Go through these in order and stop at the first one that applies. If you are reading this for someone else, answer for them.
1
Is any of this happening now?
Call 911
Call emergency services during or soon after a blood transfusion if you develop:
Difficulty breathing or wheezing
Swelling of the lips, tongue, face, or throat
Widespread hives with dizziness or faintness
Sudden collapse or severe weakness
These can be signs of anaphylaxis, a severe allergic reaction.
Other emergency signs, for anyone
Someone who is struggling to breathe, gasping, choking, or cannot get words out
Someone who has chest pain, tightness or pressure lasting more than a few minutes
Someone who has sudden weakness or drooping on one side of the face or body, slurred speech, or sudden confusion
Someone who is unconscious, or cannot be woken
Someone who is bleeding heavily and it will not stop with firm pressure
Someone who has had a seizure that will not stop, or does not wake up afterwards
Someone who has lips or skin that look pale, blue, grey or blotchy
Someone who you believe has taken an overdose or swallowed something poisonous
2
Is any of this happening?
Be seen today
Seek prompt medical assessment for a high fever with worsening illness, shortness of breath, chest pain, dehydration, coughing up blood, or a severe infection that is not improving as expected.
Transfusion staff should also be told immediately about chills, fever, back pain, chest discomfort, or any sudden change in how you feel.
3
Does any of this apply?
Book an appointment
Arrange a routine appointment if you have repeated sinus, ear, or chest infections; diarrhoea that persists or returns; unexplained weight loss; or symptoms suggesting an allergy or autoimmune condition.
Follow-up is also appropriate if infections are becoming more frequent or taking longer to clear.
Every sign above is quoted from the sofidex article on Selective deficiency of IgA. If you are not sure, err upward — it is always reasonable to be checked.