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
Seek emergency help if sudden heavy sweating occurs with chest pain or pressure, severe breathing difficulty, fainting, confusion, or grey or blue skin.
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
Prompt medical assessment is appropriate if sweating:
Began suddenly without a clear reason
Started after a new medicine or dose change
Occurs with repeated fever, unexplained weight loss, or ongoing diarrhoea
Is associated with shaking, confusion, or suspected low blood sugar
Causes signs of dehydration, such as dizziness or very dark urine
Sweating in this setting may be a sign of another urgent medical problem rather than hyperhidrosis itself.
3
Does any of this apply?
Book an appointment
Arrange a routine appointment if sweating is new, persistent, affects your daily life, or regularly wakes you from sleep.
It is also worth seeking advice if over-the-counter antiperspirants have not helped or are causing significant irritation.
Every sign above is quoted from the sofidex article on Hyperhidrosis. If you are not sure, err upward — it is always reasonable to be checked.