As UK politicians prepare to vote on Prime Minister Theresa May’s Brexit deal tonight, the possible impact of leaving the European Union without a deal on the country’s healthcare is only just becoming clear. At worst, pharmacies could run out of certain drugs, and hospitals may have to delay operations, scans and other procedures.

A no-deal exit from the EU on 29 March would pose immediate problems for the supply of important drugs. About two-thirds of medicines used in the UK are imported from the EU. At the …