US President Donald Trump has said his administration will impose a 100% tariff on imports of branded or patented pharmaceutical products from October 1, marking a sharp escalation in his ongoing trade war.

The announcement was made in a Truth Social post on Thursday, where Trump added that exemptions would be granted to companies building new manufacturing sites in the United States. These exemptions would apply where projects were either “breaking ground” or already “under construction.” Generic medicines will not be affected by the new tariffs.

The move comes after Washington earlier this year launched a national security probe into pharmaceutical products, though it is unclear whether the duties Trump announced are directly linked to that investigation. Pharmaceuticals had previously been exempt from reciprocal tariffs introduced in April when Trump began rolling out his trade war measures.

Markets reacted quickly. Shares of Asian pharmaceutical companies fell on Friday, with Japan’s Sumitomo Pharma down 5%, Otsuka Holdings losing 4.1%, and Roche-controlled Chugai Pharmaceutical dropping 2.8%.

Trump’s posts also extended tariffs to other industries. Heavy trucks made overseas will face a 25% levy, while imported cabinets, bathroom vanities and associated products will be taxed at 50%. Upholstered furniture will be subject to a 30% tariff.

The president framed the new measures as matters of national security, saying US truckers “must be financially healthy and strong” and accusing foreign countries of “flooding” the US market with furniture products.

The pharmaceutical tariffs risk complicating existing trade arrangements. Japan’s chief negotiator has argued that the US previously granted Japan most-favoured nation status for drugs and semiconductors, ensuring duties no higher than those applied to others. The EU has also said it was assured that US levies on pharmaceutical products would not exceed 15%. Trump’s announcement raises questions about how these commitments will now be applied.