MSD Manual

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Agents Used to Prevent or Treat Constipation

Agents Used to Prevent or Treat Constipation


Some Side Effects


Bulking agents (fiber)*


Bloating, passing of gas (flatulence), and poor absorption of iron and calcium

Bulking agents generally are used to prevent or control chronic constipation.


Bloating and flatulence


Less bloating than with other fiber agents


Bloating and flatulence

Stool softeners


Stool softeners may be used to treat constipation and are often used to help prevent it.

Docusate is not effective for severe constipation.


Rectal irritation

Mineral oil

Lung inflammation caused by fats in the lungs (lipid pneumonia), poor absorption of fat-soluble vitamins, dehydration, and loss of control over bowel movements (fecal incontinence)

Osmotic agents


Abdominal cramps and flatulence

Osmotic agents are better for treating constipation than for preventing it.

Magnesium salts (magnesium hydroxide and magnesium citrate)

Too much magnesium in the body (magnesium toxicity), dehydration, abdominal cramps, and fecal incontinence

Polyethylene glycol

Fecal incontinence (related to dosage)

Sodium phosphate

Rare cases of sudden kidney failure


Abdominal cramps and flatulence

Stimulant laxatives

Anthraquinones (found in senna, cascara, and castor oil)

Abdominal cramps and dehydration

Stimulant laxatives are not used if there is a possibility of an intestinal obstruction.

Prolonged use can damage the large intestine.

Lubiprostone can be used for chronic constipation. It is available for long-term use.


Fecal incontinence, a low level of potassium in the blood (hypokalemia), abdominal cramps, and rectal burning with daily use of the suppository form


Abdominal cramps, flatulence

Not used in children


Nausea, particularly when the drug is taken on an empty stomach


Mineral oil or olive oil retention

Fecal incontinence

Although rare, giving an enema can injure the rectum if the procedure is done roughly.

Tap water

Fluid overload if a lot of water is absorbed


A high level of phosphate in the blood (hyperphosphatemia)



*The dose of fiber supplements should be gradually increased over several weeks to the recommended dose.

Lubiprostone and linaclotide are available only by prescription.