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 or seek emergency care for:
Severe difficulty breathing, gasping, or ribs pulling inward with breathing
Blue, grey, or very pale lips, skin, or face
Persistent chest pain or pressure
New confusion, extreme drowsiness, collapse, or difficulty waking
A seizure
Coughing up significant amounts of blood
Severe weakness or inability to stand
A child who is not responding normally or cannot drink
Any fever in a baby younger than 12 weeks
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 advice if you may have flu and are pregnant, have a weakened immune system, have a significant long-term condition, or are in an age group at higher risk.
Early advice matters because antiviral treatment works best when started soon after symptoms begin.
These signs can have causes other than flu, but they need urgent assessment.
3
Does any of this apply?
Book an appointment
Arrange medical review if symptoms are getting worse, are not beginning to improve after about a week, or improve and then return with fever or a worse cough.
You should also seek help for signs of dehydration, such as very dark urine, much less urination, a dry mouth, or difficulty keeping fluids down.
Every sign above is quoted from the sofidex article on Flu. If you are not sure, err upward — it is always reasonable to be checked.