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 symptoms of severe blood loss, such as fainting, confusion, marked weakness, difficulty breathing, or cold and clammy skin.
Emergency care is also needed for serious head-injury symptoms or signs of compartment syndrome.
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
Contact a healthcare professional promptly for a large new bruise while taking an anticoagulant, particularly if there is ongoing swelling or other bleeding.
Follow the care plan given by the anticoagulant prescriber.
Seek urgent same-day assessment for new widespread bruising or petechiae, especially with fever or feeling unwell.
Blood in urine, red or black stools, vomiting blood, or bleeding that does not stop also needs urgent care.
3
Does any of this apply?
Book an appointment
Arrange routine medical follow-up if bruises:
Appear often without a remembered injury
Are becoming larger, more numerous, or more painful
Develop after starting a medicine or supplement
Do not show gradual improvement
Occur with frequent nosebleeds, gum bleeding, heavy periods, or prolonged bleeding from small cuts
Are accompanied by unusual tiredness, weight loss, or recurrent fever
Interfere with walking, work, sleep, or joint movement
The article also says
A small bruise that steadily becomes less painful and begins to fade can usually be watched at home.
Depending on its size and location, complete fading may take several weeks.
Every sign above is quoted from the sofidex article on Bruise. If you are not sure, err upward — it is always reasonable to be checked.