Key Facts

  • Constipation is typically present throughout all stages of PD.
  • Medications< used to treat PD symptoms may cause constipation.
  • Proper dietary fiber intake, changes in lifestyle, and changes in medication regimen are the best measures for managing constipation.
  • Importance of constipation includes poor absorption of medications leading to dose failures and immobility.

Clinical Best Practices

  • All patients, including those with PD, should have a colonoscopy after they reach the age of 50 and every 7 to 10 years thereafter.

Constipation is very common in PD and can precede the diagnosis by many years.

Common Causes

  • Impairment in gut motility
  • Dysfunction in muscles of the pelvic floor that promote defecation
  • Medications such as anticholinergics (trihexyphenidyl, benztropine, oxybutynin, amantadine)


Barriers to Diagnosis

  • Failure to disclose. (Ask direct question: “Do you have a BM every day?”

Treatment Options

  • Increased water intake and fiber in the diet are the first steps.
  • Exercise may also improve bowel movement frequency.
  • Bulk forming agents such a psyllium can be added to the diet.
  • Laxatives such as polyethylene glycol 3350 should be added if these measures fail.
  • If required, introduce relatively safe antiemetics including domperidone (outside the US), trimethobenzamide, and ondansetron.

Important Caveats to Therapy

  • Occasionally, moderate to advanced PD patients can become so constipated that they develop an impaction with intestinal obstruction. This requires immediate attention and evaluation/treatment, perhaps requiring hospitalization<.
  • It is important to avoid GI drugs (such as prochlorperazine, metoclopramide, and promethazine) that may worsen parkinsonism.
  • Patients often do no adhere to treatment plans due to fear of “dependence” on bowel routine and lack of understanding the impact of severe constipation (can cause bowel obstruction).