The Ynys Môn AM has called for more Welsh Government support to treat drug addiction following several deaths in the Llangefni area.
Rhun ap Iorwerth told the Senedd on Wednesday that five people had died recently as a result of misuse.
The Plaid Cymru AM said local residents have raised concerns with him about drug users mixing benzodiazepine with other substances.
Health Minister, Vaughan Gething, said he would investigate the matter further and asked Mr ap Iorwerth to contact him.
Mr ap Iorwerth said the number of recent drug-related deaths on Anglesey appeared to be a ”very worrying pattern” and the results of such misuse had been ”tragic”.
”I say that I have become aware of this because there has been no publicity regarding this matter, and what I’ve heard has come from people in our communities speaking to me to share their concerns.”
”Having made enquiries with the police and the coroner, it would appear that data isn’t collected in terms of a particular drug that might cause a death, and that it is only registered as a contributory factor.”
”I will be writing to (the) Welsh Government to ask them to look into these deaths, to investigate the possibility of a pattern existing, and appealing for extra support, which is obviously urgently needed in order to offer help to those who are addicted to drugs, so that we can prevent these tragic deaths.”
Mr Gething, quoting official figures published last year, said mortality rates for drug abuse on Anglesey was 6.4, below the national Wales average of 7.2 – representing two such deaths on the island.
He added: ”Any drug-related death is a tragedy and we increased our investment to help tackle substance misuse.”