Go through these in order and stop at the first one that applies. If you are reading this for someone else, answer for them.
Get emergency help for rapidly spreading redness with severe illness, confusion, fainting, or difficulty breathing.
Seek urgent medical advice if a blister or wound becomes increasingly painful, warm, swollen, or surrounded by spreading redness.
Pus, red streaks, or fever can indicate infection.
Severe abdominal pain, new weakness, seizures, or major changes in awareness also need urgent assessment.
These are not typical skin symptoms of PCT and should not be assumed to be part of it.
Arrange a routine medical appointment if you develop repeated blisters on the backs of your hands, unusually fragile sun-exposed skin, or unexplained dark urine.
These symptoms have several possible causes and require appropriate testing.
Follow-up is also important if planned blood tests or treatment sessions have been missed.
The article also says
If you have already been diagnosed, contact your usual clinical team if new blisters return, wounds are not healing, or you notice medication side effects.
Every sign above is quoted from the sofidex article on Symptomatic porphyria. If you are not sure, err upward — it is always reasonable to be checked.