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Laxatives: OTC Products for Constipation

Last Updated August 2022 | This article was created by familydoctor.org editorial staff and reviewed by Deepak S. Patel, MD, FAAFP, FACSM

Constipation is a common condition that makes it difficult to have a bowel movement. It can be caused by:

  • Your diet
  • Certain medicines
  • Dehydration
  • Too little physical activity
  • Intestinal problems

Constipation can usually be treated with medicines called laxatives. Many laxatives are available over-the-counter (OTC). This means you can buy them at the store without a prescription from your doctor. Some may be called stool softeners or fiber supplements.

Path to improved health

How do laxatives work?

There are several different kinds of laxatives. Each one works a different way. These are the most common types.

Bulk-forming laxatives

These laxatives add “soluble” fiber to the stool. This causes the stool to absorb more water. It creates larger, softer stools. The larger stools help trigger the bowel (intestines) to contract. This moves the stools out. Bulk-forming laxatives generally are the safest type of laxative.

Examples of bulk-forming laxatives include:

  • Psyllium (1 brand name: Metamucil)
  • Polycarbophil (1 brand name: FiberCon)
  • Methylcellulose (1 brand name: Citrucel)

To reduce your risk of side effects, you should start slowly. Make sure to drink plenty of fluids while taking bulk-forming laxatives. Gradually increase how much you use until you get the results you want.

Lubricant laxatives

These coat the surface of the stools to make them slippery. Doing this helps the stools move out of the body more easily. Glycerin suppositories lubricate the inside of the anus (the outside opening of the intestine). This makes it easier to pass hard stools out of the body.

Stool softeners

These help mix fluid into stools to soften them. This makes stools easier to pass out of the body. An example of a stool softener is docusate (1 brand name: Colace).

Osmotic laxatives

These cause the intestine to hold more fluid. This softens stools and helps the bowel move them out. Examples include polyethylene glycol (1 brand name: Miralax) and magnesium hydroxide solution (brand name: Milk of Magnesia).

Stimulant laxatives

These are the harshest type of laxatives. They cause the bowel to squeeze or contract to move the stools out. Bisacodyl (1 brand name: Dulcolax) and sennosides (1 brand name: Senokot) are examples of stimulant laxatives. Stimulant laxatives should not be used for more than a few days. When these laxatives are taken for a long time, the bowel can lose its muscle tone. It can “forget” how to push the stool out on its own. 

Should I use a laxative to treat constipation?

Most of the time, constipation doesn’t require treatment with laxatives. It will usually go away on its own. Or you can make changes in your diet and other habits. You can prevent or treat constipation by:

  • Eating foods rich in soluble and insoluble fiber (bran, oats, foods made with whole grains, fruits, and vegetables)
  • Drinking enough fluids (especially water)
  • Getting enough exercise

You may try all of these things and still be constipated. That is when taking a laxative may help you. 

How do I safely take OTC laxatives?

Before you take an OTC laxative, read the directions on the drug facts label. This will tell you how much medicine to take and how often to take it. If you have any questions about how much medicine to take, call your family doctor or pharmacist. Keep a record of the OTC medicines you are using and when you take them. If you need to go to the doctor, take this list with you.

Follow these tips to make sure you are taking the right amount of an OTC laxative:

  • Take only the amount recommended on the medicine’s label. Don’t assume that more medicine will work better or quicker. Taking more than the recommended amount can be dangerous.
  • If you are taking a prescription medicine, ask your doctor if it’s okay to also take an OTC laxative.

How can I safely store OTC laxatives?

Store all medicines out of reach and sight of young children. Keep medicines in a cool, dry place. This will help prevent them from becoming less effective before their expiration dates. Do not store medicines in bathrooms or bathroom cabinets. They are often hot and humid.

Things to consider

Most laxatives don’t have side effects if you use them correctly. However, sometimes they can cause cramping, gas, bloating, nausea, or diarrhea.

Laxatives aren’t meant for long-term use. Don’t use laxatives for longer than 1 week unless your doctor recommends it. Long-term use or overuse of laxatives can cause health problems. Overusing laxatives may also hide symptoms your doctor should know about. This could delay finding out about other health problems and starting treatment.

Some people are at risk for electrolyte imbalances while taking certain laxatives. They include children and people who have diabetes or kidney disease. Electrolytes are substances in your body. They help your nerves, organs, and muscles work properly.

Taking laxatives can cause you to eliminate too many electrolytes. When this happens, you may have side effects. These could include nausea, vomiting, headache, confusion, fatigue, and muscle weakness or spasms. Electrolyte imbalance can be serious. Check with your child’s doctor before giving him or her a laxative. If you have a chronic condition, be sure to talk to your doctor before taking a laxative.

Who shouldn’t take laxatives?

Don’t take laxatives if you are allergic to any of the ingredients. Some people may be allergic to psyllium, a key ingredient in 1 type of bulk-forming laxative.

If you have a condition called phenylketonuria, you shouldn’t take a laxative that contains phenylalanine.

Could laxatives cause problems with any medicines or supplements I take?

Laxatives can get in the way of how your body absorbs certain medicines and nutrients. Don’t take any other medicines within 2 hours of taking a laxative. If you’re taking a prescription medicine of any kind, talk to your doctor before taking a laxative. You also shouldn’t mix different types of laxatives. This includes oral laxatives (taken by mouth) and suppositories. Don’t take bisacodyl within 1 hour of taking antacids or drinking milk.

Mineral oil and castor oil are sometimes used as laxatives. They shouldn’t be used often. If mineral oil is used often, it can cause deficiencies of vitamins A, D, E, and K. Castor oil is a stimulant laxative. Using it a lot can cause you to lose muscle tone in your bowel. This can lead to long-term constipation. Mineral oil and castor oil also interact with some medicines. These include blood-thinners, antibiotics such as tetracycline, and certain heart and bone medicines.

When should I call my doctor?

If you have any of the following symptoms, talk to your doctor before using an OTC laxative:

  • Nausea
  • Stomach pain
  • Sudden change in your bowel habits that lasts 2 weeks or longer
  • Vomiting
  • Blood in stool
  • Black or dark-colored stool

Stop taking laxatives and call your doctor if you have any bleeding from your rectum. Also call your doctor if you don’t have a bowel movement after using a laxative. These could be signs of a more serious problem.

Questions to ask your doctor

  • What kind of laxative is best for me?
  • Am I taking any other medicines that will interact with a laxative?
  • Do I need a prescription laxative, or can I buy one over the counter?
  • How long should I take a laxative?
  • Can I use a bulk-forming laxative every day?
  • Are there any tests you recommend before I begin taking laxatives?


National Institutes of Health, MedlinePlus: Constipation

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