What causes easy bruising on the legs?

A bruise forms when small blood vessels under the skin leak after an impact. Legs can collect bruises from furniture, exercise, shaving, or daily activity that you do not remember. Sun-damaged skin becomes more fragile, so minor contact may leave a visible mark; see Sun-Damaged Skin for related skin changes. Medicines such as blood thinners, some anti-inflammatory medicines, and steroid tablets can make bruising easier. Less commonly, a platelet, clotting, liver, or nutritional problem contributes. The pattern matters: note whether bruises are new, spreading, large, painful, or appearing alongside other bleeding.

Record when each bruise appeared, where it is, and any recent injury, new medicine, supplement, illness, or change in exercise. Protect the area from further knocks and use a cool pack wrapped in cloth for short periods during the first day if it is tender. Do not stop a prescribed medicine without medical advice. A clinician may examine your skin and review medicines, then decide whether blood tests are appropriate. Take photographs as bruises change so the pattern is easier to discuss.

Arrange medical assessment if bruises appear repeatedly without a clear injury, are increasing, or occur with nosebleeds, bleeding gums, unusually heavy periods, blood in urine or stool, marked tiredness, fever, or tiny red-purple spots. Seek urgent care for severe pain or swelling, a rapidly enlarging bruise, bleeding that will not stop, faintness, or a bruise after a significant injury. Sudden widespread bruising deserves prompt review, especially after a medicine change.

Ask whether your medicines or supplements can increase bruising, whether the pattern suggests a blood or skin problem, and which warning signs should prompt urgent help. Bring a complete medicine list and mention family members with unusual bleeding.