Is it permissible for a doctor to ask a patient suffering from depression and trichotillomania to shave his beard or trim it temporarily as part of the treatment, and is it permissible for the patient to do so until he recovers?

There is no harm in trimming or shaving the beard of a mentally ill patient if the doctor believes that it will contribute to their treatment. Psychiatric illnesses are classified as real diseases that lift hardship. Islamic law has permitted the sick to have hardship lifted and to be granted ease in worship as a relief for them. Allah Almighty says: "Nor is there any hardship on the sick." This is conditioned upon the doctor confirming that shaving or trimming will lead to recovery.