phillips’ Laxative Caplets)

• Saline enema (Fleet enema)

How do they work?

Saline laxatives draw water into the bowel, leading to softer stool and more frequent bowel movements. All saline laxatives are some form of a salt, which naturally draws water. Sometimes they’re categorized as an osmotic laxative because they work similarly. 

Saline laxatives work quickly and can be used to clear the colon before a colonoscopy. 

How long do they take to work?

Saline laxatives usually work within 30 minutes to 6 hours. But an enema formulation can work in just 1 to 5 minutes. Contact your healthcare provider if you don’t have a bowel movement within 30 minutes of using a saline enema. 

Side effects

Oral saline laxatives can cause loose and watery stools. The rectal enema formulation can cause: 

• Stomach pain 

• Bloating

• Nausea

• Chills

Lubricant laxatives

Mineral oil is the only OTC lubricant laxative. It’s available as a generic oral liquid or a rectal enema (Fleet Mineral Oil Enema.)

How do they work?

Mineral oil makes the surface of stools slippery, which helps them pass through the body more easily. It can be used rectally for constipation caused by impaction (a hard lump of stool that gets stuck in the rectum).

How long do they take to work?

Mineral oil usually works within 6 to 8 hours when taken by mouth, and within 15 minutes when used rectally.

Side effects

The following side effects can occur with mineral oil use:

• Stomach pain

• Strong urge to have a bowel movement

• Nausea

• Diarrhea

If mineral oil is accidentally inhaled into the lungs (aspiration), pneumonia can occur. Avoidmineral oil if you have difficulty swallowing.

Can you take stool softeners and laxatives together?

In some situations, your healthcare provider may recommend combining a stool softener and laxative. There's an OTC product that combines a stool softener (docusate) and a stimulant laxative (senna). It’s available under the brand names Senna-S, Dok Plus, or Senexon-S. It generally works within 6 to 12 hours.

You shouldn't take docusate and mineral oil together. This can cause too much absorption of the mineral oil.

Who shouldn’t take stool softeners or laxatives?

If you have kidney or heart issues, ask your healthcare provider before taking laxatives. Certain types of laxatives could make your kidney issues worse. Osmotic laxatives increase the amount of fluid in the body and could overload your heart.

Constipation is more common during pregnancy. Non-medication interventions — like increasing your fiber intake — should be tried first. Pregnant people should aim for 25g of fiber daily. If you need medication, your obstetrician may recommend bulk-forming laxatives, Milk of Magnesia, or stool softeners.

Avoid OTC laxatives and contact your provider if you have severe stomach pain, nausea, or vomiting along with constipation.

When should I call my healthcare provider?

Taking laxatives for too long can cause dehydration and electrolyte imbalances. Contact your provider if you’ve been taking laxatives for over a week with no improvement. You should also contact your provider if you vomit, have blood in your stool, or if you haven’t had a bowel movement in 3 days. 

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Written by:

Sarah Lobello Pearson, PharmD

Sarah Pearson is a practicing pharmacist with over 10 years of experience in the field. She received her doctorate in pharmacy from the University of Georgia in Athens, GA.

Edited by:

Amy B. Gragnolati, PharmD, BCPS

Amy Gragnolati, PharmD, BCPS, is a pharmacy editor for GoodRx. Amy currently holds her pharmacist license in Georgia and California.

Reviewed by:

Christina Aungst, PharmD

Christina Aungst, PharmD, is a pharmacy editor for GoodRx. She began writing for GoodRx Health in 2019, transitioning from freelance writer to editor in 2021.

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