Author: Dr Ian Coulson, Consultant Dermatologist and Editor-in-Chief, 2023.
Edited by the DermNet content department
This elderly man is undergoing terminal care – he is receiving opiates for pain relief. He has developed constipation and overflow incontinence. In the last few days, he has developed this florid rash on his posterior thighs.
He has streaked erythema where there has been accidental skin exposure to his faeces.
Sadly, his opiates have constipated him, and this has been treated with co-danthrusate (dantron and docusate), an anthralin-like agent that acts as a stimulant laxative.
It is metabolised in the gut to anthralin, and when there is accidental contact with faeces and the skin, it produces an irritant dermatitis. It may oxidise to a purple-brown colour just as anthralin (dithranol) does in the treatment of psoriasis.
The co-danthrusate should be stopped and substituted with a different aperient; the erythema can be treated with a short course of a potent topical steroid.
