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Constipation drugs: Summary of Recommendations
Constipation is very common. Like headaches and colds, almost everyone will experience a bout at some point. For most, these episodes are brief and usually don't require medical treatment. But doctors start to get concerned if the frequency of your bowel movements drops below three per week for at least two weeks. At any one time, an estimated 35 to 45 million people in the U.S. are in that predicament, or have been diagnosed with chronic constipation or a condition called Irritable Bowel Syndrome (IBS).

If you are constipated, the first thing to do is eat more fiber-rich foods such as vegetables, fruits, whole gains, legumes and beans. If that doesn't work, try a fiber supplement. Our analysis found that those containing psyllium are best. If your constipation persists for two to three weeks, you may need a drug. A variety are available, both nonprescription and prescription. These include stool softeners and different types of laxatives. The vast majority of people will get the help they need from inexpensive nonprescription drugs.

Taking cost and the evidence for effectiveness and safety into account, we chose the nonprescription drug polyethylene glycol (MiraLax) as our Best Buy. This drug improves constipation symptoms and is just as effective as a prescription drug called lactulose. In addition, it has a track record of being safe and well tolerated by most people. We caution against the long-term use (beyond a few days) of the laxatives senna (Senokot, Ex-Lax) and bisacodyl (Correctol, Doxidan, Dulcolax). Studies indicate these drugs are less effective against chronic constipation.

If you're unable to tolerate MiraLax or it doesn't improve your symptoms, you should talk to your doctor about other options, which may include generic lactulose or lubiprostone (Amitiza). Warning: Amitiza is a new and expensive prescription drug which may be no more effective than MiraLax or lactulose for most people and its safety profile is not fully established.

Amitiza is also approved for women who have IBS with constipation as the main symptom (and many doctors will prescribe it for men too). But we advise people with this condition to talk to their doctors about trying other medicines first, in addition to lifestyle changes, and only consider Amitiza if these strategies fail to provide relief.

This report was released and last updated in December 2008.
Constipation drugs: drug comparison
CR Best Buy Constipation Drugs - Cost Comparison*
Generic Name, Form, and Dose Brand Name(s)1 Number of Units Per Day2 OTC or Rx?3 Cost4 Compare Prices
Longer-term Use - Monthly Cost5
  Docusate capsule 50mg Generic One-Three OTC $6-$18
  Docusate capsule 50mg Colace One-Three OTC $10-$30
  Docusate capsule 100mg Generic One-Three OTC $3-$9
  Docusate capsule 100mg Phillips One-Three OTC $6-$18
  Docusate capsule 240mg Generic One OTC $4
  Docusate capsule 240mg Kaopectate One OTC $13
  Lactulose powder 10g Kristalose Two-Three Rx $55-$82
  Lactulose powder 20g Kristalose One Rx $80
  Lactulose solution 10g Generic Two-Three Rx $40-$60
  Lactulose solution 10g Enulose, Generlac, others Two-Three Rx $40-$60
  Lubiprostone capsule 8mcg Amitiza Two Rx $220-$294
  Lubiprostone capsule 24mcg Amitiza Two Rx $190-$298
best buy Polyethylene glycol powder 17g MiraLax (OTC) One OTC $23
  Polyethylene glycol powder 17g Glycolax (Rx) or Generic One Rx $39
Short-Term Use Only - Per Episode Cost6
  Bisacodyl tablet 5mg Generic One-Three OTC $1-$2 or less
  Bisacodyl tablet 5mg Dulcolax, Ex-Lax Ultra Strength One-Three OTC $1-$2 or less
  Senna tablet 15mg Generic Two pills once or twice daily OTC $1-$2 or less
  Senna tablet 15mg Senekot, Ex-Lax Two pills once or twice daily OTC $1-$2 or less
  Senna tablet 25mg Generic Two pills once or twice daily OTC $1-$2 or less
  Senna tablet 25mg Ex-Lax Maximum Strength Two pills once or twice daily OTC $1-$2 or less
In Hospital or Special Use - Monthly Cost7
  Alvimopan capsule 12mg Entereg Two Rx $950
  Methylnaltrexone injection 12mg Relistor 8-12 mg every 2 days Rx $569-$1,037
  Tegaserod tablet 6mg8 Zelnorm Two Rx Price not available
*Selected doses are listed. Also, not all brands or branded generics (of which there are many) are included.
1. "Generic" means this row lists the price for the generic version of this medicine.

2. The drugs listed come in pill, liquid, and powdered form. Unit refers to pill or liquid or powdered dose, as typically recommended.

3. "OTC" means over-the-counter, indicating the drug on this row is available without a prescription. "Rx" means the drug on this row is available by prescription only.

4. Prices are from multiple sources. Among those sources are online pharmacies and major pharmacy chains in the Washington DC area. Prices were obtained in December 2008. Pricing information for some prescription drugs was also derived by Consumer Reports Best Buy Drugs from data provided by Wolters Kluwer Health, Pharmaceutical Audit Suite.® This data represents nationwide averages for October 2008. Wolters Kluwer Health is not involved in our analysis or recommendations. The costs of all of these medications can vary tremendously, especially online, so we encourage you to shop around to find the best price.

5. These medicines can be taken everyday for weeks or months, but also may be taken just a few times a months for occasional constipation. We give the average monthly cost here.

6. These medicines are not recommended for long-term use. We give the average price for a single bout of constipation.

7. These are specialty medicines for severe constipation. The monthly cost is given but in practice use may be for days or a few weeks only.

8. Zelnorm is now no longer readily available to most patients. It can only be obtained through a special request to the FDA.