People carrying Emerade 500 microgram adrenaline auto-injector pens should return them and get hold of a prescription for a different brand.
A fault has been detected in the pens, meaning the dose of adrenaline may not be delivered when needed for people with severe allergies.
The official advice comes from the Medicines and Healthcare products Regulatory Agency (MHRA).
Alternative brands - EpiPen and Jext - are available up to 300 micrograms.
"Action has been taken to protect patients, following detection of a fault in one component of the Emerade adrenaline auto-injector pens," an MHRA spokesperson said.
"Patients should return all Emerade 500 microgram pens to their local pharmacy once they have a new prescription and have been supplied with pens of an alternative brand."
If an Emerade pen does need to be used before a patient can get hold an alternative pen, the advice is that it should be pressed very firmly against the thigh.
If this does not work, the patient should immediately use their second pen.
Carry two pens reminder
The MHRA said it was vital patients contacted their doctor when a replacement pen was due - and always carried two pens at all time.
They should also make sure they are familiar with how to use the pen when switching to a different brand.
The recall of the Emerade 500 microgram auto-injectors follows the previous recalls of Emerade 150 and 300 microgram auto-injectors.
The pens were recalled in three phases to ensure there would enough supplies of the alternative pens - EpiPen or Jext - for patients.
Data shows that that a single EpiPen (300 microgram) or Jext (300 microgram) pen is a suitable replacement for an Emerade 500 microgram pen, the advice says.
Patients who need to return auto-injector pens should follow advice on social distancing.
• a patient or carer should make a telephone appointment with their doctor to request a prescription for replacement pens of a different brand. Unless their doctor advises otherwise, they should not visit the GP surgery in person
• request the prescription is sent to a pharmacy to avoid collecting personally from the surgery
• if a patient and/or their household is self-isolating, ask a friend or relative to collect the replacement pens from the pharmacy. Some pharmacies offer a home delivery service
• once the patient has the replacement auto-injector pens, return Emerade 500 mcg pens to the pharmacy. Some pharmacies have drop-off boxes to facilitate distancing.