Laxatives

What are laxatives?

Laxatives are medications that are used to encourage bowel movements. There are several different types of laxatives available, such as bulk-forming laxatives, osmotic/hyperosmolar laxatives, lubricants, stool softeners, and stimulant laxatives. Laxatives are available as liquids, tablets, capsules, chewable tablets, enema solutions, and suppositories that are inserted into the rectum. Many laxatives can be purchased over-the-counter without a prescription from your doctor.

What are laxatives used to treat?

Laxatives are used to treat occasional constipation. Constipation occurs when stools are less frequent than normal, more difficult or painful to pass, and have a harder and drier consistency than normal. It is often accompanied by the presence of straining or the feeling that you have to go but can’t. In general, constipation is when you have 3 or less bowel movements in 1 week or if the time between each bowel movement is more than 3 days. This number can vary according to your regular routine. It is important for you to understand what your normal routine is, and recognize when there is a change in this pattern. You can read about constipation during pregnancy here.

How do laxatives work?

There are several different ways laxatives work depending on the type of laxative.

Bulk-forming laxatives: Bulk-forming laxatives provide fiber that is normally found in vegetables, fruits, and whole grains. Fiber is not digested, so it travels to the intestines where it absorbs liquid and swells to form bulkier, softer stools. Bulk-forming laxatives need to be taken with plenty of water. It is best to gradually increase the amount of fiber that you consume, otherwise you may experience bloating, gas, and stomach cramping. Types of bulk-forming laxatives that are available include: psyllium (Metamucil), polycarbophil (Fibercon), guar gum (Benefiber), and methylcellulose (Citrucel).

Osmotic/hyperosmolar laxatives: Osmotic/hyperosmolar laxatives increase the amount of water that enters the intestines. Greater amounts of water soften stools and make them easier to pass. These medications also increase the number of bowel movements you have by making stools flow through your intestines more quickly. It is important to drink plenty of water with these laxatives to minimize the possibility of gas and stomach cramping. Types of osmotic/hyperosmolar laxatives that are available include: magnesium hydroxide (milk of magnesia), polyethylene glycol 3350 (Miralax), lactulose (Kristalose), magnesium citrate (Citroma), sodium phosphate, and sorbitol. Magnesium hydroxide, magnesium citrate, and sodium phosphate are salt forms of osmotic/hyperosmolar laxatives, and lactulose and sorbitol are sugar forms. 

Lubricants: Lubricants are oily substances that coat the stool and trap water inside of it so that stools are softer and easier to pass. Mineral oil is a type of lubricant. When taken for a long period of time, mineral oil can decrease the absorption of certain vitamins from your intestines.

Stool softeners: Stool softeners contain an ingredient that allows fluid from the intestines to mix into the stool. This softens stools and makes them easier to pass. There is no evidence that these medications are effective for treating constipation. Docusate sodium (Colace) is the most commonly used stool softener.

Stimulant laxatives: Stimulant laxatives provide fast, effective relief of constipation. They stimulate the lining of the intestine and increase muscle contractions, which cause stools to move more quickly through the intestines. While more effective, stimulant laxatives also result in more side effects. They can cause diarrhea and cramping. Stimulant laxatives should also not be used regularly because they can make your body dependent on them by disrupting its ability to have a normal bowel movement. Types of stimulant laxatives that are available include: bisacodyl (Dulcolax or Correctol), sennosides (Ex-Lax), and senna (Senokot). 

Castor oil: Castor oil is made from castor beans. It encourages movement of stool by keeping fluid in the intestines. 

You can read more about laxative use during pregnancy and natural methods to deal with constipation here.

If I am taking a laxative, can it harm my baby?

The risks that laxatives pose to your baby will differ based on the type of laxative used. Many laxatives are poorly absorbed, so your baby is unlikely to be exposed to much of the medication when used at recommended doses. There is very little evidence for the safety of laxatives in pregnancy. You should always ask your doctor before using laxatives during pregnancy. Your doctor will determine which medication is safe and beneficial for both you and your baby. All laxatives should only be used for short periods of time and within recommended doses. Excessive doses of laxatives can cause you to experience dehydration and electrolyte disturbances, which could also harm your baby.

Bulk-forming laxatives: Bulk-forming laxatives are not absorbed. Instead, they remain in the intestines. They have not been associated with an increased risk of birth defects. Bulk-forming laxatives are the first-line laxative recommended for treating constipation during pregnancy, and they are considered safe and effective.

Osmotic/hyperosmolar laxatives: The FDA recommends that lactulose should only be used during pregnancy if medically necessary. The American College of Gastroenterology (ACG) has stated that polyethylene glycol 3350 is chemically inactive and minimally absorbed, and considers it safe for use during pregnancy. There are concerns that osmotic/hyperosmolar laxatives could cause expecting moms to develop electrolyte imbalances over time. Salt forms of osmotic/hyperosmolar laxatives (magnesium citrate, magnesium hydroxide, and sodium phosphate) are not recommended during pregnancy because they can cause your body to retain salt and water, which can affect electrolyte balance. If osmotic/hyperosmolar laxatives are used, they should only be used for short periods of time to prevent dehydration and electrolyte imbalances. 

Lubricants: Mineral oil is not recommended during pregnancy by the ACG because it may be associated with reduced absorption of some vitamins, which could lead to hemorrhage (bleeding from blood vessels) and a blood disorder in the baby that interferes with the blood’s ability to clot. There is some controversy as to whether this risk actually occurs or is only a theoretical risk.

Stool softeners: The ACG considers docusate sodium to be safe during pregnancy. However, a study determined that there is only a small amount of evidence on the use of docusate sodium in pregnancy.  The limited evidence that does exist has not associated this medication with birth defects. One report did find that using docusate sodium daily during pregnancy was associated with causing low amounts of magnesium in the blood of both the mother and baby.

Stimulant laxatives: Stimulant laxatives are considered safe in pregnancy by the ACG when used occasionally, but they are not recommended for regular use. Bisacodyl and senna are poorly absorbed, meaning that there is likely little risk to the baby. A study that looked at 1,469 expecting moms who used senna found no increased risk of birth defects.

Castor oil: Castor oil should not be used
during pregnancy because it may cause birth defects and induce premature uterine contractions. One report described an expecting mom who had taken castor oil before and during pregnancy and delivered a baby with several birth defects.  Another study also stated that castor oil may have properties that cause miscarriages. Several other reports have noted health problems that occurred in either the mother or baby after using castor oil during pregnancy.

Others: Unlike the other laxatives mentioned, there are 2 laxatives that are only available by prescription and are taken daily to treat chronic constipation with an unknown cause: lubiprostone (Amitiza) and plecanatide (Trulance). Lubiprostone has not been studied in human babies, although animal studies have suggested a possible risk of miscarriage. The FDA advises that lubiprostone should only be used in pregnancy if the benefits of treatment outweigh potential risks. Plecanatide was recently approved in 2017, so this medication has no data about use in pregnancy.

Bottom line: Mineral oil and castor oil should not be used during pregnancy. Docusate sodium may cause low levels of magnesium in the mom and baby. Other laxatives have not been associated with causing birth defects when used within recommended dosages during pregnancy. The safety data available on many of these medications is very limited. Ask your doctor before using any laxatives during pregnancy. You should contact your doctor if you are using a laxative and start having watery stools because it could lead to dehydration.

If I am taking a laxative and become pregnant, what should I do?

If you become pregnant while taking a laxative, contact your doctor immediately. Your doctor will decide if your medication should be discontinued or if a safer alternative should be provided.

If I am taking a laxative, can I safely breastfeed my baby?

Always ask your doctor before using any laxatives while breastfeeding. There is very little data available on the safety of these medications in the breastfed baby, but there have been a few reports of loose stools in babies exposed to certain laxatives through breast milk.

Bulk-forming laxatives: Psyllium is considered acceptable while breastfeeding. One study looked at 11 nursing moms who were given a laxative that contained psyllium and sennosides. None of the babies had any loose stools.

Osmotic/hyperosmolar laxatives: A study that looked at nursing moms who took milk of magnesia or mineral oil found no changes in stool frequency or consistency in breastfed babies. Taking either magnesium hydroxide (milk of magnesia) or magnesium citrate while nursing is not expected to affect the amount of magnesium in the baby. 

Lubricants: The study mentioned above did not find loose or more frequent stools in breastfed babies exposed to mineral oil through breast milk. The oral use of mineral oil is considered acceptable while breastfeeding, but repeated use should be avoided due to the risk of deficiencies in certain vitamins. Due to its poor absorption when taken orally, it is likely that little or no mineral oil will reach the breastfed baby or cause side effects.

Stimulant laxatives: The study mentioned above in bulk-forming laxatives did not find loose or more frequent stools in babies exposed to a laxative containing psyllium and sennosides. Some reports have found that senna caused loose stools in breastfed infants, but others did not notice this side effect. The American Academy of Pediatrics has indicated that senna is usually compatible with breastfeeding. Bisacodyl is not absorbed from the intestines and is considered acceptable while breastfeeding.

Castor oil: There have not been any reports of breastfed babies exposed to castor oil. Due to the lack of information, other laxatives may be preferred in nursing moms.

Others: It is unknown whether lubiprostone or plecanatide pass into milk, but they have the potential to cause serious side effects in the breastfed baby. Your doctor will determine whether nursing should be discontinued or if the medication should instead be discontinued while breastfeeding.

Bottom line: Ask your doctor before using any laxatives while breastfeeding. There have been a few reports of loose stools with the use of senna in breastfed babies. If you use a laxative, contact your doctor if you notice that your baby starts having loose stools.

If I am taking a laxative, will it be more difficult to get pregnant?

Using laxatives according to recommended dosages will likely not affect fertility.

If I am taking a laxative, what should I know?

Always ask your doctor before taking or continuing laxatives during pregnancy or breastfeeding. There is very little evidence on the safety of these medications in pregnancy and lactation. Some laxatives, such as mineral oil and castor oil, should not be used in pregnancy. Docusate sodium use during pregnancy has been associated with causing low amounts of magnesium in the mom and baby. If you require laxatives, your doctor will help you determine which medication is safest for both you and your baby.

If I am taking any medication, what should I know?

This report provides a summary of available information about the use of laxatives during pregnancy and breastfeeding. Content is from the product label unless otherwise indicated.

You may find Pregistry's expert reports about digestive disorders here and about the individual medications used for digestive disorders here. Additional information can also be found in the resources below. 

Resources for laxatives during pregnancy and breastfeeding:

For more information about laxatives during and after pregnancy, contact http://www.womenshealth.gov/ (800-994-9662 [TDD: 888-220-5446]) or check the following links:

• Patient: Laxatives
• The American Gastroenterological Association. Understanding Constipation
• WebMD: Safely Using Laxatives for Constipation.
• American College of Gastroenterology: Pregnancy in Gastrointestinal Disorders.