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 for trouble breathing, wheezing, faintness, confusion, or swelling of the tongue or throat.
These can be signs of anaphylaxis, a severe immediate allergic reaction.
They are not typical features of lichen urticatus.
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 the skin becomes increasingly painful, hot, swollen, or red, or if there is pus, spreading redness, fever, or yellow crusting.
These changes may indicate infection rather than the usual bite reaction.
Get urgent assessment for a widespread blistering rash, sores involving the eyes or mouth, or a rash accompanied by significant illness.
3
Does any of this apply?
Book an appointment
Arrange a routine appointment if:
Itchy bumps keep returning or the cause is unclear
Symptoms are affecting sleep or daily activities
Several household members have persistent nighttime itching
The rash does not improve after the suspected bite source is controlled
You need advice about safe treatment for a child or during pregnancy
Every sign above is quoted from the sofidex article on Lichen urticatus. If you are not sure, err upward — it is always reasonable to be checked.