Everyone gets bruises after minor injuries. Bruising is caused by the breaking of small blood vessels under the skin, resulting in bleeding in the area. It takes a day or two before the blood reaches the skin, when it can be seen as a bruise. If there’s a large bruise for instance on the leg, gravity can make the blood travel down to the foot, to an area outside the original injury.
Bruises heal on their own. Cells in the body clean away the blood in a little over a week. The bruise initially turns yellowish and then disappears. If you have nothing more than a large bruise following an injury, you do not have to visit a doctor. The other consequences of the injury determine the need for medical attention.
The tendency to bruising varies from one person to another. Some people get bruises even after injuries that are so minor that they don’t even notice them. You don’t have to worry about small bruises (less than 3 cm in diameter) even if they seem to have developed without a clear cause. NSAIDs such as acetylsalicylic acid (aspirin), ibuprofen and ketoprofen increase the tendency to bruising. If tendency to bruising is evident when using these medicines, you should stop using them if possible.
Elderly people may have bluish bruises under the skin on their forearms and on the back of their hands. These are caused by breaking of small blood vessels due to increased frailness and looseness of the skin. Even if such bruises may look bad, they are not a sign of a serious disease and don’t require an appointment with a doctor.
When should you seek treatment?
Sometimes, bruises that appear without an apparent reason may be due to a blood disorder affecting blood coagulation. Medicines affecting blood coagulation may also increase bruising.
You should see a doctor if:
- You have several bruises or one large bruise on your skin (over 3 cm in diameter) without an apparent reason.
- You have bruising during the use of a medicine affecting blood coagulation (Marevan®).
- You have bruising accompanied by general symptoms such as tiredness, weight loss and deterioration of overall condition.
Information sources: The Finnish Medical Society Duodecim: Terveysportti, Lääkärin tietokanta database
FSHS General Practitioner / 29 March 2022