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
Emergency care is rarely needed for lichen planus itself.
Get urgent emergency help if you cannot swallow fluids and are becoming dehydrated, or if you develop difficulty breathing.
Widespread blistering, skin peeling, or sores affecting several body linings after starting a medicine also needs immediate assessment because this is not typical lichen planus and may indicate a more serious 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 advice if:
Mouth pain stops you eating or drinking normally
A mouth or genital ulcer lasts longer than two weeks
An affected area becomes thicker, develops a lump, bleeds, or changes appearance
Scalp pain or redness is accompanied by increasing hair loss
Genital scarring affects urination, menstruation, or sexual activity
You develop spreading redness, warmth, pus, or fever
3
Does any of this apply?
Book an appointment
Arrange a routine appointment if you develop a persistent itchy rash, white or sore areas in your mouth, genital discomfort, unexplained nail damage, or patchy hair loss.
Early assessment is especially useful for scalp, nail, or genital symptoms because some damage can become permanent.
Every sign above is quoted from the sofidex article on Lichen planus. If you are not sure, err upward — it is always reasonable to be checked.