It has four units in Birmingham, Cardiff, Edinburgh and Newcastle. It is a member of the European Association of Poisons Centres and Clinical Toxicologists.
* NPIS Birmingham Unit (West Midlands Poisons Unit), City Hospital, Birmingham - Dr Sally Bradberry
* NPIS Cardiff Unit, Llandough Hospital - Dr Laurence Gray
* NPIS Edinburgh Unit (Scottish Poisons Information Bureau), Royal Infirmary of Edinburgh - Dr. Euan Sandilands.
* NPIS Newcastle Unit, Regional Drug and Therapeutics Centre, Newcastle University - Professor Simon Thomas
NPIS Birmingham has the NPIS Product Data Centre, provided by manufacturer's information, and deals with around 2,300 companies.
NPIS supports (24 hours) NHS Direct (for England and Wales) and (24 hours) NHS 24 for Scotland. Northern Ireland has its Northern Ireland Regional Medicines and Poisons Information Service in Belfast, and NPIS is used when this is not available. The Republic of Ireland uses the service, via the TOXBASE database, which is used by the country's National Poisons Information Centre.
Of all UK nations, Wales has the highest proportionate number of enquiries to the service, with Northern Ireland the fewest. Within England, there is a distribution of higher number of enquiries to the service in the north than the south, with NHS North East having the highest and NHS South of England having the least proportionate number of enquiries. The vast majority (95%) of enquiries come from A&E departments. Around 65% of poisoning is from pharmaceuticals (paracetamol, ibuprofen, citalopram, diazepam and zopiclone) and 15% from household chemicals (detergents, bleach, and isopropanol). There are very dangerous chemicals stored in most UK kitchens.
Wednesday is the busiest day of the week for enquiries, with the fewest at the weekend.