Can I Apply Ichthammol Ointment To An Itchy Anus While Having A Prolapse?

Can I apply itchammol ointment to my mom s itchy anus. She had bladder cancer. Has a prolapse. Has donut ring in to support. Recently developed a terrible itch around anus. Used ointments. Vaseline too. Nothing helped. Also used a deworming tablet. No relief yet.