Laxatives: What to know about choosing the right one

Occasional irregularity is a fact of life, but you can minimize constipation with some basic steps. You should be sure you are eating a fiber-rich diet, drinking adequate fluids, and staying physically active.

But when you have persistent constipation, the best laxative is the gentlest and safest option, like a bulk-forming laxative. If laxatives don't work or if you constantly need to take laxatives, you should discuss this with your doctor.

There are three main types of laxatives: bulk forming, stool softeners, and stimulant.

First choice: bulk-forming laxatives

Bulk-forming laxatives absorb liquid in the intestines and "bulk up" the stool with fiber, making it softer and encouraging contractions of the bowel. But don't expect instant gratification: these can take half a day to several days to provide relief. They are safe to use daily. They contain various ingredients, and you may have to try more than one to find the product that helps you with minimal side effects, such as flatulence and bloating. They may be marketed as laxatives or as fiber supplements. Examples of bulk-forming laxatives include Metamucil, Citrucel, and Fibercon.

Stool softeners

Stool softeners are a specific type of laxative that work by adding water and fat to stools to make them easier to pass. They come in capsule, tablet, powder, liquid, and syrup form and are usually taken at bedtime. Be sure to take a stool softener exactly as directed. Some examples include Colace and Surfak.

Lubricant laxatives

Mineral oil, a lubricant, helps stools "slide on by" if they feel stuck low in your bowels, if you have an internal tear (fissure), or if you have pain from hemorrhoids during bowel movements.

Don't take mineral oil at the same time as stool softeners. Take 1 tablespoon with breakfast or lunch. But don't use mineral oil for more than a few days, because it interferes with absorption of some vitamins. If inhaled, mineral oil can cause pneumonia. Consider wearing a protective pad in your underwear to absorb any leakage.

Osmotic laxatives

Osmotic laxatives draw water into the intestine, softening the stool and increasing bowel movements. If stool softeners aren't providing enough help, the osmotic laxative polyethylene glycol (MiraLAX or a generic version) is a good next step. Common side effects are gas, bloating, and nausea.

Another osmotic option would be a magnesium-based laxative such as milk of magnesia or magnesium citrate. The active ingredients include magnesium, sulfate, citrate, and phosphate.

Sugar alcohols are found in sugar-free candies, chocolates, and other products. These compounds - which include sorbitol, xylitol, mannitol, erythritol, and others - can act like osmotic laxatives. People's tolerance for sugar alcohols depends on many factors, including body weight and the type of sugar alcohols ingested. Sugar alcohols can cause diarrhea, bloating, cramping, and gas.

Don't take more than the recommended amounts of these laxatives, or use them long-term, because they can throw off your body chemistry. Combined with underperforming kidneys or heart failure, osmotic laxatives can be dangerous.

Stimulant laxatives

Stimulant laxatives, such as senna and bisacodyl, trigger contractions in the bowels that push the stool along. These laxatives typically work within six to 12 hours. But if you take stimulant laxatives too often, you could become dependent on them and unable to have a bowel movement without taking them - possibly because the bowel has stopped functioning normally.

When to seek medical help

If you find yourself trying one laxative after another, see your primary care provider for an evaluation. Additional testing can lead to better treatment and rule out any possible serious problems. And if it is just constipation, your provider can offer other medications that may be more helpful than over-the-counter laxatives.

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