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 for trouble breathing, faintness, or swelling of the face, mouth, or throat.
These symptoms relate to a severe reaction rather than hair loss itself.
Seek same-day medical advice for a painful or soft swollen area of scalp, pus, rapidly spreading redness, or fever.
These features can occur with a significant infection or intense inflammation.
Get urgent help after a hair product or treatment if you develop a serious chemical burn.
Book a routine appointment if your hair loss is sudden, patchy, steadily worsening, or causing concern.
You should also arrange an assessment if it affects your eyebrows or eyelashes, follows a medicine change, or comes with scalp itching, scaling, pain, or burning.
Every sign above is quoted from the sofidex article on Hair loss. If you are not sure, err upward — it is always reasonable to be checked.