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 care if you have possible signs of sepsis or a rapidly progressing deep infection, including:
Confusion, fainting, severe drowsiness, or difficulty waking
Trouble breathing or very rapid breathing
Cold, clammy, mottled, or unusually pale skin
Severe weakness or a feeling that something is seriously wrong
Rapidly spreading swelling, severe pain, blisters, or dusky skin
Signs of a severe allergic reaction after medicine, such as facial swelling or breathing difficulty
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 same-day medical advice if you develop a tender red or dark streak extending from a wound, especially if it is spreading or you also have fever, chills, swollen lymph nodes, or increasing pain.
Prompt assessment is also important if you have diabetes, lymphoedema, poor circulation, or weakened immune defences.
3
Does any of this apply?
Book an appointment
Arrange routine follow-up if symptoms are not beginning to improve after the timeframe given by the treating healthcare professional, if they worsen at any point, or if lymphangitis keeps returning.
New diarrhoea, rash, vomiting, or other possible antibiotic side effects should also be reported.
Every sign above is quoted from the sofidex article on Lymphangitis. If you are not sure, err upward — it is always reasonable to be checked.