Pharmacies say a lack of government planning is behind a shortage of cough and cold medicines in shops.
The Association of Independent Multiple Pharmacies said its members report a scarcity of "all medicines", in particular cough mixtures and lozenges.
Flu and Covid cases have put pressure on the NHS and pharmacies said there should have been "better" communication with manufacturers.
Ministers said availability issues were "temporary and localised".
"We are engaging with suppliers to investigate and help ensure that over-the-counter cold and flu medicines remain available," a Department of Health spokesperson added.
Meanwhile, medicine manufacturers say there are no production issues.
But Leyla Hannbeck, chief executive of the AIMP, said there were wider logistical challenges and high demand for medicines to treat cold and flu symptoms this winter has meant the supply chain has not been able to keep up with demand.
Department of Health officials should have recognised "there are problems and communicate better" with suppliers and manufacturers, she added,
"For example, with cold and flu, we knew some months ago cases were going up... So you would have thought that plans would have been in place in terms of managing this with regards to liaising with manufacturers and getting the products in."
Ms Hannbeck told the BBC: "We have never seen this level of shortage of medicine before."
She said she did not want to create panic and urged people not to stockpile supplies, but said it was important to "raise these concerns".
"As pharmacists, we do everything we can to ensure we support patients in every way possible and try and sort alternatives, or give advice on how to manage cold and flu symptoms," she said.
About one in eight hospital beds in England are now occupied by patients with Covid and flu.
Health Secretary Steve Barclay has said such patients are putting "massive pressure" on services and the NHS was facing huge challenges. He said the government was providing extra funding to help.
The trade association representing the manufactures of over-the-counter medicines said companies were running at "maximum capacity" to meet demand and "not reporting any issues supplying" their products.
Michelle Riddalls, chief executive of the Proprietary Association of Great Britain, said: "While some cough or cold products may be less readily available at some stores this is likely to be very sporadic and there are no reports of widespread shortages."
She said urged customers who cannot find their preferred brand to try alternative products or to speak to pharmacists.
High Street pharmacists Boots and Superdrug also said patients who were unable to find their preferred products should speak with their staff.
Superdrug said it had seen a huge demand for cough and cold medicines.
A spokesperson for Boots said: "General availability of cough and cold relief at our stores across the UK is good, and enough to meet current demand.
"There may be temporary shortages in some stores of a particular brand, eg Lemsip, but there will almost always be suitable alternatives available."
Flu and Covid cases have put pressure on the NHS and pharmacies said there should have been "better" communication with manufacturers.
Ministers said availability issues were "temporary and localised".
"We are engaging with suppliers to investigate and help ensure that over-the-counter cold and flu medicines remain available," a Department of Health spokesperson added.
Meanwhile, medicine manufacturers say there are no production issues.
But Leyla Hannbeck, chief executive of the AIMP, said there were wider logistical challenges and high demand for medicines to treat cold and flu symptoms this winter has meant the supply chain has not been able to keep up with demand.
Department of Health officials should have recognised "there are problems and communicate better" with suppliers and manufacturers, she added,
"For example, with cold and flu, we knew some months ago cases were going up... So you would have thought that plans would have been in place in terms of managing this with regards to liaising with manufacturers and getting the products in."
Ms Hannbeck told the BBC: "We have never seen this level of shortage of medicine before."
She said she did not want to create panic and urged people not to stockpile supplies, but said it was important to "raise these concerns".
"As pharmacists, we do everything we can to ensure we support patients in every way possible and try and sort alternatives, or give advice on how to manage cold and flu symptoms," she said.
About one in eight hospital beds in England are now occupied by patients with Covid and flu.
Health Secretary Steve Barclay has said such patients are putting "massive pressure" on services and the NHS was facing huge challenges. He said the government was providing extra funding to help.
The trade association representing the manufactures of over-the-counter medicines said companies were running at "maximum capacity" to meet demand and "not reporting any issues supplying" their products.
Michelle Riddalls, chief executive of the Proprietary Association of Great Britain, said: "While some cough or cold products may be less readily available at some stores this is likely to be very sporadic and there are no reports of widespread shortages."
She said urged customers who cannot find their preferred brand to try alternative products or to speak to pharmacists.
High Street pharmacists Boots and Superdrug also said patients who were unable to find their preferred products should speak with their staff.
Superdrug said it had seen a huge demand for cough and cold medicines.
A spokesperson for Boots said: "General availability of cough and cold relief at our stores across the UK is good, and enough to meet current demand.
"There may be temporary shortages in some stores of a particular brand, eg Lemsip, but there will almost always be suitable alternatives available."