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When Do You Need a Prescription Laxative?

If You Can't Have a Bowel Movement -- Even With OTC Laxatives -- Then You Might Need to Call a Doctor

By Nancy Larson

Updated February 24, 2009

(LifeWire) - Maybe you've been using OTC laxatives for a week now and still having significant constipation, with straining and hard stools. Or perhaps you have other symptoms in addition to constipation. A doctor can determine whether you need assistance from a prescription laxative or whether your symptoms might signal a more serious medical issue.

You need to see a doctor if you have any of these symptoms, particularly when you're constipated:

  • Nausea, vomiting or stomach pain
  • Sudden alteration of bowel habits that continues for two weeks
  • Rectal bleeding
  • No bowel movement after taking a laxative
  • Need for laxatives for longer than one week

Laxatives You Might Be Prescribed:

Enulose or Generlac (lactulose): Lactulose is a synthetic sugar that breaks down in your body into substances that pull water from the body into the colon, which softens stools. It is available only as a liquid and is taken once a day. You should not take lactulose if you are on a low lactose (milk sugar) diet, are diabetic, are taking any other laxatives or antacids, or if you have upcoming surgeries, especially an intestinal procedure like a colonoscopy.

Side effects may include diarrhea, gas and upset stomach. If you experience stomach pain or cramps, discontinue using lactulose and call your doctor. It may take up to two days for lactulose to produce a bowel movement.

MiraLax (polyethylene glycol 3350): Once prescription-only, full-strength MiraLax is now available over the counter. It causes stool to retain water, which softens it, allowing easier passage. You mix it with a glass of water. MiraLax may need to be taken for two to four days to work. Side effects can include upset stomach, cramping, bloating and gas. Call your doctor if any of these signs is severe or lasting.

Amitiza (lubiprostone): By boosting the amount of fluid in the intestines, Lubiprostone softens the stool, making it easier to have a bowel movement. It's used to relieve ongoing constipation whose cause is not an illness or medication, but an unknown factor.

If you've ever had Crohn's or Hirschsprung's disease, hernia, gallstones, impacted bowel movement, diverticulitis, polyps or other blockages in your digestive system, you may not be able to take lubiprostone. Or you may need to be tested while taking it to make sure it's not harming you.

Stop taking lubiprostone and get immediate medical care if you develop serious side effects like facial, lip, tongue or throat swelling, or if you get hives, have difficulty breathing or develop severe diarrhea or vomiting.


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LifeWire, a part of The New York Times Company, provides original and syndicated online lifestyle content. Nancy Larson is a St. Louis-based freelance writer whose work has appeared in dozens of local and national print and online publications including CNN.com, The Weather Channel, Health magazine and The Advocate.

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