NICE Self-harm: longer term management (CG 133)
Regarding medication issues, it recommends assessing whether the patient has access to medication and this should be removed where possible.
Using special formulations e.g. paracetamol soluble, when administering medication to inpatients could improve safety, as standard tablets may be hoarded and used to over-dose. Also, some types of drugs are more dangerous in overdose, for example, tricyclic antidepressants are more toxic than SSRIs, and this should be taken into account.
Photo by Sam Metsfan (Apartment in New York) [Copyrighted free use or Public domain], via Wikimedia Commons