The government has issued an urgent warning after a critical fault was found in a brand of adrenaline auto-injector, used during anaphylactic shock.
Patients are being warned their life-saving adrenaline injector may not work if they have been dropped and could either fail to activate, or release the dose of adrenaline too early.
Adrenaline auto-injectors are commonly given out to people with life-threatening allergies.
The warning relates to patients prescribed with an Emerade pen and only to 300 and 500 micrograms versions.
People are asked to speak to their GP immediately to obtain a prescription for, and be supplied with two auto-injectors of a different brand.
Pharmacists and pharmacy teams can also help with obtaining new prescriptions and dispensing of new pens.
The warning reads: "Patients or carers should then return all Emerade 300 and 500 micrograms auto-injectors to their local pharmacy.
"Patients should only return their Emerade pens when they have received a replacement from their pharmacy which will be an alternative brand - either EpiPen or Jext.
"They should ensure they know how to use the replacement pen, as each brand of pen works differently."
Dr Alison Cave, Medicines and Healthcare products Regulatory Agency (MHRA) Chief Safety Officer, said: "Patient safety is our top priority.
"We are taking prompt action to protect patients, following detection of damage to internal components of the Emerade pens if they are dropped, which may mean they activate too early or fail to activate and deliver adrenaline.
"The Department for Health and Social Care has confirmed that there are appropriate supplies of EpiPen or Jext adrenaline pens available for patients across the UK, however, patients will need to request a new prescription.
"Patients are reminded to carry two pens with them at all times as normal and to contact their healthcare professional when a replacement is due."
