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Covid-19 Primary Care Resources

Covid vaccines and pre-existing allergies

GP Covid extended

Guidance on the use of Pfizer/BioNTech, AstraZeneca and Moderna Covid-19 vaccines in people with pre-existing allergies

This information is sourced from the PHE Green Book, the NHS Specialist Pharmacy Service and the MHRA:

Key Points

  • There are very few individuals who cannot receive the Pfizer/BioNtech, AstraZeneca or Moderna vaccines.
  • The vaccine should NOT be administered to those with a previous immediate-onset anaphylaxis to a previous dose of the same vaccine or any excipient of the same vaccine.
  • The Pfizer/BioNTech and Moderna vaccines should NOT be administered to those with a known PEG (polyethylene glycol or macrogols) allergy as this is one of the excipients.
  • Medicines containing PEG include some tablets, laxatives, depot steroid injections and some bowel preparations for colonoscopy. PEG allergy is rare.
  • Those with food, insect bite or latex allergies, or allergies to a single known medication can receive the vaccine.
  • Rates of anaphylaxis after the AstraZeneca vaccine are in line with the expected rate of anaphylaxis to non-Covid vaccines. The AstraZeneca vaccine does not contain PEG but does contain the related compound polysorbate 80. Polysorbate 80 is present in many medicines including the flu vaccines for over-65s. Individuals who have tolerated these vaccines (Fluad and Fluarix) are likely to tolerate the AstraZeneca vaccine. 

Observation requirements

The AstraZeneca vaccine has no requirement for observation post administration.

Product characteristics of Pfizer/BioNTech and Moderna vaccines recommend all recipients are kept under observation for 15 minutes. However, the UK Chief Medical Officers suspended this recommendation in response to the emergence of the Omicron variant. 

Vaccinated individuals should be informed how to access immediate healthcare in the event of displaying any symptoms. 

Patients should be advised not to drive for 15 minutes following any Covid-19 vaccination due to the risk of fainting. 

Management of patients with a history of allergy



Previous allergic reaction/anaphylaxis to a food, insect sting and most medicines where the trigger has been identified

Previous non-systemic reaction to a vaccine

Hypersensitivity to NSAIDs



Proceed with vaccination in any setting

Consider observation for 15 minutes



Prior non-anaphylaxis allergic reaction to Covid-19 vaccine

History of immediate anaphylaxis to multiple, different drug classes, with the trigger unidentified (this may indicate PEG allergy)

History of anaphylaxis to a vaccine, injected antibody preparation or a medicine likely to contain PEG (eg, depot steroid injection, laxative)

History of idiopathic anaphylaxis


Special Precautions

Consider possible PEG allergy. Seek allergy advice

Consider observation for 30 minutes

Some patients may benefit from pretreatment with antihistamine. However, this may mask initial symptoms



Prior anaphylaxis reaction to Covid-19 vaccine

Prior systemic allergic reaction to a component of the vaccine (for known PEG allergy – see text above)


Vaccination Contraindicated

Refer to allergist or other appropriate specialist

Consider administration of the implicated mRNA vaccine under medical supervision in hospital, or, where reaction was to AstraZeneca vaccine give alternative vaccine in any setting

Consider observation for 30 minutes

Written by Dr Claire Davies