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 for sudden shortness of breath, chest pain, coughing up blood, fainting, or severe weakness.
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
Arrange prompt medical assessment for a new painful, warm, hard, or discoloured vein.
Symptoms cannot reliably distinguish a superficial clot from a DVT, skin infection, or another cause.
Seek urgent same-day care if:
Pain, redness, or hardness is spreading toward the groin or knee
Most or all of the leg or arm becomes swollen
Symptoms rapidly worsen despite treatment
You develop fever, pus, spreading redness, or feel significantly unwell
New symptoms occur while you are taking an anticoagulant
You have major bleeding, blood in vomit or urine, or black stools
These can be symptoms of a pulmonary embolism or another urgent condition.
3
Does any of this apply?
Book an appointment
Routine follow-up is appropriate when symptoms are steadily improving but the vein remains firm, mildly tender, or discoloured.
Mention persistent symptoms, repeated episodes, or medicine side effects at that review.
Every sign above is quoted from the sofidex article on Superficial thrombophlebitis. If you are not sure, err upward — it is always reasonable to be checked.