Go through these in order and stop at the first one that applies. If you are reading this for someone else, answer for them.
Call emergency services if you also develop difficulty breathing, faintness, or sudden swelling of the lips, tongue, or throat.
These symptoms suggest a serious allergic reaction rather than lichenification itself.
Seek same-day medical advice if the area becomes rapidly more red or discoloured, warm, swollen, or painful, particularly if there is pus, a bad smell, fever, or you feel unwell.
These changes may indicate a skin infection.
Get urgent assessment for severe pain, widespread blistering, skin peeling, or a rapidly changing rash.
These are not typical features of simple lichenification.
Book a routine appointment if the patch persists, spreads, repeatedly returns, or affects sleep and daily activities.
You should also arrange an assessment if the skin is cracked or bleeding, the itching is severe, or self-care has not helped.
Every sign above is quoted from the sofidex article on Lichenified. If you are not sure, err upward — it is always reasonable to be checked.