The UK imports 37 million packs of medicine each month from the EU.
Concern has been raised that prolonged disruption at the borders in the event of a no-deal Brexit could disrupt the supply chain.
The government has asked firms to start stockpiling a six-week supply of drugs, but worries are growing that the public may need to do the same.
Martin Sawer, of the Healthcare Distributors Association, told MPs the medication industry was “very concerned” about a no-deal as it could have “catastrophic” consequences for the supply of drugs.
Mr Sawer said there was no need for the public to do the same “yet”, but the picture could change very quickly.
Appearing before the House of Commons’ Health and Social Care Committee, he said small firms in particular were struggling to stockpile drugs, as they do not have the cash flows to fund reserves of drugs.
Mr Sawer told the cross-party group of MPs: “We need politicians to understand there could be consequences.
“We are not suggesting anybody needs to stockpile outside of the supply chain yet.”
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NO DEAL BREXIT EXPLAINED: The government has asked firms to start stockpiling a six-week supply
“But come January that might be a different picture,” he added.
“We are, we believe, going to be in a difficult situation if there is not a deal by Christmas.”
The main worry here is if we don’t get a deal, there will be mammoth queues of providers bringing drugs in from the EU that will have to undergo border checks which they didn’t have to previously.
Mike Thompson, chief executive of the Association of the British Pharmaceutical Industry, said he did not want to alarm vulnerable patients.
NO DEAL BREXIT EXPLAINED: The UK imports 37 million packs of medicine each month from the EU
He insisted drug firms would do everything they could to get medications to those who need them.
But he added: “Stockpiling won’t be enough.”
Express.co.uk also to spoke to Jean V McHale, Professor of Health Care Law, University of Birmingham, on the issue.
She said: “To be fair to the government, the Department of Health has said that they are making contingency plans on this, but obviously that in itself that will involve cost.”
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She added: “If there are delays at Dover…it’s just that nobody is precisely sure how it’s going to play out.”
There is the additional, longer-term worry of Britain’s ongoing place in the medical community, and whether we’ll still be an attractive market.
If we crash out of the EU’s drug testing market, Professor McHale said there’s a chance “we wouldn’t become a primary launch market for drugs, so the UK patients might as a result get drugs later.
“It definitely might mean that drugs aren’t available as fast, so a new lifesaving treatment we might get later. We might be behind other patients.”
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NO DEAL BREXIT EXPLAINED: Worries are growing that the public may need to stockpile drugs
A Department of Health and Social Care spokesman said patients should not stockpile drugs.
He said the government was “working closely with partners” to ensure there were adequate stockpiles of medicine if there was a no-deal Brexit.
“The government is confident of reaching a deal with the EU that benefits patients, and the NHS is preparing for all situations.
“We are working closely with partners to ensure adequate stockpiles are in place for all medicines which may be affected in the event of a no-deal Brexit.
“Our number one priority is to ensure that patients have access to safe and effective medicines – and we have some of the cheapest drug prices in Europe.”