However, under the EU deal, 15% is the maximum tariff, and isn't added to any existing rate. For Britain, the 10% base rate is in addition to the "most-favoured nation" (MFN) rates that the U.S. applies as a minimum to specific goods imports from all its trade partners, so the effective tariff rate is often higher.

The European Union's trade deal with the United States could cost the pharmaceutical industry between $13 billion and $19 billion as branded medicines become subject to a tariff of 15%, analysts said on Monday.

Business leaders on both sides of the Atlantic breathed a sigh of relief that the U.S. and European Union had averted a bruising trade war.

Despite a new EU-US trade deal, tariffs on pharmaceuticals remain uncertain and unchanged for now, pending the outcome of a US national security investigation that could later impose duties of up to 15%.