How much bruising is normal?
More than most people assume. Occasional bruises on shins, knees, thighs, forearms and hips — the parts of the body that meet door frames, table corners and dishwasher doors — are entirely ordinary, and not remembering the knock is normal too, particularly if you are busy or active.
What is worth explaining: a clear change from your own normal, bruises appearing without any trauma at all, bruises in unusual places, very large or lumpy bruises, or bruising together with any other kind of bleeding.
Does it matter where they are?
Considerably. Shins and forearms are exposed and get knocked constantly. The back, chest, abdomen, buttocks and face are not — so bruising there is less easily explained by ordinary daily life and deserves a proper look, both medically and otherwise.
Could it be my blood thinner?
Almost certainly a contributor if you take one. Aspirin, clopidogrel, warfarin and the DOACs all cause easier bruising by design — that is the intended effect working on small vessels rather than a sign of anything going wrong.
Do not stop taking it. The risk being prevented — stroke, heart attack, or a clot — is far greater than bruising. What is worth doing is checking whether you also take something that adds to the effect: ibuprofen, an SSRI, or fish oil, all of which stack on top.
Could this be leukaemia?
It is the fear that brings people here, and it deserves a direct answer. Easy bruising alone, in someone who is otherwise well, is very rarely leukaemia. What raises real concern is bruising plus other things: marked fatigue, recurrent or unusual infections, unexplained fevers, drenching night sweats, weight loss, bone pain, bleeding gums, or petechiae.
A full blood count is a cheap, fast, and highly informative test — a normal one is genuinely reassuring, and it is the right way to answer this question rather than living with it.
What are petechiae, and why do they matter more than bruises?
Tiny flat red, purple or brown pinpoint spots, often clustered on the lower legs, that do not fade when pressed with a glass. They are not bruises — they indicate very low platelets or a problem with small blood vessels, and they warrant a blood count promptly.
The distinguishing features are that they are flat rather than raised, tiny rather than patchy, and do not blanch.
Would vitamin C or vitamin K help?
Only if you are actually deficient, which is uncommon. Severe vitamin C deficiency does cause bruising and bleeding gums, but it is rare outside of very restricted diets and heavy alcohol use. Vitamin K deficiency causes bleeding but is unusual in adults eating normally. Supplements marketed for bruising are unlikely to help, and vitamin K in particular interferes with warfarin — do not start it without advice.
Could it be my liver, or alcohol?
Yes, and this is one of the more common serious causes. The liver makes most of the proteins that clot blood, so liver disease produces easy bruising, and alcohol contributes both through the liver and by suppressing platelets directly. Other clues would be abdominal swelling, yellowing of the skin or eyes, spider-like vessels on the chest, and swollen ankles. Liver function tests and a blood count answer it.
What tests would you arrange?
Full blood count — which checks platelets and looks for anything abnormal in the white cells — clotting studies, liver function, kidney function and ferritin, with thyroid function where relevant.
That set answers the question for the great majority of people, usually reassuringly, and it can be arranged the same week. Where it is abnormal, we refer to haematology.