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
Call emergency services if you develop:
New or rapidly worsening difficulty breathing
Difficulty speaking because you cannot get enough breath
Inability to swallow saliva or repeated choking
Severe weakness that is worsening quickly
Bluish or grey lips, confusion, or unusual drowsiness
A fingertip oxygen reading can remain normal until late in respiratory muscle weakness, so a normal reading should not delay emergency help.
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 for new swallowing problems, a weak cough, shortness of breath when lying down, fever or infection with increasing weakness, or a clear decline in your usual strength.
3
Does any of this apply?
Book an appointment
Arrange routine follow-up if symptoms are gradually becoming harder to control, side effects are troubling you, or weakness regularly returns before the next dose of symptom medicine.
Medication changes should be made with the prescribing team.
The article also says
Do not drive yourself if breathing or swallowing is seriously affected.
Every sign above is quoted from the sofidex article on Myasthenia gravis. If you are not sure, err upward — it is always reasonable to be checked.