Comments Patients taking weak or strong opioids almost always develop constipation.
Analgesics containing codeine in small doses are equally capable of causing severe constipation.
It is imperative that prophylactic laxatives are prescribed. Anticholinergic drugs cause constipation by a direct action on the gut wall, slowing down peristalsis. The need to treat constipation is usually the consequence of a failure in prophylaxis. The obvious most serious cause of constipation may be mechanical obstruction due to tumour. W M O'Neill, Consultant in Palliative Medicine Biochemical abnormalities such as hypercalcaemia and hypokalaemia cause constipation.